#ifndef EPHYSICS_H
#define EPHYSICS_H

/**
 * @page ephysics_main EPhysics
 *
 * @date 2012 (created)
 *
 * @section toc Table of Contents
 *
 * @li @ref ephysics_main_intro
 * @li @ref ephysics_main_compiling
 * @li @ref ephysics_main_next_steps
 * @li @ref ephysics_main_intro_example
 *
 * @section ephysics_main_intro Introduction
 *
 * EPhysics is a library that makes it easy to use Ecore, Evas and Bullet
 * Physics together. It's a kind of wrapper, a glue, between these libraries.
 * It's not intended to be a physics library (we already have many out there).
 *
 * @image html diagram_ephysics.png
 * @image latex diagram_ephysics.eps
 *
 * @section ephysics_main_compiling How to compile
 *
 * Ephysics is a library your application links to. The procedure for this is
 * very simple. You simply have to compile your application with the
 * appropriate compiler flags that the @c pkg-config script outputs. For
 * example:
 *
 * Compiling C or C++ files into object files:
 *
 * @verbatim
   gcc -c -o main.o main.c `pkg-config --cflags ephysics`
   @endverbatim
 *
 * Linking object files into a binary executable:
 *
 * @verbatim
   gcc -o my_application main.o `pkg-config --libs ephysics`
   @endverbatim
 *
 * See @ref pkgconfig
 *
 * @section ephysics_main_next_steps Next Steps
 *
 * After you understood what EPhysics is and installed it in your system
 * you should proceed understanding the programming interface.
 *
 * Recommended reading:
 * @li @ref EPhysics
 * @li @ref EPhysics_World
 * @li @ref EPhysics_Body
 * @li @ref EPhysics_Camera
 * @li @ref EPhysics_Constraint
 * @li @ref EPhysics_Quaternion
 * @li @ref EPhysics_Shape
 *
 * @section ephysics_main_intro_example Introductory Example
 *
 * @include test_bouncing_ball.c
 *
 * More examples can be found at @ref ephysics_examples.
 */

#include <Evas.h>
#include <Efl_Config.h>

#ifdef EAPI
# undef EAPI
#endif

#ifdef _WIN32
# ifdef EFL_BUILD
#  ifdef DLL_EXPORT
#   define EAPI __declspec(dllexport)
#  else
#   define EAPI
#  endif
# else
#  define EAPI __declspec(dllimport)
# endif
#else
# ifdef __GNUC__
#  if __GNUC__ >= 4
#   define EAPI __attribute__ ((visibility("default")))
#  else
#   define EAPI
#  endif
# else
#  define EAPI
# endif
#endif

#ifdef __cplusplus
extern "C" {
#endif

#define EPHYSICS_VERSION_MAJOR EFL_VERSION_MAJOR
#define EPHYSICS_VERSION_MINOR EFL_VERSION_MINOR

/**
 * @file
 * @brief These routines are used for EPhysics library interaction.
 */

/**
 * @brief Physics simulation integration and visual effects.
 * @defgroup EPhysics EPhysics
 *
 * @{
 *
 */

/**
 * Initialize EPhysics
 *
 * Initializes Bullet physics engine.
 *
 * @return The init counter value.
 *
 * @see ephysics_shutdown().
 *
 * @ingroup EPhysics
 */
EAPI int ephysics_init(void);

/**
 * Shutdown EPhysics
 *
 * Shutdown Bullet physics engine. If init count reaches 0, all the existing
 * worlds will be deleted, and consequently all the bodies.
 *
 * @return EPhysics' init counter value.
 *
 * @see ephysics_init().
 *
 * @ingroup EPhysics
 */
EAPI int ephysics_shutdown(void);

/**
 * @}
 */

/**
 * @defgroup EPhysics_Quaternion EPhysics Quaternion
 * @ingroup EPhysics
 *
 * @{
 *
 * Quaternions are used to perform linear algebra rotations.
 *
 * Functions regarding rotation, like @ref ephysics_body_rotation_set()
 * and @ref ephysics_body_rotation_get() would need that. Quaternions
 * can be used to rotate evas maps as well, with evas_map_util_quat_rotate(),
 * but in this case quaternion values need to be get with
 * @ref ephysics_quaternion_get(), since evas don't accept
 * EPhysics_Quaternion type.
 *
 * A quaternion can be created with ephysics_quaternion_new(), and many
 * operations can be performed with that, as:
 * @li Sum: @ref ephysics_quaternion_sum()
 * @li Difference: @ref ephysics_quaternion_diff()
 * @li Multiple by another quaternion: @ref ephysics_quaternion_multiply()
 * @li Multiply by scalar: @ref ephysics_quaternion_scale()
 * @li Divide by scalar: @ref ephysics_quaternion_inverse_scale()
 * @li Calculate length: @ref ephysics_quaternion_length_get()
 * @li Calculate angle between quaternions: @ref ephysics_quaternion_angle_get()
 */

/**
 * @typedef EPhysics_Quaternion
 *
 * Quaternion handle, represents a quaternion to be used to rotate bodies.
 *
 * Created with @ref ephysics_quaternion_new() and deleted with free().
 *
 * @ingroup EPhysics_Quaternion
 */
typedef struct _EPhysics_Quaternion EPhysics_Quaternion;

/**
 * @struct _EPhysics_Quaternion
 *
 * Quaternion coordinates and rotation (w, x, y, z)
 */
struct _EPhysics_Quaternion
{
   double w; /**< rotation */
   double x; /**< x coordinate */
   double y; /**< y coordinate */
   double z; /**< z coordinate */
};

/**
 * @brief
 * Create a new quaternion.
 *
 * By default a quaternion is created as identity  (w = 1, x = 0, y = 0, z = 0).
 * This values can be modified later by quaternion operations or set directly.
 *
 * @return The created quaternion or @c NULL on error.
 *
 * @note It should be deleted with free() after usage is concluded.
 *
 * @see ephysics_quaternion_set();
 * @see ephysics_quaternion_axis_angle_set();
 * @see ephysics_quaternion_euler_set();
 * @see ephysics_quaternion_scale();
 * @see ephysics_quaternion_sum();
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI EPhysics_Quaternion *ephysics_quaternion_new(void);

/**
 * @brief
 * Get quaternion values.
 *
 * @param quat Quaternion to get values from.
 * @param x The x coordinate.
 * @param y The y coordinate.
 * @param z The z coordinate.
 * @param w The rotation.
 *
 * @see ephysics_quaternion_set();
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI void ephysics_quaternion_get(const EPhysics_Quaternion *quat, double *x, double *y, double *z, double *w);

/**
 * @brief
 * Get quaternion axis and angle.
 *
 * @param quat Quaternion to get values from.
 * @param nx The x component of the axis of rotation.
 * @param ny The y component of the axis of rotation.
 * @param nz The z component of the axis of rotation.
 * @param a The angle of rotation.
 *
 * @see ephysics_quaternion_axis_angle_set();
 * @see ephysics_quaternion_get();
 * @see ephysics_quaternion_set();
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI void ephysics_quaternion_axis_angle_get(const EPhysics_Quaternion *quat, double *nx, double *ny, double *nz, double *a);

/**
 * @brief
 * Set quaternion values.
 *
 * @param quat Quaternion to be set.
 * @param x The x coordinate.
 * @param y The y coordinate.
 * @param z The z coordinate.
 * @param w The rotation.
 *
 * @see ephysics_quaternion_get();
 * @see ephysics_quaternion_euler_set();
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI void ephysics_quaternion_set(EPhysics_Quaternion *quat, double x, double y, double z, double w);

/**
 * @brief
 * Set quaternion using axis angle notation.
 *
 * [w, x, y, z] = [cos(a/2), sin(a/2) * nx, sin(a/2)* ny, sin(a/2) * nz]
 *
 * @param quat Quaternion to be set.
 * @param nx The x component of the axis of rotation.
 * @param ny The y component of the axis of rotation.
 * @param nz The z component of the axis of rotation.
 * @param a The angle of rotation.
 *
 * @see ephysics_quaternion_axis_angle_get();
 * @see ephysics_quaternion_set();
 * @see ephysics_quaternion_euler_set();
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI void ephysics_quaternion_axis_angle_set(EPhysics_Quaternion *quat, double nx, double ny, double nz, double a);

/**
 * @brief
 * Set quaternion using Euler angles.
 *
 * It's an alternative to @ref ephysics_quaternion_set() usage. Euler angles
 * will be converted.
 *
 * @param quat Quaternion to be set.
 * @param yaw The angle around Y axis.
 * @param pitch The angle around X axis.
 * @param roll The angle around Z axis.
 *
 * @see ephysics_quaternion_get();
 * @see ephysics_quaternion_set();
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI void ephysics_quaternion_euler_set(EPhysics_Quaternion *quat, double yaw, double pitch, double roll);

/**
 * @brief
 * Normalize the quaternion.
 *
 * A normalized quaternion is such that x^2 + y^2 + z^2 + w^2 = 1.
 *
 * @param quat Quaternion to be normalized.
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI void ephysics_quaternion_normalize(EPhysics_Quaternion *quat);

/**
 * @brief
 * Invert the quaternion.
 *
 * @param quat Quaternion to be inverted.
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI void ephysics_quaternion_invert(EPhysics_Quaternion *quat);

/**
 * @brief
 * Scale the quaternion.
 *
 * @param quat Quaternion to be scaled.
 * @param scale The scale factor.
 *
 * @see ephysics_quaternion_inverse_scale()
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI void ephysics_quaternion_scale(EPhysics_Quaternion *quat, double scale);

/**
 * @brief
 * Inversely scale the quaternion.
 *
 * @param quat Quaternion to be scaled.
 * @param scale The scale factor.
 *
 * @see ephysics_quaternion_scale()
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI void ephysics_quaternion_inverse_scale(EPhysics_Quaternion *quat, double scale);

/**
 * @brief
 * Returns a sum of two quaternions.
 *
 * @param quat1 First quaternion to sum.
 * @param quat2 Second quaternion to sum.
 * @param result Quaternion used to store the result. If it's @c NULL, a new
 * quaternion will be allocated (and should be freed after usage).
 * @return The sum quaternion or @c NULL on error.
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI EPhysics_Quaternion *ephysics_quaternion_sum(const EPhysics_Quaternion *quat1, const EPhysics_Quaternion *quat2, EPhysics_Quaternion *result);

/**
 * @brief
 * Returns a difference between two quaternions.
 *
 * @param quat1 First quaternion.
 * @param quat2 Second quaternion.
 * @param result Quaternion used to store the result. If it's @c NULL, a new
 * quaternion will be allocated (and should be freed after usage).
 * @return The difference between @p quat1 and @p quat2, or @c NULL on error.
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI EPhysics_Quaternion *ephysics_quaternion_diff(const EPhysics_Quaternion *quat1, const EPhysics_Quaternion *quat2, EPhysics_Quaternion *result);

/**
 * @brief
 * Multiply two quaternions.
 *
 * @param quat1 First quaternion.
 * @param quat2 Second quaternion.
 * @param result Quaternion used to store the result. If it's @c NULL, a new
 * quaternion will be allocated (and should be freed after usage).
 * @return The @p quat1 multiplied by @p quat2 on the right, or @c NULL
 * on error.
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI EPhysics_Quaternion *ephysics_quaternion_multiply(const EPhysics_Quaternion *quat1, const EPhysics_Quaternion *quat2, EPhysics_Quaternion *result);

/**
 * @brief
 * Return the quaternion which is the result of Spherical Linear Interpolation
 * between two quaternions.
 *
 * Slerp interpolates assuming constant velocity.
 *
 * @param quat1 First quaternion.
 * @param quat2 Second quaternion.
 * @param ratio The ratio between @p quat1 and @p quat2 to interpolate. If
 * @p ratio = 0, the result is @p quat1, if @p ratio = 1, the result is
 * @p quat2.
 * @param result Quaternion used to store the result. If it's @c NULL, a new
 * quaternion will be allocated (and should be freed after usage).
 * @return The result of slerp between @p quat1 and @p quat2, or @c NULL
 * on error.
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI EPhysics_Quaternion *ephysics_quaternion_slerp(const EPhysics_Quaternion *quat1, const EPhysics_Quaternion *quat2, double ratio, EPhysics_Quaternion *result);

/**
 * @brief
 * Return the dot product between two quaternions.
 *
 * @param quat1 First quaternion.
 * @param quat2 Second quaternion.
 * @return The dot product between @p quat1 and @p quat2 or @c 0 on error.
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI double ephysics_quaternion_dot(const EPhysics_Quaternion *quat1, const EPhysics_Quaternion *quat2);

/**
 * @brief
 * Return the angle between two quaternions.
 *
 * @param quat1 First quaternion.
 * @param quat2 Second quaternion.
 * @return The angle between @p quat1 and @p quat2 or @c 0 on error.
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI double ephysics_quaternion_angle_get(const EPhysics_Quaternion *quat1, const EPhysics_Quaternion *quat2);

/**
 * @brief
 * Return the length of the quaternion.
 *
 * @param quat Quaternion to get length of.
 * @return The length of @p quat or @c 0 on error.
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI double ephysics_quaternion_length_get(const EPhysics_Quaternion *quat);

/**
 * @brief
 * Return the length squared of the quaternion.
 *
 * @param quat Quaternion to get length of.
 * @return The length of @p quat or @c 0 on error.
 *
 * @ingroup EPhysics_Quaternion
 */
EAPI double ephysics_quaternion_length2_get(const EPhysics_Quaternion *quat);

/**
 * @}
 */

/**
 * @defgroup EPhysics_Shape EPhysics Shape
 * @ingroup EPhysics
 *
 * @{
 *
 * Shapes are used to create bodies with shapes that differ from primitive
 * ones, like box and cylinder.
 *
 * A shape consists in a group of points, the vertices of the body to be
 * created later with @ref ephysics_body_shape_add().
 *
 * A new shape is created with @ref ephysics_shape_new() and points are
 * set with @ref ephysics_shape_point_add(). A shape can be used to
 * create many bodies. When done, it's required to delete the shape
 * with @ref ephysics_shape_del().
 *
 * A shape can be loaded from a file describing it with
 * @ref ephysics_shape_load(), and can be saved to a file with
 * @ref ephysics_shape_save(). With that shapes can be done or visualized
 * on design applications.
 *
 * @note Using primitive shapes has better performance than generic shapes.
 * @note For now, only convex shapes are supported.
 *
 */

/**
 * @typedef EPhysics_Shape
 *
 * Shape handle, represents a shape to be used to create a body.
 *
 * Created with @ref ephysics_shape_new() and deleted with
 * @ref ephysics_shape_del().
 *
 * @ingroup EPhysics_Shape
 */
typedef struct _EPhysics_Shape EPhysics_Shape;

/**
 * @brief
 * Create a new shape.
 *
 * The returned shape initially doesn't has points set, so it's required
 * to set vertices with @ref ephysics_shape_point_add().
 *
 * After the shape is completely defined, all the points were added,
 * it's possible to create one or more bodies with
 * @ref ephysics_body_shape_add().
 *
 * @return The created shape or @c NULL on error.
 *
 * @see ephysics_shape_del().
 * @see ephysics_shape_load().
 *
 * @ingroup EPhysics_Shape
 */
EAPI EPhysics_Shape *ephysics_shape_new(void);

/**
 * @brief
 * Delete a shape.
 *
 * After a shape is used to create the wanted bodies, it's required
 * to delete it. It won't be deleted automatically by ephysics
 * at any point, even on shutdown. The creator is responsible to
 * free it after usage is concluded.
 *
 * @param shape The shape to be deleted.
 *
 * @see ephysics_shape_new().
 *
 * @ingroup EPhysics_Shape
 */
EAPI void ephysics_shape_del(EPhysics_Shape *shape);

/**
 * @brief
 * Add a new point to the shape.
 *
 * Any point can be added to a shape, but only vertices matter.
 * A vertex is a special kind of point that describes a corner of
 * geometric shapes. The final shape will be constructed in such a way
 * it will have all the added points and will be convex.
 *
 * The center of mass will be the centroid, or geometric center of the
 * shape.
 *
 * The order of points doesn't matter.
 *
 * For example, to create a pentagon:
 *
 * @code
 * EPhysics_Shape *shape = ephysics_shape_new();
 *
 * ephysics_shape_point_add(shape, 0, 24, -10);
 * ephysics_shape_point_add(shape, 0, 24, 10);
 * ephysics_shape_point_add(shape, 35, 0, -10);
 * ephysics_shape_point_add(shape, 35, 0, 10);
 * ephysics_shape_point_add(shape, 70, 24, -10);
 * ephysics_shape_point_add(shape, 70, 24, 10);
 * ephysics_shape_point_add(shape, 56, 66, -10);
 * ephysics_shape_point_add(shape, 56, 66, 10);
 * ephysics_shape_point_add(shape, 14, 66, -10);
 * ephysics_shape_point_add(shape, 14, 66, 10);
 *
 * ephysics_body_shape_add(world, shape);
 *
 * ephysics_shape_del(shape);
 * @endcode
 *
 * @param shape The shape to be modified.
 * @param x Point position at x axis.
 * @param y Point position at y axis.
 * @param z Point position at z axis.
 * @return @c EINA_TRUE on success or EINA_FALSE on error.
 *
 * @see ephysics_shape_new().
 *
 * @ingroup EPhysics_Shape
 */
EAPI Eina_Bool ephysics_shape_point_add(EPhysics_Shape *shape, double x, double y, double z);

/**
 * @brief
 * Load the shape from a file.
 *
 * Useful to edit shapes on design tools and load it from an exported file.
 *
 * Also it helps to avoid lots of @ref ephysics_shape_point_add() in
 * the code, and keep a better separation between code logic and
 * design stuff.
 *
 * @param filename The path to the file describing the shape.
 * @return The loaded shape or @c NULL on error.
 *
 * @note Not implemented yet.
 *
 * @see ephysics_shape_new() for more details.
 * @see ephysics_shape_save().
 *
 * @ingroup EPhysics_Shape
 */
EAPI EPhysics_Shape *ephysics_shape_load(const char *filename);

/**
 * @brief
 * Save the shape to a file.
 *
 * It can be useful to visualize it on design tools.
 *
 * @param shape The shape to be saved.
 * @param filename The path to save the shape.
 * @return @c EINA_TRUE on success or EINA_FALSE on error.
 *
 * @note Not implemented yet.
 *
 * @see ephysics_shape_new().
 * @see ephysics_shape_load().
 *
 * @ingroup EPhysics_Shape
 */
EAPI Eina_Bool ephysics_shape_save(const EPhysics_Shape *shape, const char *filename);

/**
 * @}
 */


/**
 * @typedef EPhysics_Body
 *
 * Body handle, represents an object on EPhysics world.
 *
 * Many types of bodies can be created:
 * @li @ref ephysics_body_cylinder_add()
 * @li @ref ephysics_body_box_add()
 * @li @ref ephysics_body_shape_add()
 * @li @ref ephysics_body_soft_cylinder_add()
 * @li @ref ephysics_body_soft_box_add()
 *
 * and it can be deleted with @ref ephysics_body_del().
 *
 * @ingroup EPhysics_Body
 */
typedef struct _EPhysics_Body EPhysics_Body;

/**
 * @defgroup EPhysics_Camera EPhysics Camera
 * @ingroup EPhysics
 *
 * @{
 *
 * A camera defines the region of the physics world that will be rendered
 * on the canvas. It sets the point of view.
 *
 * Every world has a camera, that can be gotten with
 * @ref ephysics_world_camera_get().
 * Its position can be set with @ref ephysics_camera_position_set() or
 * can be set to track a body, with @ref ephysics_camera_body_track();
 *
 */

typedef struct _EPhysics_Camera EPhysics_Camera; /**< Camera handle, used to change the position of the frame to be rendered. Every world have a camera that can be gotten with @ref ephysics_world_camera_get(). */

/**
 * @brief
 * Set camera's position.
 *
 * Camera's position referes to the position of the top-left point of the
 * camera.
 *
 * By default a camera is created to map the first quadrant of physics
 * world from the point (0, 0) to
 * (render area width / world rate, render area height / world rate).
 *
 * When render area is set with @ref ephysics_world_render_geometry_set(),
 * the camera geometry is updated to match it. So, for most cases, camera
 * won't need to be handled by the user.
 *
 * But it can be modified passing another top-left point position, so another
 * region of the physics world will be rendered on the render area.
 * So if you have a scene larger than the render area, camera handling can
 * be very useful.
 *
 * This function will make camera stop tracking a body set with
 * @ref ephysics_camera_body_track().
 *
 * @note This change will be noticed on the next physics tick, so evas objects
 * will be updated taking the camera's new position in account.
 *
 * @param camera The camera to be positioned.
 * @param x The new position on x axis, in pixels.
 * @param y The new position on y axis, in pixels.
 *
 * @see ephysics_camera_position_get().
 * @see ephysics_world_camera_get().
 * @see ephysics_world_rate_get().
 *
 * @ingroup EPhysics_Camera
 */
EAPI void ephysics_camera_position_set(EPhysics_Camera *camera, Evas_Coord x, Evas_Coord y);

/**
 * @brief
 * Get camera's position.
 *
 * @param camera The world's camera.
 * @param x Position on x axis, in pixels.
 * @param y Position on y axis, in pixels.
 *
 * @see ephysics_camera_position_set() for more details.
 *
 * @ingroup EPhysics_Camera
 */
EAPI void ephysics_camera_position_get(const EPhysics_Camera *camera, Evas_Coord *x, Evas_Coord *y);

/**
 * @brief
 * Set camera to track a body.
 *
 * When a body is tracked, the camera will move automatically, following
 * this body. It will keeps the body centralized on rendered area.
 * If it will be centralized horizontally and / or vertically depends
 * if parameters @p horizontal and @p vertical are set to @c EINA_TRUE.
 *
 * Default updates (@ref ephysics_body_evas_object_update())
 * will take care of updating evas objects associated
 * to the bodies correctly. But if you need to do it yourself, you'll need
 * to take camera's position in consideration, using
 * @ref ephysics_camera_position_get().
 *
 * @note This change will be noticed on the next physics tick, so evas objects
 * will be updated taking the camera's new position in account.
 *
 * @param camera The world's camera.
 * @param body The body tracked by the @p camera, or @c NULL if camera isn't
 * tracking any body.
 * @param horizontal @c EINA_TRUE if @p body is tracked on x axis,
 * @c EINA_FALSE otherwise;
 * @param vertical @c EINA_TRUE if @p body is tracked on y axis,
 * @c EINA_FALSE otherwise;
 *
 * @see ephysics_camera_tracked_body_get().
 * @see ephysics_camera_position_set().
 * @see ephysics_world_camera_get().
 *
 * @ingroup EPhysics_Camera
 */
EAPI void ephysics_camera_body_track(EPhysics_Camera *camera, EPhysics_Body *body, Eina_Bool horizontal, Eina_Bool vertical);

/**
 * @brief
 * Get body tracked by camera.
 *
 * @param camera The world's camera.
 * @param body The body tracked by the @p camera, or @c NULL if camera isn't
 * tracking any body.
 * @param horizontal @c EINA_TRUE if @p body is tracked on x axis,
 * @c EINA_FALSE otherwise;
 * @param vertical @c EINA_TRUE if @p body is tracked on y axis,
 * @c EINA_FALSE otherwise;
 *
 * @see ephysics_camera_body_track() for more details.
 *
 * @ingroup EPhysics_Camera
 */
EAPI void ephysics_camera_tracked_body_get(EPhysics_Camera *camera, EPhysics_Body **body, Eina_Bool *horizontal, Eina_Bool *vertical);

/**
 * @brief
 * Set perspective to be applied on the scene.
 *
 * This applies a given perspective (3D) to the world rendering.
 * It will be used when the scene is rendered, after each simulation step,
 * by @ref ephysics_body_evas_object_update().
 *
 * The @p px and @p py points specify the "infinite distance" point in the 3D
 * conversion (where all lines converge to like when artists draw 3D by hand).
 * The @p z0 value specifies the z value at which there is a 1:1 mapping between
 * spatial coordinates and screen coordinates. Any points on this z value will
 * not have their X and Y values modified in the transform.
 * Those further away (Z value higher) will shrink into the distance, and those
 * less than this value will expand and become bigger. The foc value determines
 * the "focal length" of the camera. This is in reality the distance between
 * the camera lens plane itself (at or closer than this rendering results are
 * undefined) and the @p z0 z value. This allows for some "depth" control and
 * @p foc must be greater than 0.
 *
 * Considering the world geometry, by default, perspective is set to
 * px = x + w / 2, py = y + h / 2, z0 = z + d / 2 and foc = 10 * (z + d).
 * This means the conversion point is centered on render area, and @p z0
 * is on the center of render area z axis. It is set when
 * @ref ephysics_world_render_geometry_set() is called.
 *
 * @note The unit used for all parameters is Evas coordinates.
 *
 * @note To be used, perspective need to be enabled with
 * @ref ephysics_camera_perspective_enabled_set().
 *
 * @param camera The world's camera.
 * @param px The perspective distance X coordinate
 * @param py The perspective distance Y coordinate
 * @param z0 The "0" z plane value
 * @param foc The focal distance
 *
 * @see ephysics_camera_perspective_get().
 * @see ephysics_camera_perspective_enabled_set().
 *
 * @ingroup EPhysics_Camera
 */
EAPI void ephysics_camera_perspective_set(EPhysics_Camera *camera, Evas_Coord px, Evas_Coord py, Evas_Coord z0, Evas_Coord foc);

/**
 * @brief
 * Get perspective applied on the scene.
 *
 * @param camera The world's camera.
 * @param px The perspective distance X coordinate
 * @param py The perspective distance Y coordinate
 * @param z0 The "0" z plane value
 * @param foc The focal distance
 *
 * @see ephysics_camera_perspective_set() for more details.
 * @see ephysics_camera_perspective_enabled_get().
 *
 * @ingroup EPhysics_Camera
 */
EAPI void ephysics_camera_perspective_get(const EPhysics_Camera *camera, Evas_Coord *px, Evas_Coord *py, Evas_Coord *z0, Evas_Coord *foc);

/**
 * @brief
 * Set if perspective should be applied.
 *
 * The applied perspective can be set with
 * @ref ephysics_camera_perspective_set().
 *
 * @param camera The world's camera.
 * @param enabled @c EINA_TRUE if perspective should be used, or @c EINA_FALSE
 * if it shouldn't.
 *
 * @see ephysics_camera_perspective_set() for more details.
 * @see ephysics_camera_perspective_enabled_get().
 *
 * @ingroup EPhysics_Camera
 */
EAPI void ephysics_camera_perspective_enabled_set(EPhysics_Camera *camera, Eina_Bool enabled);

/**
 * @brief
 * Return if perspective is enabled or not.
 *
 * @param camera The world's camera.
 * @return @c EINA_TRUE if perspective is enabled, or @c EINA_FALSE if it
 * isn't, or on error.
 *
 * @see ephysics_camera_perspective_set() for more details.
 * @see ephysics_camera_perspective_enabled_set().
 *
 * @ingroup EPhysics_Camera
 */
EAPI Eina_Bool ephysics_camera_perspective_enabled_get(const EPhysics_Camera *camera);

/**
 * @}
 */

/**
 * @defgroup EPhysics_World EPhysics World
 * @ingroup EPhysics
 *
 * @{
 *
 * A world is required to simulate physics between bodies.
 * It will setup collision configuration,
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Collision_
 * Detection_and_Physics_FAQ#How_do_most_physics_engines_solve_constraints.3F">
 * constraint solver</a></b>,
 * the
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Broadphase">
 * broadphase</a></b>
 * interface and a dispatcher to dispatch calculations
 * for overlapping pairs.
 *
 * A new world can be created with @ref ephysics_world_new() and deleted with
 * @ref ephysics_world_del(). It can have its gravity changed with
 * @ref ephysics_world_gravity_set() and play / paused with
 * @ref ephysics_world_running_set(). When running, the simulation will be
 * gradually stepped.
 */

typedef struct _EPhysics_World EPhysics_World; /**< World handle, most basic type of EPhysics. Created with @ref ephysics_world_new() and deleted with @ref ephysics_world_del(). */

/**
 * @enum _EPhysics_Callback_World_Type
 * @typedef EPhysics_Callback_World_Type
 *
 * Identifier of callbacks to be set for EPhysics worlds.
 *
 * @see ephysics_world_event_callback_add()
 * @see ephysics_world_event_callback_del()
 * @see ephysics_world_event_callback_del_full()
 *
 * @ingroup EPhysics_World
 */
typedef enum _EPhysics_Callback_World_Type
{
   EPHYSICS_CALLBACK_WORLD_DEL, /**< World being deleted (called before free) */
   EPHYSICS_CALLBACK_WORLD_STOPPED, /**< no objects are moving any more */
   EPHYSICS_CALLBACK_WORLD_CAMERA_MOVED, /**< camera position changed */
   EPHYSICS_CALLBACK_WORLD_UPDATE, /**< world being updated */
   EPHYSICS_CALLBACK_WORLD_LAST, /**< kept as sentinel, not really an event */
} EPhysics_Callback_World_Type;

/**
 * @enum _EPhysics_World_Constraint_Solver_Mode
 * typedef EPhysics_World_Constraint_Solver_Mode
 *
 * Identifies the worlds contact and
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Glossary_of_
 * Terms#Joint.2C_constraint"> joint constraint</a></b>
 * solver mode. By default
 * EPHYSICS_WORLD_SOLVER_USE_WARMSTARTING is the only enabled solver mode.
 *
 * @see ephysics_world_constraint_solver_mode_enable_set()
 * @see ephysics_world_constraint_solver_mode_enable_get()
 *
 * @ingroup EPhysics_World
 */
typedef enum _EPhysics_World_Constraint_Solver_Mode
{
   EPHYSICS_WORLD_SOLVER_RANDMIZE_ORDER = 1, /**< Randomize the order of solving the constraint rows*/
   EPHYSICS_WORLD_SOLVER_USE_WARMSTARTING = 4, /**< The PGS is an iterative algorithm where each iteration is based on the solution of previous iteration, if no warmstarting is used, the initial solution for PGS is set to zero each frame (by default this mode is enabled, disabling this mode the user can face a better performance depending on the amount of objects in the simulation)*/
   EPHYSICS_WORLD_SOLVER_USE_2_FRICTION_DIRECTIONS = 16, /**< While calculating a friction impulse consider this should be applied on both bodies (this mode cause a better stacking stabilization)*/
   EPHYSICS_WORLD_SOLVER_SIMD = 256, /**< Use a SSE optimized innerloop, using assembly intrinsics, this is implemented and can be enabled/disabled for Windows and Mac OSX versions, single-precision floating point, 32bit(disabled by default)*/
} EPhysics_World_Solver_Mode;

/**
 * @typedef EPhysics_World_Event_Cb
 *
 * EPhysics world event callback function signature.
 *
 * Callbacks can be registered for events like world deleting.
 *
 * @param data User data that will be set when registering the callback.
 * @param world Physics world.
 * @param event_info Data specific to a kind of event. Some types of events
 * don't have @p event_info.
 *
 * @see ephysics_world_event_callback_add() for more info.
 *
 * @ingroup EPhysics_World
 */
typedef void (*EPhysics_World_Event_Cb)(void *data, EPhysics_World *world, void *event_info);

/**
 * @brief
 * Create a new physics world.
 *
 * A new world will be created with set collision configuration,
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Collision_
 * Detection_and_Physics_FAQ#How_do_most_physics_engines_solve_constraints.3F">
 * constraint solver</a></b>,
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Broadphase">
 * broadphase</a></b>
 * interface and dispatcher.
 *
 * It can be paused / unpaused with @ref ephysics_world_running_set() and its
 * gravity can be changed with @ref ephysics_world_gravity_set().
 *
 * By default it starts with gravity y = 294 Evas coordinates per second ^ 2
 * and playing.
 *
 * If default updates between physics bodies and evas objects will be used
 * it's mandatory to set the size of the area to be rendered with
 * @ref ephysics_world_render_geometry_set().
 *
 * @return A new world or @c NULL, on errors.
 *
 * @see ephysics_world_del().
 *
 * @ingroup EPhysics_World
 */
EAPI EPhysics_World *ephysics_world_new(void);

/**
 * @brief
 * Set dimensions of rendered area to be take on account by default updates.
 *
 * By default it starts with null x, y, width and height.
 *
 * The physics world won't be limited, but boundaries can be added with:
 * @li @ref ephysics_body_top_boundary_add(),
 * @li @ref ephysics_body_bottom_boundary_add(),
 * @li @ref ephysics_body_left_boundary_add(),
 * @li @ref ephysics_body_right_boundary_add(),
 * @li @ref ephysics_body_front_boundary_add(),
 * @li @ref ephysics_body_back_boundary_add().
 *
 * @param world the world to be configured.
 * @param x Coordinate x of the top left point of rendered area, in pixels.
 * @param y Coordinate y of the top left point of rendered area, in pixels.
 * @param z Coordinate z of the rendered area, in pixels.
 * @param w rendered area width, in pixels.
 * @param h rendered area height, in pixels.
 * @param d rendered area depth, in pixels.
 *
 * @note The unit used for geometry is Evas coordinates.
 *
 * @see ephysics_body_event_callback_add() for more info.
 * @see ephysics_world_rate_get().
 * @see ephysics_world_render_geometry_get().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_render_geometry_set(EPhysics_World *world, Evas_Coord x, Evas_Coord y, Evas_Coord z, Evas_Coord w, Evas_Coord h, Evas_Coord d);

/**
 * @brief
 * Get dimensions of rendered area to be take on account by default updates.
 *
 * @param world the world to be configured.
 * @param x Coordinate x of the top left point of rendered area, in pixels.
 * @param y Coordinate y of the top left point of rendered area, in pixels.
 * @param z Coordinate z of the rendered area, in pixels.
 * @param w rendered area width, in pixels.
 * @param h rendered area height, in pixels.
 * @param d rendered area depth, in pixels.
 *
 * @see ephysics_world_render_geometry_set() for more information.
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_render_geometry_get(const EPhysics_World *world, Evas_Coord *x, Evas_Coord *y, Evas_Coord *z, Evas_Coord *w, Evas_Coord *h, Evas_Coord *d);

/**
 * @brief
 * Serializes the @p world to @p path.
 *
 * Save the dynamics world to a binary dump, a .bullet file.
 *
 * @note Should be used only for debugging purposes.
 *
 * @param world the world to be serialized.
 * @param path where the serialized world should be written to.
 *
 * @return EINA_TRUE on success, EINA_FALSE otherwise
 *
 * @ingroup EPhysics_World
 */
EAPI Eina_Bool ephysics_world_serialize(EPhysics_World *world, const char *path);

/**
 * @brief
 * Deletes a physics world.
 *
 * It will also delete all bodies associated to it.
 *
 * @param world The world to be deleted.
 *
 * @see ephysics_world_new() for more details.
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_del(EPhysics_World *world);

/**
 * @brief
 * Set running status of world.
 *
 * A world can be played / paused. When running, it will simulate the
 * physics step by step. When paused, it will stop simulation. Consequently
 * all the registered callbacks won't be called since no event will occur
 * (no collisions, no object updates).
 *
 * When a world is created it starts running.
 *
 * @param world The world to be played / paused.
 * @param running If @c EINA_TRUE it will play, otherwise it will pause.
 *
 * @see ephysics_world_running_get()
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_running_set(EPhysics_World *world, Eina_Bool running);

/**
 * @brief
 * Get running status of world.
 *
 * By default a world starts running.
 *
 * @param world The physics world.
 * @return @c EINA_TRUE if it's running, or @c EINA_FALSE if it's paused or on
 * error.
 *
 * @see ephysics_world_running_set() for more details.
 *
 * @ingroup EPhysics_World
 */
EAPI Eina_Bool ephysics_world_running_get(const EPhysics_World *world);

/**
 * @brief
 * Set the max sleeping time value.
 *
 * This value determines how long(in seconds) a rigid body under the linear and
 * angular threshold is supposed to be marked as sleeping. Default value is set
 * to 2.0.
 *
 * @param world The world to set the max sleeping time.
 * @param sleeping_time The max sleeping time to set to @p world.
 *
 * @see ephysics_world_max_sleeping_time_get()
 * @see ephysics_body_sleeping_threshold_set() for sleeping thresholds details.
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_max_sleeping_time_set(EPhysics_World *world, double sleeping_time);

/**
 * @brief
 * Get the max sleeping time value for @p world.
 *
 * @param world The world to get the max sleeping time from.
 * @return The max sleeping time from @p world.
 *
 * @see ephysics_world_max_sleeping_time_set()
 * @ingroup EPhysics_World
 */
EAPI double ephysics_world_max_sleeping_time_get(const EPhysics_World *world);

/**
 * @brief
 * Set world gravity in the 3 axes (x, y, z).
 *
 * Gravity will act over bodies with mass over all the time.
 *
 * By default values are 0, 294, 0 Evas Coordinates per second ^ 2
 * (9.8 m/s^2, since we've a default rate of 30 pixels).
 *
 * If you change the rate but wants to keep 9.8 m/s^2, you well need
 * to set world gravity with: 9.8 * new_rate.
 *
 * @param world The world object.
 * @param gx Gravity on x axis.
 * @param gy Gravity on y axis.
 * @param gz Gravity on z axis.
 *
 * @note The unit used for acceleration is Evas coordinates per second ^ 2.
 *
 * @see ephysics_world_gravity_get().
 * @see ephysics_world_rate_set().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_gravity_set(EPhysics_World *world, double gx, double gy, double gz);

/**
 * @brief
 * Set the number of iterations the
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Collision_
 * Detection_and_Physics_FAQ#How_do_most_physics_engines_solve_constraints.3F">
 * constraint solver</a></b>
 * will have for contact and
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Glossary_of_
 * Terms#Joint.2C_constraint">
 * joint constraints</a></b>.
 *
 * The default value is set to 10. The greater number of iterations more
 * quality and precise the result but with performance penalty.
 *
 * By default, the Projected Gauss Seidel
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Collision_
 * Detection_and_Physics_FAQ#How_do_most_physics_engines_solve_constraints.3F">
 * constraint solver</a></b>
 * is used for contact and
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Glossary_of_
 * Terms#Joint.2C_constraint">
 * joint constraints</a></b>.
 * The algorithm is an iterative LCP solver, informally known as 'sequential
 * impulse'.
 *
 * A reasonable range of iterations is from 4 (low quality, good performance)
 * to 20 (good quality, less but still reasonable performance).
 *
 * @param world The world to be set.
 * @param iterations The number of iterations to be set.
 *
 * @see ephysics_world_constraint_solver_iterations_get().
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_constraint_solver_iterations_set(EPhysics_World *world, int iterations);

/**
 * @brief
 * Get the number of iterations the
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Collision_
 * Detection_and_Physics_FAQ#How_do_most_physics_engines_solve_constraints.3F">
 * constraint solver</a></b>
 * will have for contact and
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Glossary_of_
 * Terms#Joint.2C_constraint">
 * joint constraints</a></b>.
 *
 * @param world The world to get number of iterations from.
 * @return the number of iterations set to @p world, or 0 on failure.
 *
 * @see ephysics_world_constraint_solver_iterations_set() for its meaning.
 * @ingroup EPhysics_World
 */
EAPI int ephysics_world_constraint_solver_iterations_get(const EPhysics_World *world);

/**
 * @brief
 * Enable or disable a
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Collision_
 * Detection_and_Physics_FAQ#How_do_most_physics_engines_solve_constraints.3F">
 * constraint solver</a></b>
 * mode to @p world. A world can operate
 * on several
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Collision_
 * Detection_and_Physics_FAQ#How_do_most_physics_engines_solve_constraints.3F">
 * constraint solver</a></b>
 * modes.
 *
 * @param world The world to be set.
 * @param solver_mode The solver mode to set.
 * @param enable If @c EINA_TRUE enable the mode, if EINA_FALSE, disable it.
 *
 * @see EPhysics_World_Solver_Mode for supported solver modes.
 * @see ephysics_world_constraint_solver_mode_enable_get()
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_constraint_solver_mode_enable_set(EPhysics_World *world, EPhysics_World_Solver_Mode solver_mode, Eina_Bool enable);

/**
 * @brief
 * Get the @p solver_mode status on @p world.
 *
 * @param world The world to be queried.
 * @param solver_mode The solver mode of interest.
 * @return EINA_TRUE if @p solver_mode is enabled, EINA_FALSE otherwise.
 *
 * @see ephysics_world_constraint_solver_mode_enable_set()
 * @ingroup EPhysics_World
 */
EAPI Eina_Bool ephysics_world_constraint_solver_mode_enable_get(const EPhysics_World *world, EPhysics_World_Solver_Mode solver_mode);

/**
 * @brief
 * Get world gravity values for axis x, y and z.
 *
 * @param world The world object.
 * @param gx Gravity on x axis.
 * @param gy Gravity on y axis.
 * @param gz Gravity on y axis.
 *
 * @see ephysics_world_gravity_set().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_gravity_get(const EPhysics_World *world, double *gx, double *gy, double *gz);

/**
 * @brief
 * Set rate between pixels on evas canvas and meters on ephysics world.
 *
 * It will be used by automatic updates of evas objects associated to
 * physics bodies.
 *
 * By default its value is 30 Evas coordinates (pixels) per meter.
 *
 * If you change the rate but wants to keep gravity as (0, 9.8 m/s^2),
 * you well need to set world gravity with: 9.8 * new_rate.
 * For this, use @ref ephysics_world_gravity_set();
 *
 * @param world The world object.
 * @param rate Rate between pixels and meters. Value must be > 0.
 *
 * @see ephysics_body_event_callback_add() for more info.
 * @see ephysics_world_rate_get().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_rate_set(EPhysics_World *world, double rate);

/**
 * @brief
 * Get rate between pixels on evas canvas and meters on ephysics world.
 *
 * @param world The world object.
 * @return The rate between pixels and meters.
 *
 * @see ephysics_world_rate_set() for details.
 *
 * @ingroup EPhysics_World
 */
EAPI double ephysics_world_rate_get(const EPhysics_World *world);

/**
 * @brief
 * Gets the world's bodies list.
 *
 * @param world The world object.
 * @return The list of bodies that belongs to this @p world.
 *
 * @note The list should be freed after usage.
 *
 * @see ephysics_body_cylinder_add().
 * @see ephysics_body_box_add().
 * @see ephysics_body_del().
 *
 * @ingroup EPhysics_World
 */
EAPI Eina_List *ephysics_world_bodies_get(const EPhysics_World *world);

/**
 * @brief
 * Get the camera used by an ephysics world.
 *
 * @param world The world object.
 * @return The camera.
 *
 * @see ephysics_camera_position_set().
 * @see ephysics_camera_body_track().
 *
 * @ingroup EPhysics_World
 */
EAPI EPhysics_Camera *ephysics_world_camera_get(const EPhysics_World *world);

/**
 * @brief
 * Register a callback to a type of physics world event.
 *
 * The registered callback will receives the world and extra user data that
 * can be passed.
 *
 * What follows is a list of details about each callback type:
 *
 *  - #EPHYSICS_CALLBACK_WORLD_DEL: Called just before a world is freed.
 * No event_info is passed to the callback.
 *
 *  - #EPHYSICS_CALLBACK_WORLD_STOPPED: Called when all the bodies
 * are stopped. No event_info is passed to the callback.
 *
 *  - #EPHYSICS_CALLBACK_WORLD_CAMERA_MOVED: Called if camera position changed
 * on physics simulation tick. Camera is passed as event_info to the callback.
 * Useful to move backgrounds, since objects would be already updated
 * considering camera's position.
 *
 * @param world The physics world.
 * @param type Type of callback to be listened by @p func.
 * @param func Callback function that will be called when event occurs.
 * @param data User data that will be passed to callback function. It won't
 * be used by ephysics in any way.
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_event_callback_add(EPhysics_World *world, EPhysics_Callback_World_Type type, EPhysics_World_Event_Cb func, const void *data);

/**
 * @brief
 * Unregister an ephysics world event callback.
 *
 * A previously added callback that match @p world, @p type and @p func
 * will be deleted.
 *
 * @param world The physics world.
 * @param type The type of callback to be unregistered.
 * @param func The callback function to be unregistered.
 * @return The user data passed when the callback was registered, or @c NULL
 * on error.
 *
 * @see ephysics_world_event_callback_add() for details.
 * @see ephysics_world_event_callback_del_full() if you need to match data
 * pointer.
 *
 * @ingroup EPhysics_World
 */
EAPI void *ephysics_world_event_callback_del(EPhysics_World *world, EPhysics_Callback_World_Type type, EPhysics_World_Event_Cb func);

/**
 * @brief
 * Unregister an ephysics world event callback matching data pointer.
 *
 * A previously added callback that match @p world, @p type, @p func
 * and @p data will be deleted.
 *
 * @param world The physics world.
 * @param type The type of callback to be unregistered.
 * @param func The callback function to be unregistered.
 * @param data The data pointer that was passed to the callback.
 * @return The user data passed when the callback was registered, or @c NULL
 * on error.
 *
 * @see ephysics_world_event_callback_add() for details.
 * @see ephysics_world_event_callback_del() if you don't need to match data
 * pointer.
 *
 * @ingroup EPhysics_World
 */
EAPI void *ephysics_world_event_callback_del_full(EPhysics_World *world, EPhysics_Callback_World_Type type, EPhysics_World_Event_Cb func, void *data);

/**
 * @brief
 * Set linear slop to be used by world.
 *
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Collision_
 * Detection_and_Physics_FAQ#How_do_most_physics_engines_solve_constraints.3F">
 * Constraint solver</a></b>
 * can be configured using some advanced settings, like
 * the solver slop factor.
 *
 * The default value is set to 0 with a small value results in a smoother
 * stabilization for stacking bodies.
 *
 * Linear slop on sequencial impulse
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Collision_
 * Detection_and_Physics_FAQ#How_do_most_physics_engines_solve_constraints.3F">
 * constraint solver</a></b>
 * is used as a factor for penetration. The penetration will the manifold
 * distance + linear slop.
 *
 * @param world The physics world.
 * @param linear_slop New linear slop value to be used by
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Collision_
 * Detection_and_Physics_FAQ#How_do_most_physics_engines_solve_constraints.3F">
 * constraint solver</a></b>
 * of physics engine.
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_linear_slop_set(EPhysics_World *world, double linear_slop);

/**
 * @brief
 * Get linear slop used by world.
 *
 * @param world The physics world.
 * @return Linear slop value used by
 * <b><a href="http://bulletphysics.org/mediawiki-1.5.8/index.php/Collision_
 * Detection_and_Physics_FAQ#How_do_most_physics_engines_solve_constraints.3F">
 * constraint solver</a></b>
 * of physics engine or 0 on failure.
 *
 * @see ephysics_world_linear_slop_set() for details.
 *
 * @ingroup EPhysics_World
 */
EAPI double ephysics_world_linear_slop_get(const EPhysics_World *world);

/**
 * @brief
 * Set world autodeleting bodies mode when they're outside of render area
 * by the top.
 *
 * It's useful when you don't care about bodies leaving the render
 * area set with @ref ephysics_world_render_geometry_set(), and don't think
 * they could / should return. So you can safely delete them and save resources.
 *
 * Also, it's useful if you have only a bottom border set with
 * @ref ephysics_body_top_boundary_add() and gravity set,
 * and want to listen for @ref EPHYSICS_CALLBACK_WORLD_STOPPED event.
 * If a body goes out of the render area, they will be acting by gravity
 * and won't collide to anything, so they could be moving forever and
 * world would never stop. For this case, enabling autodel for left and right
 * borders seems to be a good idea.
 *
 * @param world The physics world.
 * @param autodel If @c EINA_TRUE delete bodies when they are outside render
 * area, otherwise, don't delete.
 *
 * @see ephysics_world_bodies_outside_top_autodel_get().
 * @see ephysics_world_bodies_outside_bottom_autodel_set().
 * @see ephysics_world_bodies_outside_left_autodel_set().
 * @see ephysics_world_bodies_outside_right_autodel_set().
 * @see ephysics_world_bodies_outside_front_autodel_set().
 * @see ephysics_world_bodies_outside_back_autodel_set().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_bodies_outside_top_autodel_set(EPhysics_World *world, Eina_Bool autodel);

/**
 * @brief
 * Get world autodeleting bodies mode when they're outside of render area by
 * the top.
 *
 * @param world The physics world.
 * @return @c EINA_TRUE if bodies will be deleted or @c EINA_FALSE if they
 * won't, or on error.
 *
 * @see ephysics_world_bodies_outside_top_autodel_set() for details.
 *
 * @ingroup EPhysics_World
 */
EAPI Eina_Bool ephysics_world_bodies_outside_top_autodel_get(const EPhysics_World *world);

/**
 * @brief
 * Set world autodeleting bodies mode when they're outside of render area
 * by the bottom.
 *
 * @param world The physics world.
 * @param autodel If @c EINA_TRUE delete bodies when they are outside render
 * area, otherwise, don't delete.
 *
 * @see ephysics_world_bodies_outside_top_autodel_set() for more details.
 * @see ephysics_world_bodies_outside_bottom_autodel_get().
 * @see ephysics_world_bodies_outside_left_autodel_set().
 * @see ephysics_world_bodies_outside_right_autodel_set().
 * @see ephysics_world_bodies_outside_front_autodel_set().
 * @see ephysics_world_bodies_outside_back_autodel_set().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_bodies_outside_bottom_autodel_set(EPhysics_World *world, Eina_Bool autodel);

/**
 * @brief
 * Get world autodeleting bodies mode when they're outside of render area by
 * the bottom.
 *
 * @param world The physics world.
 * @return @c EINA_TRUE if bodies will be deleted or @c EINA_FALSE if they
 * won't, or on error.
 *
 * @see ephysics_world_bodies_outside_bottom_autodel_set() for details.
 *
 * @ingroup EPhysics_World
 */
EAPI Eina_Bool ephysics_world_bodies_outside_bottom_autodel_get(const EPhysics_World *world);

/**
 * @brief
 * Set world autodeleting bodies mode when they're outside of render area
 * by the right.
 *
 * @param world The physics world.
 * @param autodel If @c EINA_TRUE delete bodies when they are outside render
 * area, otherwise, don't delete.
 *
 * @see ephysics_world_bodies_outside_top_autodel_set() for more details.
 * @see ephysics_world_bodies_outside_right_autodel_get().
 * @see ephysics_world_bodies_outside_bottom_autodel_set().
 * @see ephysics_world_bodies_outside_left_autodel_set().
 * @see ephysics_world_bodies_outside_front_autodel_set().
 * @see ephysics_world_bodies_outside_back_autodel_set().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_bodies_outside_right_autodel_set(EPhysics_World *world, Eina_Bool autodel);

/**
 * @brief
 * Get world autodeleting bodies mode when they're outside of render area by
 * the right.
 *
 * @param world The physics world.
 * @return @c EINA_TRUE if bodies will be deleted or @c EINA_FALSE if they
 * won't, or on error.
 *
 * @see ephysics_world_bodies_outside_right_autodel_set() for details.
 *
 * @ingroup EPhysics_World
 */
EAPI Eina_Bool ephysics_world_bodies_outside_right_autodel_get(const EPhysics_World *world);

/**
 * @brief
 * Set world autodeleting bodies mode when they're outside of render area
 * by the left.
 *
 * @param world The physics world.
 * @param autodel If @c EINA_TRUE delete bodies when they are outside render
 * area, otherwise, don't delete.
 *
 * @see ephysics_world_bodies_outside_top_autodel_set() for more details.
 * @see ephysics_world_bodies_outside_left_autodel_get().
 * @see ephysics_world_bodies_outside_bottom_autodel_set().
 * @see ephysics_world_bodies_outside_right_autodel_set().
 * @see ephysics_world_bodies_outside_front_autodel_set().
 * @see ephysics_world_bodies_outside_back_autodel_set().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_bodies_outside_left_autodel_set(EPhysics_World *world, Eina_Bool autodel);

/**
 * @brief
 * Get world autodeleting bodies mode when they're outside of render area by
 * the left.
 *
 * @param world The physics world.
 * @return @c EINA_TRUE if bodies will be deleted or @c EINA_FALSE if they
 * won't, or on error.
 *
 * @see ephysics_world_bodies_outside_left_autodel_set() for details.
 *
 * @ingroup EPhysics_World
 */
EAPI Eina_Bool ephysics_world_bodies_outside_left_autodel_get(const EPhysics_World *world);

/**
 * @brief
 * Set world autodeleting bodies mode when they're outside of render area
 * by the front.
 *
 * @param world The physics world.
 * @param autodel If @c EINA_TRUE delete bodies when they are outside render
 * area, otherwise, don't delete.
 *
 * @see ephysics_world_bodies_outside_top_autodel_set() for more details.
 * @see ephysics_world_bodies_outside_left_autodel_get().
 * @see ephysics_world_bodies_outside_bottom_autodel_set().
 * @see ephysics_world_bodies_outside_right_autodel_set().
 * @see ephysics_world_bodies_outside_front_autodel_set().
 * @see ephysics_world_bodies_outside_back_autodel_set().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_bodies_outside_front_autodel_set(EPhysics_World *world, Eina_Bool autodel);

/**
 * @brief
 * Get world autodeleting bodies mode when they're outside of render area by
 * the front.
 *
 * @param world The physics world.
 * @return @c EINA_TRUE if bodies will be deleted or @c EINA_FALSE if they
 * won't, or on error.
 *
 * @see ephysics_world_bodies_outside_front_autodel_set() for details.
 *
 * @ingroup EPhysics_World
 */
EAPI Eina_Bool ephysics_world_bodies_outside_front_autodel_get(const EPhysics_World *world);

/**
 * @brief
 * Set world autodeleting bodies mode when they're outside of render area
 * by the back.
 *
 * @param world The physics world.
 * @param autodel If @c EINA_TRUE delete bodies when they are outside render
 * area, otherwise, don't delete.
 *
 * @see ephysics_world_bodies_outside_top_autodel_set() for more details.
 * @see ephysics_world_bodies_outside_left_autodel_get().
 * @see ephysics_world_bodies_outside_bottom_autodel_set().
 * @see ephysics_world_bodies_outside_right_autodel_set().
 * @see ephysics_world_bodies_outside_front_autodel_set().
 * @see ephysics_world_bodies_outside_back_autodel_set().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_bodies_outside_back_autodel_set(EPhysics_World *world, Eina_Bool autodel);

/**
 * @brief
 * Get world autodeleting bodies mode when they're outside of render area by
 * the back.
 *
 * @param world The physics world.
 * @return @c EINA_TRUE if bodies will be deleted or @c EINA_FALSE if they
 * won't, or on error.
 *
 * @see ephysics_world_bodies_outside_back_autodel_set() for details.
 *
 * @ingroup EPhysics_World
 */
EAPI Eina_Bool ephysics_world_bodies_outside_back_autodel_get(const EPhysics_World *world);

/**
 * @brief
 * Set world simulation's fixed time step and max number of sub steps
 * configuration.
 *
 * It's important that time step is always less than
 * @p max_sub_steps * @p fixed_time_step, otherwise you are losing time.
 * Mathematically:
 *
 * time step < @p max_sub_steps * @p fixed_time_step;
 *
 * If you're a using a very large time step
 * [say, five times the size of the fixed internal time step],
 * then you must increase the number of max sub steps to compensate for this,
 * otherwise your simulation is “losing” time.
 *
 * The time step may vary. Simulation ticks are called by an animator,
 * so, by default, time step is @c 1/30 secs. If you're using elementary,
 * default FPS configuration is 60 fps, i.e. time step is @c 1/60 secs.
 * You can change that setting a
 * different time with ecore_animator_frametime_set().
 *
 * Also, keep in mind
 * that if you're using CPU intense calculations maybe this framerate won't
 * be achieved, so the time step will be bigger. You need to define
 * what range of frames per seconds you need to support and configure
 * @p max_sub_steps and @p fixed_time_step according to this.
 *
 * By decreasing the size of @p fixed_time_step, you are increasing the
 * “resolution” of the simulation.
 *
 * If you are finding that your objects are moving very fast and escaping
 * from your walls instead of colliding with them, then one way to help fix
 * this problem is by decreasing @p fixed_time_step. If you do this,
 * then you will need to increase @p max_sub_steps to ensure the equation
 * listed above is still satisfied.
 *
 * The issue with this is that each internal “tick” takes an amount of
 * computation. More of them means your CPU will be spending more time on
 * physics and therefore less time on other stuff. Say you want twice the
 * resolution, you'll need twice the @p max_sub_steps, which could chew up
 * twice as much CPU for the same amount of simulation time.
 *
 * When you pass @p max_sub_steps > 1, it will interpolate movement for you.
 * This means that if your @p fixed_time_step is 3 units, and you pass
 * a timeStep of 4, then it will do exactly one tick, and estimate the
 * remaining movement by 1/3. This saves you having to do interpolation
 * yourself, but keep in mind that maxSubSteps needs to be greater than 1.
 *
 * By default @p fixed_time_step is 1/60 seconds and @p max_sub_steps is 3.
 *
 * @param world The physics world.
 * @param fixed_time_step size of the internal simulation step, in seconds.
 * @param max_sub_steps maximum number of steps that simulation is allowed
 * to take at each simulation tick.
 *
 * @note The unit used for time is seconds.
 *
 * @see ephysics_world_simulation_get().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_simulation_set(EPhysics_World *world, double fixed_time_step, int max_sub_steps);

/**
 * @brief
 * Get world simulation's fixed time step and max number of sub steps
 * configuration.
 *
 * @param world The physics world.
 * @param fixed_time_step size of the internal simulation step, in seconds.
 * @param max_sub_steps maximum number of steps that simulation is allowed
 * to take at each simulation tick.
 *
 * @see ephysics_world_simulation_set() for details.
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_simulation_get(const EPhysics_World *world, double *fixed_time_step, int *max_sub_steps);

/**
 * @brief
 * Set position of point light to be applied on the scene.
 *
 * It will perform lighting calculations on the evas map applied on evas
 * objects associated with all the bodies to have light applied over.
 *
 * This is used to apply lighting calculations (from a single light source)
 * to a given object. The R, G and B values of each vertex will be modified to
 * reflect the lighting based on the lixth point coordinates, the light color
 * and the ambient color, and at what angle the map is facing the light source.
 * A surface should have its points be declared in a clockwise fashion if the
 * face is "facing" towards you (as opposed to away from you) as faces have a
 * "logical" side for lighting.
 *
 * More details can be found on evas_map_util_3d_lighting() documentation,
 * since this function is used internally by EPhysics.
 *
 * There are two ways of setting a body to receive lighting. One is to simple
 * set all the bodies to be affected, with
 * @ref ephysics_world_light_all_bodies_set(). The other, is to set each body
 * individually, with @ref ephysics_body_light_set().
 *
 * By default, point light is set to position (0, 0, -200) and has white color
 * (r=255, g=255, b=255). The ambient color is black (r=0, g=0, b=0).
 * But no body will be affected. No change will be visible until
 * some bodies are set to be enlightened.
 *
 * @param world The physics world.
 * @param lx X coordinate in space of light point
 * @param ly Y coordinate in space of light point
 * @param lz Z coordinate in space of light point
 *
 * @see ephysics_world_point_light_position_get().
 * @see ephysics_world_point_light_color_set().
 * @see ephysics_world_ambient_light_color_set().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_point_light_position_set(EPhysics_World *world, Evas_Coord lx, Evas_Coord ly, Evas_Coord lz);

/**
 * @brief
 * Set color of point light to be applied on the scene.
 *
 * By default color of point light is r=255, g=255, b=255.
 *
 * @param world The physics world.
 * @param lr light red value (0 - 255)
 * @param lg light green value (0 - 255)
 * @param lb light blue value (0 - 255)
 *
 * @see ephysics_world_point_light_position_set() for more details.
 * @see ephysics_world_point_light_color_get().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_point_light_color_set(EPhysics_World *world, int lr, int lg, int lb);

/**
 * @brief
 * Set color of the ambient light to be applied on the scene.
 *
 * By default, ambient color is set to r=0, g=0, b=0.
 *
 * @param world The physics world.
 * @param ar ambient color red value (0 - 255)
 * @param ag ambient color green value (0 - 255)
 * @param ab ambient color blue value (0 - 255)
 *
 * @see ephysics_world_point_light_position_set() for more details.
 * @see ephysics_world_ambient_light_color_get().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_ambient_light_color_set(EPhysics_World *world, int ar, int ag, int ab);

/**
 * @brief
 * Get position of point light applied on the scene.
 *
 * @param world The physics world.
 * @param lx X coordinate in space of light point
 * @param ly Y coordinate in space of light point
 * @param lz Z coordinate in space of light point
 *
 * @see ephysics_world_point_light_position_set() for details.
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_point_light_position_get(const EPhysics_World *world, Evas_Coord *lx, Evas_Coord *ly, Evas_Coord *lz);

/**
 * @brief
 * Get color of point light applied on the scene.
 *
 * By default color of point light is r=255, g=255, b=255.
 *
 * @param world The physics world.
 * @param lr light red value (0 - 255)
 * @param lg light green value (0 - 255)
 * @param lb light blue value (0 - 255)
 *
 * @see ephysics_world_point_light_position_set() for more details.
 * @see ephysics_world_point_light_color_set().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_point_light_color_get(const EPhysics_World *world, int *lr, int *lg, int *lb);

/**
 * @brief
 * Set color of the ambient light to be applied on the scene.
 *
 * By default, ambient color is set to r=0, g=0, b=0.
 *
 * @param world The physics world.
 * @param ar ambient color red value (0 - 255)
 * @param ag ambient color green value (0 - 255)
 * @param ab ambient color blue value (0 - 255)
 *
 * @see ephysics_world_point_light_position_set() for more details.
 * @see ephysics_world_ambient_light_color_set().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_ambient_light_color_get(const EPhysics_World *world, int *ar, int *ag, int *ab);

/**
 * @brief
 * Set if light should be applied over all the bodies.
 *
 * @param world The physics world.
 * @param enable @c EINA_TRUE if light should be obligatory applied over
 * all the bodies, or @c EINA_FALSE if it only should be applied on bodies with
 * light property set.
 *
 * @see ephysics_world_point_light_position_set() for more details.
 * @see ephysics_world_light_all_bodies_get().
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_light_all_bodies_set(EPhysics_World *world, Eina_Bool enable);

/**
 * @brief
 * Get light setting regarding being applied over all the bodies.
 *
 * @param world The physics world.
 * @return @c EINA_TRUE if light will be obligatory applied over all the bodies,
 * or @c EINA_FALSE if it only will be applied on bodies with light property
 * set, or on error.
 *
 * @see ephysics_world_light_all_bodies_set() for details.
 *
 * @ingroup EPhysics_World
 */
EAPI Eina_Bool ephysics_world_light_all_bodies_get(const EPhysics_World *world);

/**
 * @brief
 * Enable / disable stacking based on bodies z coordinates.
 *
 * Evas objects associated to bodies will be restacked when it's enabled.
 * So if a body A has coordinates x = 10, y = 10, z = 8 and a body B
 * has coordinates x = 10, y = 10, z = 10, the evas object associated to B
 * will be displayed below the evas object associated to A.
 *
 * Evas objects will be restacked at each simulation tick. It's enabled by
 * default, and disabling it can lead to wrong scenarios when movement
 * on Z axis is enabled or when cloths are used.
 *
 * But disabling it can save performance, so if you won't face these
 * scenarios, it safe to disable it, since no evas object will be moved to
 * be below or above others.
 *
 * @param world The physics world.
 * @param enabled If @c EINA_TRUE, stacking based on Z coordinates will be
 * enabled, otherwise it will be disabled.
 *
 * @see ephysics_world_stack_enable_get()
 * @see ephysics_body_evas_object_set()
 *
 * @ingroup EPhysics_World
 */
EAPI void ephysics_world_stack_enable_set(EPhysics_World *world, Eina_Bool enabled);

/**
 * @brief
 * Get stacking status of world.
 *
 * Stacking based on bodies z coordinates can be enabled or disabled.
 *
 * @param world The physics world.
 * @return @c EINA_TRUE if it's running, or @c EINA_FALSE if it's paused or on
 * error.
 *
 * @see ephysics_world_stack_enable_set() for more details.
 *
 * @ingroup EPhysics_World
 */
EAPI Eina_Bool ephysics_world_stack_enable_get(const EPhysics_World *world);

/**
 * @}
 */

/**
 * @defgroup EPhysics_Body EPhysics Body
 * @ingroup EPhysics
 *
 * @{
 *
 * A body is a representation of an object inside a physics world.
 *
 * Bodies can have different shapes that can be created with:
 * @li @ref ephysics_body_cylinder_add();
 * @li @ref ephysics_body_box_add();
 * @li or @ref ephysics_body_shape_add().
 *
 * Also they can be soft bodies, that won't act as rigid bodies. They will
 * deform its shape under certain circumstances, like under collisions.
 * Soft bodies can be created with:
 * @li @ref ephysics_body_soft_cylinder_add();
 * @li @ref ephysics_body_soft_box_add();
 *
 * They can collide and have customizable properties, like:
 * @li mass, set with @ref ephysics_body_mass_set();
 * @li coefficient of restitution, set with
 * @ref ephysics_body_restitution_set();
 * @li and friction, set with @ref ephysics_body_friction_set().
 *
 * Bodies can have its position and size directly set by:
 * @ref ephysics_body_move();
 * @ref ephysics_body_resize();
 * @ref ephysics_body_geometry_set().
 *
 * Their rotation can be set directly with @ref ephysics_body_rotation_set().
 *
 * Also, they can have an associated evas object, done with
 * @ref ephysics_body_evas_object_set() function, being responsible for
 * updating its position and rotation, or letting a user callback be set
 * for this task with @ref ephysics_body_event_callback_add().
 *
 * Bodies can have velocity set with @ref ephysics_body_linear_velocity_set()
 * and @ref ephysics_body_angular_velocity_set().
 *
 * Also, bodies can have forces and impulses applied over them, and they will
 * be affected by gravity.
 *
 * Forces will be acting while they're set, changing bodies velocity over time.
 * Impulses are applied only once, modifying bodies velocity immediately to the
 * new value.
 *
 * Forces can be managed with:
 * @li @ref ephysics_body_central_force_apply();
 * @li @ref ephysics_body_torque_apply().
 * @li @ref ephysics_body_force_apply();
 * @li @ref ephysics_body_forces_clear();
 *
 * Impulses can be applied with:
 * @li @ref ephysics_body_central_impulse_apply();
 * @li @ref ephysics_body_torque_impulse_apply().
 * @li @ref ephysics_body_impulse_apply();
 *
 * Bodies can be removed from the world being directly deleted with
 * @ref ephysics_body_del() or when the world is deleted, case when all the
 * bodies belonging to it will be deleted as well. Evas objects associated
 * to these bodies won't be affected in any way, but they will stop being
 * moved or rotated.
 */

/**
 * @def EPHYSICS_BODY_MASS_STATIC
 * @brief Mass amount used to makes a body static.
 *
 * Body will be set with infinite mass, so it will be immovable.
 *
 * @see ephysics_body_mass_set() for details.
 */
#define EPHYSICS_BODY_MASS_STATIC (0.0)

/**
 * @def EPHYSICS_BODY_DENSITY_WOOD
 * @brief Density of wood in kg / m ^ 3.
 *
 * It can be set to a body with @ref ephysics_body_density_set().
 */
#define EPHYSICS_BODY_DENSITY_WOOD (680.0)
/**
 * @def EPHYSICS_BODY_DENSITY_IRON
 * @brief Density of iron in kg / m ^ 3.
 *
 * It can be set to a body with @ref ephysics_body_density_set().
 */
#define EPHYSICS_BODY_DENSITY_IRON (7400.0)
/**
 * @def EPHYSICS_BODY_DENSITY_CONCRETE
 * @brief Density of concrete in kg / m ^ 3.
 *
 * It can be set to a body with @ref ephysics_body_density_set().
 */
#define EPHYSICS_BODY_DENSITY_CONCRETE (2300.0)
/**
 * @def EPHYSICS_BODY_DENSITY_RUBBER
 * @brief Density of rubber in kg / m ^ 3.
 *
 * It can be set to a body with @ref ephysics_body_density_set().
 */
#define EPHYSICS_BODY_DENSITY_RUBBER (920.0)
/**
 * @def EPHYSICS_BODY_DENSITY_POLYSTYRENE
 * @brief Density of polystyrene in kg / m ^ 3.
 *
 * It can be set to a body with @ref ephysics_body_density_set().
 */
#define EPHYSICS_BODY_DENSITY_POLYSTYRENE (80.0)
/**
 * @def EPHYSICS_BODY_DENSITY_PLASTIC
 * @brief Density of plastic in kg / m ^ 3.
 *
 * It can be set to a body with @ref ephysics_body_density_set().
 */
#define EPHYSICS_BODY_DENSITY_PLASTIC (1300.0)

/**
 * @def EPHYSICS_BODY_FRICTION_WOOD
 * @brief Friction coefficient of wood.
 *
 * It can be set to a body with @ref ephysics_body_friction_set().
 */
#define EPHYSICS_BODY_FRICTION_WOOD (0.4)
/**
 * @def EPHYSICS_BODY_FRICTION_IRON
 * @brief Friction coefficient of iron.
 *
 * It can be set to a body with @ref ephysics_body_friction_set().
 */
#define EPHYSICS_BODY_FRICTION_IRON (0.8)
/**
 * @def EPHYSICS_BODY_FRICTION_CONCRETE
 * @brief Friction coefficient of concrete.
 *
 * It can be set to a body with @ref ephysics_body_friction_set().
 */
#define EPHYSICS_BODY_FRICTION_CONCRETE (0.65)
/**
 * @def EPHYSICS_BODY_FRICTION_RUBBER
 * @brief Friction coefficient of rubber.
 *
 * It can be set to a body with @ref ephysics_body_friction_set().
 */
#define EPHYSICS_BODY_FRICTION_RUBBER (0.75)
/**
 * @def EPHYSICS_BODY_FRICTION_POLYSTYRENE
 * @brief Friction coefficient of polystyrene.
 *
 * It can be set to a body with @ref ephysics_body_friction_set().
 */
#define EPHYSICS_BODY_FRICTION_POLYSTYRENE (0.5)
/**
 * @def EPHYSICS_BODY_FRICTION_PLASTIC
 * @brief Friction coefficient of plastic.
 *
 * It can be set to a body with @ref ephysics_body_friction_set().
 */
#define EPHYSICS_BODY_FRICTION_PLASTIC (0.35)

/**
 * @def EPHYSICS_BODY_RESTITUTION_WOOD
 * @brief Restitution coefficient of wood.
 *
 * It can be set to a body with @ref ephysics_body_restitution_set().
 */
#define EPHYSICS_BODY_RESTITUTION_WOOD (0.7)
/**
 * @def EPHYSICS_BODY_RESTITUTION_IRON
 * @brief Restitution coefficient of iron.
 *
 * It can be set to a body with @ref ephysics_body_restitution_set().
 */
#define EPHYSICS_BODY_RESTITUTION_IRON (0.85)
/**
 * @def EPHYSICS_BODY_RESTITUTION_CONCRETE
 * @brief Restitution coefficient of concrete.
 *
 * It can be set to a body with @ref ephysics_body_restitution_set().
 */
#define EPHYSICS_BODY_RESTITUTION_CONCRETE (0.75)
/**
 * @def EPHYSICS_BODY_RESTITUTION_RUBBER
 * @brief Restitution coefficient of rubber.
 *
 * It can be set to a body with @ref ephysics_body_restitution_set().
 */
#define EPHYSICS_BODY_RESTITUTION_RUBBER (0.3)
/**
 * @def EPHYSICS_BODY_RESTITUTION_POLYSTYRENE
 * @brief Restitution coefficient of polystyrene.
 *
 * It can be set to a body with @ref ephysics_body_restitution_set().
 */
#define EPHYSICS_BODY_RESTITUTION_POLYSTYRENE (0.5)
/**
 * @def EPHYSICS_BODY_RESTITUTION_PLASTIC
 * @brief Restitution coefficient of plastic.
 *
 * It can be set to a body with @ref ephysics_body_restitution_set().
 */
#define EPHYSICS_BODY_RESTITUTION_PLASTIC (0.6)

/**
 * @enum _EPhysics_Body_Cloth_Anchor_Side
 * @typedef EPhysics_Body_Cloth_Anchor_Side
 *
 * Identifier of cloth anchor sides.
 *
 * @see ephysics_body_cloth_anchor_full_add()
 *
 * @ingroup EPhysics_Body
 */
typedef enum _EPhysics_Body_Cloth_Anchor_Side
{
  EPHYSICS_BODY_CLOTH_ANCHOR_SIDE_LEFT,
  EPHYSICS_BODY_CLOTH_ANCHOR_SIDE_RIGHT,
  EPHYSICS_BODY_CLOTH_ANCHOR_SIDE_TOP,
  EPHYSICS_BODY_CLOTH_ANCHOR_SIDE_BOTTOM,
  EPHYSICS_BODY_CLOTH_ANCHOR_SIDE_LAST,
} EPhysics_Body_Cloth_Anchor_Side;

/**
 * @enum _EPhysics_Body_Face
 * @typedef EPhysics_Body_Face
 *
 * Define in which body's face the evas object should be set.
 *
 * @see ephysics_body_face_evas_object_set()
 * @see ephysics_body_face_evas_object_unset()
 * @see ephysics_body_face_evas_object_get()
 *
 * @ingroup EPhysics_Body
 */
typedef enum _EPhysics_Body_Face
{
  EPHYSICS_BODY_BOX_FACE_MIDDLE_FRONT,
  EPHYSICS_BODY_BOX_FACE_MIDDLE_BACK,
  EPHYSICS_BODY_BOX_FACE_FRONT,
  EPHYSICS_BODY_BOX_FACE_BACK,
  EPHYSICS_BODY_BOX_FACE_LEFT,
  EPHYSICS_BODY_BOX_FACE_RIGHT,
  EPHYSICS_BODY_BOX_FACE_TOP,
  EPHYSICS_BODY_BOX_FACE_BOTTOM,

  EPHYSICS_BODY_CLOTH_FACE_FRONT,
  EPHYSICS_BODY_CLOTH_FACE_BACK,

  EPHYSICS_BODY_CYLINDER_FACE_MIDDLE_FRONT,
  EPHYSICS_BODY_CYLINDER_FACE_MIDDLE_BACK,
  EPHYSICS_BODY_CYLINDER_FACE_FRONT,
  EPHYSICS_BODY_CYLINDER_FACE_BACK,
  EPHYSICS_BODY_CYLINDER_FACE_CURVED,

  EPHYSICS_BODY_SPHERE_FACE_FRONT,
  EPHYSICS_BODY_SPHERE_FACE_BACK,

  EPHYSICS_BODY_FACE_LAST,
} EPhysics_Body_Face;

/**
 * @typedef EPhysics_Body_Collision
 *
 * Body collision wraps collision informations.
 *
 * EPhysics_Body_Collision is used on EPHYSICS_CALLBACK_BODY_COLLISION callback
 * and is mostly interested to hold informations like:
 * @li contact_body - the body which the collision occurred against;
 * @li position - points the position where the collision happened;
 *
 * @see ephysics_body_collision_position_get()
 * @see ephysics_body_collision_contact_body_get()
 * @see EPHYSICS_CALLBACK_BODY_COLLISION and @ref
 * ephysics_body_event_callback_add() for collision callback.
 * @ingroup EPhysics_Body
 */
typedef struct _EPhysics_Body_Collision EPhysics_Body_Collision;

/**
 * @enum _EPhysics_Callback_Body_Type
 * @typedef EPhysics_Callback_Body_Type
 *
 * Identifier of callbacks to be set for EPhysics bodies.
 *
 * @see ephysics_body_event_callback_add()
 * @see ephysics_body_event_callback_del()
 * @see ephysics_body_event_callback_del_full()
 *
 * @ingroup EPhysics_Body
 */
typedef enum _EPhysics_Callback_Body_Type
{
   EPHYSICS_CALLBACK_BODY_UPDATE, /**< Body being updated */
   EPHYSICS_CALLBACK_BODY_COLLISION, /**< Body collided with other body */
   EPHYSICS_CALLBACK_BODY_DEL, /**< Body being deleted (called before free) */
   EPHYSICS_CALLBACK_BODY_STOPPED, /**< Body is not moving any more */
   EPHYSICS_CALLBACK_BODY_LAST, /**< kept as sentinel, not really an event */
} EPhysics_Callback_Body_Type; /**< The types of events triggering a callback */

/**
 * @enum _EPhysics_Body_Material
 * @typedef EPhysics_Body_Material
 *
 * EPhysics bodies materials. Each material has specific properties to be
 * applied on the body, as density, friction and restitution.
 *
 * @see ephysics_body_material_set() for details.
 *
 * @ingroup EPhysics_Body
 */
typedef enum _EPhysics_Body_Material
{
   EPHYSICS_BODY_MATERIAL_CUSTOM, /**< Custom properties set by the user */
   EPHYSICS_BODY_MATERIAL_CONCRETE, /**< Density:2300,Fric:0.65,Rest:0.75 */
   EPHYSICS_BODY_MATERIAL_IRON, /**< Density:7400,Fric:0.8,Rest:0.85 */
   EPHYSICS_BODY_MATERIAL_PLASTIC, /**< Density:1300,Fric:0.35,Rest:0.6 */
   EPHYSICS_BODY_MATERIAL_POLYSTYRENE, /**< Density:80,Fric:0.5,Rest:0.5*/
   EPHYSICS_BODY_MATERIAL_RUBBER, /**< Density:920,Fric:0.75,Rest:0.3*/
   EPHYSICS_BODY_MATERIAL_WOOD, /**< Density:680,Fric:0.4,Rest:0.7*/
   EPHYSICS_BODY_MATERIAL_LAST, /**< kept as sentinel, not really a material */
} EPhysics_Body_Material; /**< The types of materials to be set on a body */

/**
 * @typedef EPhysics_Body_Event_Cb
 *
 * EPhysics body event callback function signature.
 *
 * Callbacks can be registered for events like body updating or deleting.
 *
 * @param data User data that will be set when registering the callback.
 * @param body Physics body.
 * @param event_info Data specific to a kind of event. Some types of events
 * don't have @p event_info.
 *
 * @see ephysics_body_event_callback_add() for more info.
 *
 * @ingroup EPhysics_Body
 */
typedef void (*EPhysics_Body_Event_Cb)(void *data, EPhysics_Body *body, void *event_info);

/**
 * @brief
 * Set the soft body hardness percentage.
 *
 * The hardness percentage will define how the soft body is supposed to deform,
 * its default is set to 100%. The soft body mass will also interfere on soft
 * body deformation, so bare in mind that the bodies mass must also be changed
 * to have different deformation results.
 *
 * Valid values vary from 0 to 100.
 *
 * @param body The body to be set.
 * @param hardness The percentage of deformation.
 *
 * @see ephysics_body_soft_body_hardness_get()
 * @see ephysics_body_mass_set() form body mass changing.
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_soft_body_hardness_set(EPhysics_Body *body, double hardness);

/**
 * @brief
 * Get the soft body hardness percentage.
 *
 * @param body The body of interest.
 * @return The deformation percentage.
 *
 * @see ephysics_body_soft_body_hardness_set()
 *
 * @ingroup EPhysics_Body
 */
EAPI double ephysics_body_soft_body_hardness_get(const EPhysics_Body *body);

/**
 * @brief
 * Set the soft body anchor hardness percentage.
 *
 * The anchor hardness percentage(together with general hardness settings
 * set with ephysics_body_soft_body_hardness_set()) will define how the soft
 * body is supposed to deform.
 *
 * By default EPhysics will calculate the anchor hardness depending on the
 * general hardness settings, by default it`s set to 70% of general hardness on
 * soft body and a fixed 80% for cloths.
 *
 * Anchor hardness will result on a contrary force to impulse and velocities
 * applied to soft bodies. So it implies on force reduction.
 *
 * @note Since it`s a percentage value @p hardness will range from 0 - 100.
 *
 * @param body The body to be set.
 * @param hardness The hardness to be set to @p body.
 *
 * @see ephysics_body_soft_body_hardness_set() for general hardness.
 * @see ephysics_body_soft_body_anchor_hardness_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_soft_body_anchor_hardness_set(EPhysics_Body *body, double hardness);

/**
 * @brief
 * Get the soft body anchor hardnees percentage.
 *
 * @param body The body to get the anchor hardness percentage from.
 * @return The anchor hardness percentage on success -1 on failure.
 *
 * @see ephysics_body_soft_body_anchor_hardness_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI double ephysics_body_soft_body_anchor_hardness_get(EPhysics_Body *body);

/**
 * @brief
 * Set the drag coefficient of a soft body.
 *
 * Drag coefficient is a dimensionless quantity used to quantify an objects drag
 * or resistance in the environment - like air or water resistance. It is used in
 * the drag equation, where a lower drag coefficient indicates the object will
 * have less aerodynamic or hydrodynamic drag.
 *
 * The drag coefficient is defined as:
 *
 * cd = 2Fd / (pv ^ 2)A
 *
 * Where:
 *
 * - @c Fd is the drag force, which is by definition the force component in the
 * direction of the flow velocity;
 * - @c p is the mass density;
 * - @c v is the speed;
 * - @c A is the reference area;
 *
 * The reference area depends on what type of drag coefficient is being measured.
 *
 * @note default value set to 0.
 *
 * @param body The body to be set.
 * @param coefficient  The drag coefficient.
 *
 * @see ephysics_body_soft_body_drag_coefficient_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_soft_body_drag_coefficient_set(EPhysics_Body *body, double coefficient);

/**
 * @brief
 * Get the drag coefficient of a soft body.
 *
 * @param body The body to get the drag coefficient from.
 * @return The drag coefficient set to @p body on success, -1 on failure.
 *
 * @see ephysics_body_soft_body_drag_coefficient_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI double ephysics_body_soft_body_drag_coefficient_get(const EPhysics_Body *body);

/**
 * @brief
 * Set the soft body dragging status.
 *
 * While dragging a soft body the user may want to freeze a specific trimesh
 * face, after calling this function EPhysics will do freeze the @p triangle
 * until it gets a call to unset it with
 * ephysics_body_soft_body_dragging_unset().
 *
 * @note Freezing a specific trimesh face means no forces are applied to it, no
 * gravity enforced, that's @p triangle will have no mass until it dragging
 * gets unset.
 *
 * @param body The body of interest.
 * @param triangle The triangle to freeze.
 *
 * @see ephysics_body_soft_body_dragging_unset().
 * @see ephysics_body_soft_body_triangle_index_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_soft_body_dragging_set(EPhysics_Body *body, int triangle);

/**
 * @brief
 * Unset the soft body dragging status.
 *
 * This function will tell EPhysics to not freeze - the previously dragging
 * triangle set - any more.
 *
 * @param body The body to unset the dragging status.
 *
 * @see ephysics_body_soft_body_dragging_set() for dragging details.
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_soft_body_dragging_unset(EPhysics_Body *body);

/**
 * @brief
 * Get the triangle index of a soft body in @p x and @p y.
 *
 * Given a point in @p x and @p y a ray cast is performed and if a triangle is
 * found its index is returned.
 *
 * @param body The body to get the triangle index from.
 * @param x The x coord.
 * @param y The y coord.
 * @return -1 If no triangle is found, a triangle index otherwise.
 *
 * @see ephysics_body_soft_body_triangle_move().
 *
 * @ingroup EPhysics_Body
 */
EAPI int ephysics_body_soft_body_triangle_index_get(EPhysics_Body *body, Evas_Coord x, Evas_Coord y);

/**
 * @brief
 * Get the slice index of a soft body based on its slice`s Evas Object.
 *
 * Registering a mouse event callback on an associated evas object one can get
 * the clicked slice evas object. With that pointer the user can get the slice
 * index based on its related evas object.
 *
 * @param body The body to get the slice index from.
 * @param slice The slice evas object.
 * @return The slice index on success, -1 otherwise.
 *
 * @see ephysics_body_soft_body_triangle_index_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI int ephysics_body_soft_body_slice_index_get(EPhysics_Body *body, Evas_Object *slice);

/**
 * @brief
 * Add a soft sphere.
 *
 * Add a new soft 3d sphere to the simulation. The @p granularity defines how
 * many triangles are to be added.
 *
 * @note if no @p granularity is informed(i.e @p granularity = 0) the soft body
 * will be created with a triangle mesh of 100.
 *
 * @param world The world the new soft sphere is to be added.
 * @param granularity How many triangles the soft body triangle mesh must have.
 * @return a new body or @c NULL on errors.
 *
 * @see ephysics_body_del().
 * @see ephysics_body_evas_object_set().
 * @see ephysics_body_face_evas_object_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_soft_sphere_add(EPhysics_World *world, int granularity);

/**
 * @brief
 * Get a list of triangles indexes inside an area.
 *
 * Get a list of triangles indexes given an area defined by @p x, @p y, @p z, @p
 * w, @p h and @p d, the z axis components are represented by @p x and @p d
 * where all triangles between @p z and @p d are considered, that's triangles
 * with their z component greater than @p z and smaller than @p d.
 *
 * @note EPhysics will not free the returned list, remember to do so.
 *
 * @param body The body to get triangles indexes from.
 * @param x The x component.
 * @param y The y component.
 * @param z The z component.
 * @param w The w component.
 * @param h The h component.
 * @param d The d component.
 *
 * @return NULL on errors or no triangles found, a list of triangles indexes
 * otherwhise.
 *
 * @see ephysics_body_soft_body_triangle_index_get().
 * @see ephysics_body_soft_body_slice_index_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI Eina_List *ephysics_body_soft_body_triangles_inside_get(const EPhysics_Body *body, Evas_Coord x, Evas_Coord y, Evas_Coord z, Evas_Coord w, Evas_Coord h, Evas_Coord d);

/**
 * @brief
 * Apply an impulse on a given soft body triangle.
 *
 * The impulse is equal to the change of momentum of the body.
 * Impulse is the product of the force over the time this force is applied. In
 * ephysics case, it would be the time of a tick, so it behaves just summing
 * current linear velocity to impulse per mass(per triangle mass).
 *
 * When a impulse is applied over a body, it will have its velocity changed. This
 * impulse will be applied on body's specified triangle @p idx, so it won't
 * imply in rotating the body.
 *
 * @note Impulse is measured in kg * p / s.
 *
 * @param body The body to apply impulse to.
 * @param idx The soft body triangle index.
 * @param x The axis @p x component of impulse.
 * @param y The axis @p y component of impulse
 * @param z The axis @p z component of impulse
 *
 * @see ephysics_body_soft_body_triangle_index_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_soft_body_triangle_impulse_apply(EPhysics_Body * body, int idx, double x, double y, double z);

/**
 * @brief
 * Apply impulse in a list of triangles.
 *
 * Apply impulse in a list of triangles all at once considering the same impulse
 * values on @p x, @p y and @p z.
 *
 * @param body The body to apply impulse.
 * @param triangles A list of triangles indexes.
 * @param x The axis @p x component of impulse.
 * @param y The axis @p y component of impulse.
 * @param z The axis @p z component of impulse.
 *
 * @see ephysics_body_soft_body_triangle_impulse_apply() to see about impulse
 * applying on soft bodies.
 * @see ephysics_body_soft_body_triangles_inside_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_soft_body_triangle_list_impulse_apply(EPhysics_Body *body, Eina_List *triangles, double x, double y, double z);

/**
 * @brief
 * Set the soft body number of position iterations.
 *
 * Both soft body and cloth can have its number of position iterations changed.
 * The number of position iterations will change how many time the physics
 * engine
 * will iterate the position solver, a greater value will change deformation
 * behaves and how hard the soft body looks like. The greater position
 * iterations the harder the soft body will be.
 *
 * @note For soft bodies the default value is set to 1, and for cloth it's set
 * to the number of rows / 5;
 *
 * @param body The body to be set.
 * @param iterations The number of iterations.
 *
 * @see ephysics_body_cloth_add() for more informations about cloth.
 * @see ephysics_body_soft_body_position_iterations_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_soft_body_position_iterations_set(EPhysics_Body *body, int iterations);

/**
 * @brief
 * Get the soft body number of position iterations.
 *
 * @param body The body to get the number os position iterations from.
 * @return The number of position solver iterations of a soft @p body.
 *
 * @see ephysics_body_soft_body_position_iterations_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI int ephysics_body_soft_body_position_iterations_get(EPhysics_Body *body);

/**
 * @brief
 * Move a body's triangle.
 *
 * Move the triangle of @p idx of @p body to @p x, @p y and @p z.
 *
 * @param body The body of interest.
 * @param idx The triangle index.
 * @param x The x coordinate.
 * @param y The y coordinate.
 * @param z The z coordinate.
 *
 * @see ephysics_body_soft_body_triangle_index_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_soft_body_triangle_move(EPhysics_Body *body, int idx, Evas_Coord x, Evas_Coord y, Evas_Coord z);

/**
 * @brief
 * Add new bending constraints to some @p body.
 *
 * Bending constraints define how a soft body is to be deformeable. In fact a
 * bending constraints represents a link between a soft body mesh triangle and
 * other. The hardness property is used to define the bending constraint of
 * those new links.
 *
 * By default EPhysics create a new soft body or cloth with a single bending
 * constraint.
 *
 * @param body The body to add bending constraints to.
 * @param number The number of bending constraints to be added, it must be
 * greater than 0.
 *
 * @see ephysics_body_soft_body_hardness_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_soft_body_bending_constraints_add(EPhysics_Body *body, int number);

/**
 * @brief
 * Create a new sphere physics body.
 *
 * Its collision shape will be a sphere of diameter 1. To change its size @ref
 * ephysics_body_geometry_set(), @p ephysics_body_resize() should be used.
 *
 * Any evas object can be associated to it with @p
 * ephysics_body_evas_object_set(), and it will collid as a sphere(even if
 * you`ve associated an evas rectangle).
 *
 * For deformable sphere use @p ephysics_body_soft_sphere_add() instead.
 *
 * @param world The world this body will belong to.
 * @return a new body or @c NULL, on errors.
 *
 * @see ephysics_body_del().
 * @see ephysics_body_evas_object_set().
 * @see ephysics_body_face_evas_object_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_sphere_add(EPhysics_World *world);

/**
 * @brief
 * Create a new cylinder physics body.
 *
 * Its collision shape will be a cylinder of diameter 1. To change it's size
 * @ref ephysics_body_geometry_set() should be used.
 *
 * Any evas object can be associated to it with
 * @ref ephysics_body_evas_object_set(),
 * and it will collide as a cylinder (even if you have an evas rectangle).
 *
 * If a cylinder that could have its shape deformed is required, use
 * @ref ephysics_body_soft_cylinder_add().
 *
 * @param world The world this body will belongs to.
 * @return a new body or @c NULL, on errors.
 *
 * @see ephysics_body_del().
 * @see ephysics_body_evas_object_set().
 * @see ephysics_body_face_evas_object_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_cylinder_add(EPhysics_World *world);

/**
 * @brief
 * Create a new deformable cylinder physics body.
 *
 * Its collision shape will be a cylinder of diameter 1. To change it's size
 * @ref ephysics_body_geometry_set() should be used.
 *
 * Any evas object can be associated to it with
 * @ref ephysics_body_evas_object_set(),
 * and it will collide and deform as a cylinder (even if you have an evas
 * rectangle).
 *
 * Just like rotation, deformation will be applied on associated
 * evas object using evas map.
 *
 * @note When working with soft bodies it's importante to adjust the
 * simulation's fixed time step due its multi point nature.
 *
 * For a rigid cylinder, check @ref ephysics_body_cylinder_add().
 *
 * @param world The world this body will belongs to.
 * @return a new body or @c NULL, on errors.
 *
 * @see ephysics_body_del().
 * @see ephysics_body_evas_object_set().
 * @see ephysics_body_face_evas_object_set().
 * @see ephysics_world_simulation_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_soft_cylinder_add(EPhysics_World *world);

/**
 * @brief
 * Create a new box physics body.
 *
 * Its collision shape will be a box of dimensions 1 on all the axes.
 * To change it's size @ref ephysics_body_geometry_set() should be used.
 *
 * If a box that could have its shape deformed is required, use
 * @ref ephysics_body_soft_box_add().
 *
 * @param world The world this body will belongs to.
 * @return a new body or @c NULL, on errors.
 *
 * @see ephysics_body_del().
 * @see ephysics_body_evas_object_set().
 * @see ephysics_body_face_evas_object_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_box_add(EPhysics_World *world);

/**
 * @brief
 * Create a new deformable box physics body.
 *
 * Its collision shape will be a box of dimensions 1 on all the axes.
 * To change it's size @ref ephysics_body_geometry_set() should be used.
 *
 * Just like rotation, deformation will be applied on associated
 * evas object using evas map.
 *
 * @note When working with soft bodies it's importante to adjust the
 * simulation's fixed time step due its multi point nature.
 *
 * For a rigid cylinder, check @ref ephysics_body_cylinder_add().
 *
 * @param world The world this body will belong to.
 * @return a new body or @c NULL on errors.
 *
 * @see ephysics_body_del().
 * @see ephysics_body_evas_object_set().
 * @see ephysics_body_face_evas_object_set().
 * @see ephysics_world_simulation_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_soft_box_add(EPhysics_World *world);

/**
 * @brief
 * Create a new deformable cloth physics body.
 *
 * A cloth has its points of deformation conceptually split into rows and
 * columns where every square is also split into two triangles - afore named
 * nodes. To fine tune the deformation one can increase this granularity by
 * increasing the number of  @p rows and @p columns.
 *
 * By default - if passed 0 as @p rows and @p columns - EPhysics creates a cloth
 * with 15 rows and 15 columns, these default values will generally fit the most
 * common scenarios.
 *
 * If the informed @p rows is of 0 then the default value - of 15 - is
 * assumed. The same is true for @p columns.
 *
 * @param world The world this body will belong to.
 * @param rows The number os rows.
 * @param columns The number of columns.
 * @return a new body or @c NULL on erros.
 *
 * @see ephysics_body_del().
 * @see ephysics_body_evas_object_set().
 * @see ephysics_body_face_evas_object_set().
 * @see ephysics_world_simulation_set().
 * @see ephysics_body_cloth_anchor_add().
 * @see ephysics_body_cloth_anchor_full_add().
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_cloth_add(EPhysics_World *world, unsigned short rows, unsigned short columns);

/**
 * @brief
 * Anchors a cloth with a rigid body.
 *
 * All the informed @p side of @p body1 will be anchored to @p body2 wherever
 * it's in time of anchoring. That is, all the nodes in the informed "edge".
 *
 * An anchor assumes the @p body1 positions, if it's 20px far from @p body2 then
 * this distance is always kept, moving @p body1 or @p body2 will respect a 20px
 * difference.
 *
 * @param body1 The cloth body to be anchored.
 * @param body2 The body to be anchored to.
 * @param side The side to be anchored.
 *
 * @see ephysics_body_cloth_anchor_add().
 * @see ephysics_body_cloth_anchor_del().
 * @see ephysics_body_cloth_add() to know more about the cloth physics
 * representation.
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_cloth_anchor_full_add(EPhysics_Body *body1, EPhysics_Body *body2, EPhysics_Body_Cloth_Anchor_Side side);

/**
 * @brief
 * Anchors an arbitrary cloth's node with a rigid body.
 *
 * The informed @p node of @p body1 will be anchored to @p body2 wherever it's
 * in time of anchoring.
 *
 * @see ephysics_body_cloth_add() to know more about the cloth physics
 * representation, nodes and so on.
 *
 * An anchor assumes the @p body1 positions, if it's 20px far from @p body2 then
 * this distance is always kept, moving @p body1 or @p body2 will respect a 20px
 * difference.
 *
 * @param body1 The cloth body to be anchored.
 * @param body2 The body to be anchored to.
 * @param node The node index to be anchored.
 *
 * @see ephysics_body_cloth_anchor_full_add().
 * @see ephysics_body_cloth_anchor_del().

 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_cloth_anchor_add(EPhysics_Body *body1, EPhysics_Body *body2, int node);

/**
 * @brief
 * Removes the anchors in a cloth body.
 *
 * @param body The body to delete anchors from.
 *
 * @see ephysics_body_cloth_anchor_full_add().
 * @see ephysics_body_cloth_anchor_add().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_cloth_anchor_del(EPhysics_Body *body);

/**
 * @brief
 * Create a new physics body using a custom shape.
 *
 * Its collision shape will be a convex shape that has all the points
 * added to this @p shape. A shape can be created with
 * @ref ephysics_shape_new().
 *
 * To change it's size @ref ephysics_body_geometry_set() should be used,
 * so it can be deformed on x, y and z axes.
 *
 * The center of mass of this body can be get with
 * @ref ephysics_body_center_mass_get().
 *
 * @param world The world this body will belongs to.
 * @param shape The custom shape to be used.
 * @return a new body or @c NULL, on errors.
 *
 * @see ephysics_body_del().
 * @see ephysics_body_evas_object_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_shape_add(EPhysics_World *world, EPhysics_Shape *shape);

/**
 * @brief
 * Create a physic top boundary.
 *
 * A physic top boundary will limit the bodies area and placed on top edge of
 * worlds render geometry - defined with
 * @ref ephysics_world_render_geometry_set().
 *
 * @param world The world this body will belong to.
 * @return a new body or @c NULL, on erros.
 * @see ephysics_world_render_geometry_set()
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_top_boundary_add(EPhysics_World *world);

/**
 * @brief
 * Create a physic bottom boundary.
 *
 * A physic bottom boundary will limit the bodies area and placed on bottom
 * edge of worlds render geometry - defined with
 * @ref ephysics_world_render_geometry_set().
 *
 * @param world The world this body will belong to.
 * @return a new body or @c NULL, on erros.
 * @see ephysics_world_render_geometry_set()
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_bottom_boundary_add(EPhysics_World *world);

/**
 * @brief
 * Create a physic left boundary.
 *
 * A physic left boundary will limit the bodies area and placed right o the
 * left edge of worlds render geometry - defined with
 * @ref ephysics_world_render_geometry_set().
 *
 * @param world The world this body will belong to.
 * @return a new body or @c NULL, on erros.
 * @see ephysics_world_render_geometry_set()
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_left_boundary_add(EPhysics_World *world);

/**
 * @brief
 * Create a physic right boundary.
 *
 * A physic right boundary will limit the bodies area and placed right o the
 * right edge of worlds render geometry - defined with
 * @ref ephysics_world_render_geometry_set().
 *
 * @param world The world this body will belong to.
 * @return a new body or @c NULL, on erros.
 * @see ephysics_world_render_geometry_set()
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_right_boundary_add(EPhysics_World *world);

/**
 * @brief
 * Create a physic front boundary.
 *
 * A physic front boundary will limit the bodies area and placed on the
 * front of worlds render geometry - defined with
 * @ref ephysics_world_render_geometry_set().
 * It is placed on x-y plane, from x to x + width, from y to y + height.
 *
 * @param world The world this body will belong to.
 * @return a new body or @c NULL, on erros.
 * @see ephysics_world_render_geometry_set()
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_front_boundary_add(EPhysics_World *world);

/**
 * @brief
 * Create a physic back boundary.
 *
 * A physic front boundary will limit the bodies area and placed on the
 * back of worlds render geometry - defined with
 * @ref ephysics_world_render_geometry_set().
 * It is placed on x-y plane, from x to x + width, from y to y + height.
 *
 * @param world The world this body will belong to.
 * @return a new body or @c NULL, on erros.
 * @see ephysics_world_render_geometry_set()
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_back_boundary_add(EPhysics_World *world);

/**
 * @brief
 * Delete a physics body.
 *
 * This function will remove this body from its world and will
 * free all the memory used. It won't delete or modify an associated evas
 * object, what can be done with @ref ephysics_body_evas_object_set(). So after
 * it is removed the evas object will stop being updated, but will continue
 * to be rendered on canvas.
 *
 * @param body The body to be deleted.
 *
 * @see ephysics_body_box_add().
 * @see ephysics_body_cylinder_add().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_del(EPhysics_Body *body);

/**
 * @brief
 * Get the world a body belongs to.
 *
 * It will return the world where the body was added to.
 *
 * @param body The physics body.
 * @return The world, or @c NULL on error.
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_World *ephysics_body_world_get(const EPhysics_Body *body);

/**
 * @brief
 * Set an evas object to a physics body.
 *
 * It will create a direct association between a physics body and an
 * evas object. With that EPhysics will be able to update evas object
 * position and rotation automatically.
 *
 * This association should be 1:1. You can have physics bodies without evas
 * objects, but you can't have more than an evas object directly associated
 * to this body. If you want more, you can use
 * @ref ephysics_body_event_callback_add() to register a callback that
 * will update the other evas objects. This function can be used to disable
 * updates of associated evas objects, or complement updates, like changing
 * evas objects properties under certain conditions of position or rotation.
 *
 * If it's required to associate evas object to specific faces of the body,
 * function @ref ephysics_body_face_evas_object_set() could be used.
 *
 * @param body The body to associate to an evas object.
 * @param evas_obj The evas object that will be associated to this @p body.
 * @param use_obj_pos If @c EINA_TRUE it will set the physics body position
 * to match evas object position taking world rate on consideration.
 *
 * @see ephysics_body_box_add().
 * @see ephysics_body_soft_box_add().
 * @see ephysics_body_cylinder_add().
 * @see ephysics_body_soft_cylinder_add().
 * @see ephysics_body_evas_object_unset().
 * @see ephysics_world_rate_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_evas_object_set(EPhysics_Body *body, Evas_Object *evas_obj, Eina_Bool use_obj_pos);

/**
 * @brief
 * Unset the evas object associated to a physics body.
 *
 * @param body The body to unset an evas object from.
 * @return The associated evas object, or @c NULL if no object is associated
 * or on error.
 *
 * @see ephysics_body_evas_object_set() for more details.
 *
 * @ingroup EPhysics_Body
 */
EAPI Evas_Object *ephysics_body_evas_object_unset(EPhysics_Body *body);

/**
 * @brief
 * Get the evas object associated to a physics body.
 *
 * @param body The body to get an evas object from.
 * @return The associated evas object, or @c NULL if no object is associated
 * or on error.
 *
 * @see ephysics_body_evas_object_set() for more details.
 *
 * @ingroup EPhysics_Body
 */
EAPI Evas_Object *ephysics_body_evas_object_get(const EPhysics_Body *body);

/**
 * @brief
 * Set an evas object to a physics body face.
 *
 * It will create a direct association between a specific face of the physics
 * body and an evas object.
 * With that EPhysics will be able to update evas object
 * position and rotation automatically.
 *
 * If it's required to associate only one evas object to this body, a more
 * generic function @see ephysics_body_evas_object_set() can be used.
 *
 * @param body The body to associate to an evas object.
 * @param face The specific face of @p body where the evas object will be
 * placed.
 * @param evas_obj The evas object that will be associated to this @p body.
 * @param use_obj_pos If @c EINA_TRUE it will set the physics body position
 * to match evas object position taking world rate on consideration.
 *
 * @see ephysics_body_face_evas_object_unset().
 * @see ephysics_body_face_evas_object_get().
 * @see ephysics_body_evas_object_set().
 * @see ephysics_world_rate_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_face_evas_object_set(EPhysics_Body *body, EPhysics_Body_Face face, Evas_Object *evas_obj, Eina_Bool use_obj_pos);

/**
 * @brief
 * Get the evas object associated to a physics body face.
 *
 * @param body The body to get an evas object from.
 * @param face The specific face of @p body where the evas object was placed.
 * @return The associated evas object, or @c NULL if no object is associated
 * or on error.
 *
 * @see ephysics_body_face_evas_object_set() for more details.
 *
 * @ingroup EPhysics_Body
 */
EAPI Evas_Object *ephysics_body_face_evas_object_get(const EPhysics_Body *body, EPhysics_Body_Face face);

/**
 * @brief
 * Unset the evas object associated to a physics body face.
 *
 * @param body The body to unset an evas object from.
 * @param face The specific face of @p body where the evas object was placed.
 * @return The associated evas object, or @c NULL if no object is associated
 * or on error.
 *
 * @see ephysics_body_face_evas_object_set() for more details.
 *
 * @ingroup EPhysics_Body
 */
EAPI Evas_Object *ephysics_body_face_evas_object_unset(EPhysics_Body *body, EPhysics_Body_Face face);

/**
 * @brief
 * Set physics body size.
 *
 * By default cylinders have diameter equal to 1 meter * rate, boxes have
 * dimensions 1 meter * rate on all the axes.
 *
 * There are three direct ways of modifying it's size:
 * @li With @ref ephysics_body_resize();
 * @li With @ref ephysics_body_geometry_set();
 * @li When associating an evas object with
 * @ref ephysics_body_evas_object_set().
 *
 * @note The unit used for size is Evas coordinates.
 *
 * @param body The body to be resized.
 * @param w The body width, in pixels.
 * @param h The body height, in pixels.
 * @param d The body depth, in pixels.
 *
 * @see ephysics_body_geometry_get().
 * @see ephysics_body_geometry_set().
 * @see ephysics_body_move().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_resize(EPhysics_Body *body, Evas_Coord w, Evas_Coord h, Evas_Coord d);

/**
 * @brief
 * Set physics body position.
 *
 * All the physics bodies are created centered on origin (0, 0, 0).
 *
 * There are three direct ways of modifying this position:
 * @li With @ref ephysics_body_move();
 * @li With @ref ephysics_body_geometry_set();
 * @li When associating an evas object with
 * @ref ephysics_body_evas_object_set().
 *
 * When the world is simulated forces will be applied on objects
 * with mass and position will be modified too.
 *
 * @note The unit used for position is Evas coordinates.
 *
 * @param body The body to be positioned.
 * @param x The position on axis x, in pixels.
 * @param y The position on axis y, in pixels.
 * @param z The position on axis z, in pixels.
 *
 * @see ephysics_body_geometry_get().
 * @see ephysics_body_geometry_set().
 * @see ephysics_body_resize().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_move(EPhysics_Body *body, Evas_Coord x, Evas_Coord y, Evas_Coord z);

/**
 * @brief
 * Set physics body geometry.
 *
 * All the physics bodies are created centered on origin (0, 0) and with
 * canonical dimensions. Cylinder have diameter 1, boxes have dimensions 1
 * on all the axes.
 *
 * There are four direct ways of modifying this geometry:
 * @li With @ref ephysics_body_geometry_set();
 * @li With @ref ephysics_body_move();
 * @li With @ref ephysics_body_resize();
 * @li When associating an evas object with
 * @ref ephysics_body_evas_object_set().
 *
 * If you just need to move the body, no changes are required to it's size,
 * use @ref ephysics_body_move(). If you just need to modify the size of
 * @p body use @ref ephysics_body_resize().
 *
 * When the world is simulated forces will be applied on objects
 * with mass and position will be modified too.
 *
 * @note The unit used for geometry is Evas coordinates.
 *
 * @param body The body to be modified.
 * @param x The position on axis x, in pixels.
 * @param y The position on axis y, in pixels.
 * @param z The position on axis z, in pixels.
 * @param w The body width, in pixels.
 * @param h The body height, in pixels.
 * @param d The body depth, in pixels.
 *
 * @see ephysics_body_geometry_get().
 * @see ephysics_body_move().
 * @see ephysics_body_resize().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_geometry_set(EPhysics_Body *body, Evas_Coord x, Evas_Coord y, Evas_Coord z, Evas_Coord w, Evas_Coord h, Evas_Coord d);

/**
 * @brief
 * Get physics body position.
 *
 * @param body The physics body.
 * @param x The position on axis x, in pixels.
 * @param y The position on axis y, in pixels.
 * @param z The position on axis z, in pixels.
 * @param w The body width, in pixels.
 * @param h The body height, in pixels.
 * @param d The body depth, in pixels.
 *
 * @see ephysics_body_geometry_set() for more details.
 * @see ephysics_body_move().
 * @see ephysics_body_resize().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_geometry_get(const EPhysics_Body *body, Evas_Coord *x, Evas_Coord *y, Evas_Coord *z, Evas_Coord *w, Evas_Coord *h, Evas_Coord *d);

/**
 * @brief
 * Set body's mass.
 *
 * It will set inertial mass of the body. It is a quantitative measure of
 * an object's resistance to the change of its speed. It's required to apply
 * more force on objects with more mass to increase its speed.
 *
 * If mass is set to 0 the body will have infinite mass, so it will be
 * immovable, static. @ref EPHYSICS_BODY_MASS_STATIC can be used too.
 *
 * Negative mass is not allowed.
 *
 * By default, a body is created with 1 kg.
 *
 * @note The unit used for mass is kilograms.
 *
 * @param body The body to has its mass set.
 * @param mass The @p body's mass, in kilograms.
 *
 * @see ephysics_body_mass_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_mass_set(EPhysics_Body *body, double mass);

/**
 * @brief
 * Get body's mass.
 *
 * It will get inertial mass of the body.
 *
 * @param body The physics body.
 * @return the @p body mass, in kilograms.
 *
 * @see ephysics_body_mass_set() for details.
 *
 * @ingroup EPhysics_Body
 */
EAPI double ephysics_body_mass_get(const EPhysics_Body *body);

/**
 * @brief
 * Set body's linear velocity on x, y and z axes.
 *
 * @param body The physics body.
 * @param x The linear velocity on axis x.
 * @param y The linear velocity on axis y.
 * @param z The linear velocity on axis z.
 *
 * @note EPhysics unit for linear velocity is Evas coordinates per second.
 *
 * @see ephysics_body_linear_velocity_get().
 * @see ephysics_body_angular_velocity_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_linear_velocity_set(EPhysics_Body *body, double x, double y, double z);

/**
 * @brief
 * Get body's linear velocity on x, y and z axes.
 *
 * @param body The physics body.
 * @param x The linear velocity on axis x.
 * @param y The linear velocity on axis y.
 * @param z The linear velocity on axis z.
 *
 * @note EPhysics unit for linear velocity is Evas coordinates per second.
 * @note For cloth bodies the returned value is a velocity average of nodes
 * velocities.
 *
 * @see ephysics_body_linear_velocity_set().
 * @see ephysics_body_angular_velocity_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_linear_velocity_get(const EPhysics_Body *body, double *x, double *y, double *z);

/**
 * @brief
 * Set body's angular velocity on x, y and z axes.
 *
 * @param body The physics body.
 * @param x The angular velocity on axis x.
 * @param y The angular velocity on axis y.
 * @param z The angular velocity on axis z.
 *
 * @note EPhysics unit for angular velocity is degrees per second.
 *
 * @see ephysics_body_angular_velocity_get().
 * @see ephysics_body_linear_velocity_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_angular_velocity_set(EPhysics_Body *body, double x, double y, double z);

/**
 * @brief
 * Get body's angular velocity on x, y and z axes.
 *
 * @param body The physics body.
 * @param x The angular velocity on axis x.
 * @param y The angular velocity on axis y.
 * @param z The angular velocity on axis z.
 *
 * @note EPhysics unit for angular velocity is degrees per second.
 *
 * @see ephysics_body_angular_velocity_set().
 * @see ephysics_body_linear_velocity_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_angular_velocity_get(const EPhysics_Body *body, double *x, double *y, double *z);

/**
 * @brief
 * Set the linear and angular sleeping threshold.
 *
 * These factors are used to determine whenever a rigid body is supposed to
 * increment the sleeping time.
 *
 * After every tick the sleeping time is incremented, if the body's linear and
 * angular speed is less than the respective thresholds the sleeping time is
 * incremented by the current time step (delta time).
 *
 * After reaching the max sleeping time the body is marked to sleep, that means
 * the rigid body is to be deactivated.
 *
 * @note The expected value to be informed as @p linear_threshold is
 * the body's speed. It is measured in Evas coordinates per second.
 *
 * @note The expected angular velocity to be informed as @p angular_threshold
 * is measured in degrees per second.
 *
 * @param body The body to be set.
 * @param linear_threshold The linear sleeping threshold factor, default value
 * is 24.
 * @param angular_threshold The angular sleeping threshold factor, default value
 * is 57.29 (1 rad).
 *
 * @see ephysics_body_sleeping_threshold_get().
 * @see ephysics_world_max_sleeping_time_set() for sleeping time details.
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_sleeping_threshold_set(EPhysics_Body *body, double linear_threshold, double angular_threshold);

/**
 * @brief
 * Get the linear sleeping threshold.
 *
 * @note The linear sleeping threshold is measured in Evas coordinates per
 * second and the angular sleeping threshold is measured in degrees per second.
 *
 * @param body The body to get the linear sleeping threshold from.
 * @param linear_threshold The linear sleeping threshold factor.
 * @param angular_threshold The angular sleeping threshold factor.
 *
 * @see ephysics_body_sleeping_threshold_set() for more details.
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_sleeping_threshold_get(const EPhysics_Body *body, double *linear_threshold, double *angular_threshold);

/**
 * @brief
 * Stop angular and linear body movement.
 *
 * It's equivalent to set linear velocity to 0 on both axis and
 * angular velocity to 0 as well.
 *
 * It's a momentary situation. If it receives impulse, directly or
 * by collision, if gravity acts over this body,
 * it will stop but it will accelerate again.
 *
 * @param body The physics body.
 *
 * @see ephysics_body_angular_velocity_set().
 * @see ephysics_body_linear_velocity_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_stop(EPhysics_Body *body);

/**
 * @brief
 * Set the angular and linear damping values.
 *
 * Damping(linear and angular) values are applied to body's linear and angular
 * velocity.
 *
 * By applying a bodies damping factor the user will face a velocity reduction,
 * with a force applied to it - like air resistance. The force is applied to
 * slow it down. Different factors can be applied to angular and linear
 * velocity to fine tune translation and rotation.
 *
 * The damping is a force synchronous with the velocity of the object but in
 * opposite direction.
 *
 * Damping is specified as a value between 0 and 1, which is the proportion of
 * velocity lost per second. If specified damping value - either for angular or
 * linear - is greater or equal to 1, velocities are nulled(that means, will
 * become 0 on every axis), resulting on a frozen body.
 *
 * Default linear damping is set to 0. The same is true for angular damping
 * factor.
 *
 * @param body The physics body.
 * @param linear_damping The linear damping factor to apply on @p body.
 * @param angular_damping The angular damping factor to apply on @p body.
 *
 * @see ephysics_body_damping_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_damping_set(EPhysics_Body *body, double linear_damping, double angular_damping);

/**
 * @brief
 * Get the angular and linear damping values.
 *
 * Damping(linear and angular) values are applied to body's linear and angular
 * velocity.
 *
 * @param body The physics body.
 * @param linear_damping The linear damping factor applied over @p body.
 * @param angular_damping The angular damping factor applied over @p body.
 *
 * @see ephysics_body_damping_set() for details.
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_damping_get(const EPhysics_Body *body, double *linear_damping, double *angular_damping);

/**
 * @brief
 * Add a @p body to a given collision group.
 *
 * After calling this function the body is said to be added to collision @p
 * group.
 *
 * If not added to any group the body will collide against any other body.
 * Otherwise this body will collide only against those in the same groups.
 *
 * If @p body was already part of @p group, nothing will happen.
 *
 * @param body The body to be added to @p group.
 * @param group The group the @p body will belong to.
 * @return @c EINA_TRUE if body is added to group, or @c EINA_FALSE on error.
 *
 * @see ephysics_body_collision_group_del()
 * @see ephysics_body_collision_group_list_get()
 * @ingroup EPhysics_Body
 */
EAPI Eina_Bool ephysics_body_collision_group_add(EPhysics_Body *body, const char *group);

/**
 * @brief
 * Removes @p body from collision @p group.
 *
 * This @p body will not belong to @p group any more and the collisions filter
 * must take that on account.
 *
 * If @p body wasn't part of @p group before, nothing will happen.
 *
 * @param body The body to be removed from @p group.
 * @param group The group @p body must be removed from.
 * @return @c EINA_TRUE if body is removed from group, or @c EINA_FALSE on
 * error.
 *
 * @see ephysics_body_collision_group_add()
 * @ingroup EPhysics_Body
 */
EAPI Eina_Bool ephysics_body_collision_group_del(EPhysics_Body *body, const char *group);

/**
 * @brief
 * Get the collision group list of @p body.
 *
 * @param body The body of interest.
 * @return The collision group list of @p body, NULL on failure or case no
 * group has been added to @p body.
 *
 * @warning The collision group list is an EPhysics internal data structure and
 * should @b never be modified by its callers.
 *
 * @see ephysics_body_collision_group_add()
 * @ingroup EPhysics_Body
 */
EAPI const Eina_List *ephysics_body_collision_group_list_get(const EPhysics_Body *body);

/**
 * @brief
 * Update the evas object associated to the body.
 *
 * This function should be called to update position and rotation of
 * the evas object associated to the body with
 * @ref ephysics_body_evas_object_set().
 * It will take rate between pixels and meters set with
 * @ref ephysics_world_rate_set() in account.
 *
 * If an update callback wasn't set with
 * @ref ephysics_body_event_callback_add(), this function will be executed
 * after each physics simulation tick. If a callback was set, it won't be
 * called automatically. So inside this callback it could be called, or
 * a customized update could be implemented.
 *
 * @see ephysics_body_event_callback_add() for more details.
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_evas_object_update(EPhysics_Body *body);

/**
 * @brief
 * Register a callback to a type of physics body event.
 *
 * The registered callback will receives the body and extra user data that
 * can be passed. From body it's possible to get the world it belongs to
 * with @ref ephysics_body_world_get(), the rate between pixels and meters
 * with @ref ephysics_world_rate_get() and the associated evas object with
 * @ref ephysics_body_evas_object_get().
 *
 * So it's enough to do customized updates or fix pointers in your program.
 *
 * Regarding EPHYSICS_CALLBACK_BODY_UPDATE:
 *
 * This update event happens after each physics world tick. Its main use
 * could be updating the evas object associated to a physics body.
 *
 * If no callback is registered, the evas object associated to physics body
 * will be automatically moved and rotated, taking rate between meters and
 * pixels on account. This rate is set by @ref ephysics_world_rate_set().
 *
 * If callbacks are registered, these function will be called and will
 * be responsible for updating the evas object. If the default update
 * is wanted, function @ref ephysics_body_evas_object_update() can be called
 * inside the callback. So you could make changes before and after
 * the evas object is updated.
 *
 * A callback could be something like this:
 * @code
 *   static void
 *   _update_cb(void *data, EPhysics_Body *body, void *event_info)
 *   {
 *     // Something you want to do before updating the evas object
 *     ephysics_body_evas_object_update(body);
 *     // Something to be done after the update, like checking the new position
 *     // of the evas object to change a property.
 *   }
 *
 *  ephysics_body_event_callback_add(body, EPHYSICS_CALLBACK_BODY_UPDATE,
 *                                   _update_cb, NULL);
 * @endcode
 *
 * Update callbacks receives evas object set to body as event_info argument.
 *
 * What follows is a list of details about each callback type:
 *
 * - #EPHYSICS_CALLBACK_BODY_UPDATE: Called after every physics iteration. @p
 *   body points to the EPhysics_Body itself and @p event_info points to the
 *   evas object associated to the body.
 *
 * - #EPHYSICS_CALLBACK_BODY_COLLISION: Called just after the collision has
 *   been actually processed by the physics engine. The body involved in the
 *   collision is passed as @p body argument. @p event_info is a pointer to
 *   @ref EPhysics_Body_Collision - note, this structure(@p event_info) is
 *   discarded/freed right after callback returns.
 *
 * - #EPHYSICS_CALLBACK_BODY_DEL: Called when a body deletion has been issued
 *   and just before the deletion actually happens. @p body points to the body
 *   being deleted and @p event_info is a pointer to the evas object
 *   associated to it.
 *
 * - #EPHYSICS_CALLBACK_BODY_STOPPED: Called when a body is found to be
 *   stopped. @p body points to the body of interest and @p event_info is a
 *   pointer to the evas object associated to it.
 *
 * @param body The physics body.
 * @param type Type of callback to be listened by @p func.
 * @param func Callback function that will be called when event occurs.
 * @param data User data that will be passed to callback function. It won't
 * be used by ephysics in any way.
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_event_callback_add(EPhysics_Body *body, EPhysics_Callback_Body_Type type, EPhysics_Body_Event_Cb func, const void *data);

/**
 * @brief
 * Unregister an ephysics body event callback.
 *
 * A previously added callback that match @p body, @p type and @p func
 * will be deleted.
 *
 * @param body The physics body.
 * @param type The type of callback to be unregistered.
 * @param func The callback function to be unregistered.
 * @return The user data passed when the callback was registered, or @c NULL
 * on error.
 *
 * @see ephysics_body_event_callback_add() for details.
 * @see ephysics_body_event_callback_del_full() if you need to match data
 * pointer.
 *
 * @ingroup EPhysics_Body
 */
EAPI void *ephysics_body_event_callback_del(EPhysics_Body *body, EPhysics_Callback_Body_Type type, EPhysics_Body_Event_Cb func);

/**
 * @brief
 * Unregister an ephysics body event callback matching data pointer.
 *
 * A previously added callback that match @p body, @p type, @p func
 * and @p data will be deleted.
 *
 * @param body The physics body.
 * @param type The type of callback to be unregistered.
 * @param func The callback function to be unregistered.
 * @param data The data pointer that was passed to the callback.
 * @return The user data passed when the callback was registered, or @c NULL
 * on error.
 *
 * @see ephysics_body_event_callback_add() for details.
 * @see ephysics_body_event_callback_del() if you don't need to match data
 * pointer.
 *
 * @ingroup EPhysics_Body
 */
EAPI void *ephysics_body_event_callback_del_full(EPhysics_Body *body, EPhysics_Callback_Body_Type type, EPhysics_Body_Event_Cb func, void *data);

/**
 * @brief
 * Get the position(x, y) of a body's collision.
 *
 * Given a body collision data, fills @p x and @p y pointers with the position
 * where the collision occurred.
 *
 * @param collision The body collision data of interest.
 * @param x The x coordinate of collision point, in pixels.
 * @param y The y coordinate of collision point, in pixels.
 * @param z The z coordinate of collision point, in pixels.
 *
 * @see EPHYSICS_CALLBACK_BODY_COLLISION and @ref
 * ephysics_body_event_callback_add() for collision callback.
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_collision_position_get(const EPhysics_Body_Collision *collision, Evas_Coord *x, Evas_Coord *y, Evas_Coord *z);

/**
 * @brief
 * Get the body's collision contact body.
 *
 * Given a body collision data returns the contact body which a collision
 * occurred against.
 *
 * @param collision The body collision of interest.
 * @return The contact body of @p collision.
 *
 * @see EPHYSICS_CALLBACK_BODY_COLLISION and @ref
 * ephysics_body_event_callback_add() for collision callback.
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body *ephysics_body_collision_contact_body_get(const EPhysics_Body_Collision *collision);

/**
 * @brief
 * Set body's coefficient of restitution.
 *
 * The coefficient of restitution is proporcion between speed after and
 * before a collision:
 * COR = relative speed after collision / relative speed before collision
 *
 * The body COR is the coefficient of restitution with respect to a perfectly
 * rigid and elastic object. Bodies will collide between them with different
 * behaviors depending on COR:
 * @li they will elastically collide for COR == 1;
 * @li they will inelastically collide for 0 < COR < 1;
 * @li they will completelly stop (no bouncing at all) for COR == 0.
 *
 * By default restitution coefficient of each body is 0.
 *
 * EPhysics has some pre-defined restitution coefficients for materials:
 * @li @ref EPHYSICS_BODY_RESTITUTION_CONCRETE
 * @li @ref EPHYSICS_BODY_RESTITUTION_IRON
 * @li @ref EPHYSICS_BODY_RESTITUTION_PLASTIC
 * @li @ref EPHYSICS_BODY_RESTITUTION_POLYSTYRENE
 * @li @ref EPHYSICS_BODY_RESTITUTION_RUBBER
 * @li @ref EPHYSICS_BODY_RESTITUTION_WOOD
 *
 * @param body The body to has its restitution coefficient set.
 * @param restitution The new @p body's restitution coefficient.
 *
 * @see ephysics_body_restitution_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_restitution_set(EPhysics_Body *body, double restitution);

/**
 * @brief
 * Get body's restitution.
 *
 * @param body The physics body.
 * @return the @p body's restitution value.
 *
 * @see ephysics_body_restitution_set() for details.
 *
 * @ingroup EPhysics_Body
 */
EAPI double ephysics_body_restitution_get(const EPhysics_Body *body);

/**
 * @brief
 * Set body's friction.
 *
 * Friction is used to make objects slide along each other realistically.
 *
 * The friction parameter is usually set between 0 and 1, but can be any
 * non-negative value. A friction value of 0 turns off friction and a value
 * of 1 makes the friction strong.
 *
 * By default friction value is 0.5 and simulation results will be better
 * when friction in non-zero.
 *
 * EPhysics has some pre-defined friction coefficients for materials:
 * @li @ref EPHYSICS_BODY_FRICTION_CONCRETE
 * @li @ref EPHYSICS_BODY_FRICTION_IRON
 * @li @ref EPHYSICS_BODY_FRICTION_PLASTIC
 * @li @ref EPHYSICS_BODY_FRICTION_POLYSTYRENE
 * @li @ref EPHYSICS_BODY_FRICTION_RUBBER
 * @li @ref EPHYSICS_BODY_FRICTION_WOOD
 *
 * @param body The body to has its friction set.
 * @param friction The new @p body's friction value.
 *
 * @see ephysics_body_friction_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_friction_set(EPhysics_Body *body, double friction);

/**
 * @brief
 * Get body's friction.
 *
 * @param body The physics body.
 * @return the @p body's friction value.
 *
 * @see ephysics_body_friction_set() for details.
 *
 * @ingroup EPhysics_Body
 */
EAPI double ephysics_body_friction_get(const EPhysics_Body *body);

/**
 * @brief
 * Apply an impulse on the center of a body.
 *
 * The impulse is equal to the change of momentum of the body.
 *
 * Impulse is the product of the force over the time this force is applied.
 * In ephysics case, it would be the time of a tick, so it behaves just
 * summing current linear velocity to impulse per mass.
 *
 * Example:
 * A body of 2kg of mass has an initial velocity of 30 p/s.
 * After a impulse of 30 kg * p / s in the same direction is applied,
 * the velocity will be * 45 p/s.
 *
 *    (0, 30, 0) + (0, 300, 0) / 2 = (0, 30, 0) + (0, 15, 0) = (0, 45, 0)
 *
 * When a impulse is applied over a body, it will has its velocity changed.
 * This impulse will be applied on body's center, so it won't implies in
 * rotating the body. For that is possible to apply a torque impulse with
 * @ref ephysics_body_torque_impulse_apply().
 *
 * @note Impulse is measured in kg * p / s.
 *
 * @param body The physics body that will receive the impulse.
 * @param x The axis x component of impulse.
 * @param y The axis y component of impulse.
 * @param z The axis z component of impulse.
 *
 * @see ephysics_body_torque_impulse_apply().
 * @see ephysics_body_impulse_apply().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_central_impulse_apply(EPhysics_Body *body, double x, double y, double z);

/**
 * @brief
 * Apply a torque impulse over a body.
 *
 * An impulse will be applied over the body to make it rotate.
 * Impulse is the product of the force over the time this force is applied.
 * In ephysics case, it would be the time of a tick, so it behaves just
 * summing current angular velocity to the result of a calculation involving
 * torque impulse and body's inertia.
 *
 * @param body The physics body that will receive the impulse.
 * @param pitch Impulse to rotate body around X axis (rotate on y - z plane).
 * Negative values will impulse body on counter clockwise rotation.
 * @param yaw Impulse to rotate body around Y axis (rotate on x - z plane).
 * Negative values will impulse body on counter clockwise rotation.
 * @param roll Impulse to rotate body around Z axis (rotate on x - y plane).
 * Negative values will impulse body on counter clockwise rotation.
 *
 * @see ephysics_body_central_impulse_apply().
 * @see ephysics_body_impulse_apply().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_torque_impulse_apply(EPhysics_Body *body, double pitch, double yaw, double roll);

/**
 * @brief
 * Apply an impulse over a body.
 *
 * An impulse will be applied over the body to make it move and rotate.
 *
 * Impulse is the product of the force over the time this force is applied.
 * It can be applied in the center of the body, avoiding rotating it,
 * with @ref ephysics_body_central_impulse_apply(), it can be applied only
 * to make a body rotate, with @ref ephysics_body_torque_impulse_apply(),
 * or can be used to lead to both behaviors with
 * @ref ephysics_body_impulse_apply().
 *
 * It will result in a central impulse with impulse (@p x, @p y, @p z) and a
 * torque impulse that will be calculated as a cross product on impulse
 * and relative position.
 *
 * @param body The physics body that will receive the impulse.
 * @param x The axis x component of impulse.
 * @param y The axis y component of impulse.
 * @param z The axis z component of impulse.
 * @param pos_x The axis x component of the relative position to apply impulse.
 * @param pos_y The axis y component of the relative position to apply impulse.
 * @param pos_z The axis z component of the relative position to apply impulse.
 *
 * @note Impulse is measured in kg * p / s and position in pixels
 * (Evas coordinates).
 *
 * @see ephysics_body_central_impulse_apply().
 * @see ephysics_body_torque_impulse_apply().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_impulse_apply(EPhysics_Body *body, double x, double y, double z, Evas_Coord pos_x, Evas_Coord pos_y, Evas_Coord pos_z);

/**
 * @brief
 * Enable or disable body's rotation on z axis.
 *
 * Enabled by default for z axis, so the body only will rotate on x-y plane.
 *
 * @param body The physics body.
 * @param enable_x If @c EINA_TRUE allow rotation on x axis (y-z plane),
 * if @c EINA_FALSE disallow it.
 * @param enable_y If @c EINA_TRUE allow rotation on y axis (x-z plane),
 *if @c EINA_FALSE disallow it.
 * @param enable_z If @c EINA_TRUE allow rotation on z axis (x-y plane),
 * if @c EINA_FALSE disallow it.
 *
 * @see ephysics_body_angular_movement_enable_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_angular_movement_enable_set(EPhysics_Body *body, Eina_Bool enable_x, Eina_Bool enable_y, Eina_Bool enable_z);

/**
 * @brief
 * Return body's rotation on z axis state.
 *
 * @param body The physics body.
 * @param enable_x @c EINA_TRUE if rotation on x axis (y-z plane) is allowed, or
 * @c EINA_FALSE if it's not.
 * @param enable_y @c EINA_TRUE if rotation on y axis (x-z plane) is allowed, or
 * @c EINA_FALSE if it's not.
 * @param enable_z @c EINA_TRUE if rotation on z axis (x-y plane) is allowed, or
 * @c EINA_FALSE if it's not.
 *
 * @see ephysics_body_angular_movement_enable_set() for more details.
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_angular_movement_enable_get(const EPhysics_Body *body, Eina_Bool *enable_x, Eina_Bool *enable_y, Eina_Bool *enable_z);

/**
 * @brief
 * Enable or disable body's movement on x, y and z axes.
 *
 * Enabled by default on x and y axes, disabled on z axis.
 *
 * @param body The physics body.
 * @param enable_x If @c EINA_TRUE allow movement on x axis, if @c EINA_FALSE
 * disallow it.
 * @param enable_y If @c EINA_TRUE allow movement on y axis, if @c EINA_FALSE
 * disallow it.
 * @param enable_z If @c EINA_TRUE allow movement on z axis, if @c EINA_FALSE
 * disallow it.
 *
 * @see ephysics_body_linear_movement_enable_get().
 * @see ephysics_body_angular_movement_enable_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_linear_movement_enable_set(EPhysics_Body *body, Eina_Bool enable_x, Eina_Bool enable_y, Eina_Bool enable_z);

/**
 * @brief
 * Get body's movement on x, y and z axes behavior.
 *
 * @param body The physics body.
 * @param enable_x @c EINA_TRUE if movement on x axis is allowed, or
 * @c EINA_FALSE if it's not.
 * @param enable_y @c EINA_TRUE if movement on y axis is allowed, or
 * @c EINA_FALSE if it's not.
 * @param enable_z @c EINA_TRUE if movement on z axis is allowed, or
 * @c EINA_FALSE if it's not.
 *
 * @see ephysics_body_linear_movement_enable_set().
 * @see ephysics_body_angular_movement_enable_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_linear_movement_enable_get(const EPhysics_Body *body, Eina_Bool *enable_x, Eina_Bool *enable_y, Eina_Bool *enable_z);

/**
 * @brief
 * Get body's rotation quaternion.
 *
 * By default rotation is 0 degree on all axes (1, 0, 0, 0).
 *
 * @param body The physics body.
 * @param rotation Quaternion used to store the result. If it's @c NULL, a new
 * quaternion will be allocated (and should be freed after usage).
 * @return A quaternion or @c NULL on error.
 *
 * @see ephysics_body_rotation_set()
 * @see ephysics_quaternion_get()
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Quaternion *ephysics_body_rotation_get(const EPhysics_Body *body, EPhysics_Quaternion *rotation);

/**
 * @brief
 * Set body's rotation.
 *
 * By default rotation is 0 degrees on all axes.
 *
 * @param body The physics body.
 * @param quat Quaternion representing the rotation.
 *
 * @see ephysics_body_rotation_get()
 * @see ephysics_quaternion_new()
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_rotation_set(EPhysics_Body *body, EPhysics_Quaternion *quat);

/**
 * @brief
 * Set data to @p body.
 *
 * If a previous data was set, it's reference will be lost and body
 * will point to the new data.
 *
 * It can be useful when you need to store a structure per body. For example,
 * some values that must to be updated when a collision occurs between two
 * bodies.
 *
 * @note EPhysics won't handle this data, it won't be used in any way
 * by the library. If it need to be freed when the body is deleted, a
 * callback for @ref EPHYSICS_CALLBACK_BODY_DEL can be added and
 * data should be explicity freed.
 *
 * @param body The physics body.
 * @param data The data to be set.
 *
 * @see ephysics_body_data_get()
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_data_set(EPhysics_Body *body, void *data);

/**
 * @brief
 * Return data previously set to body.
 *
 * @param body The physics body.
 * @return The data set or @c NULL on error.
 *
 * @see ephysics_body_data_get() for more details
 *
 * @ingroup EPhysics_Body
 */
EAPI void *ephysics_body_data_get(const EPhysics_Body *body);

/**
 * @brief
 * Apply a force on the center of a body.
 *
 * Applying a force to a body will lead it to change its velocity.
 *
 * Force is the product of mass and acceleration. So, keeping the mass
 * fixed, when force is applied acceleration will change, and consequently,
 * velocity will gradually be changes.
 *
 * Force = mass * acceleration
 *
 * Final velocity = initial velocity + acceleration * time
 *
 * While a force is applied, it will be acting over a body. It can be canceled
 * by applying an inverse force, or just calling
 * @ref ephysics_body_forces_clear().
 *
 * This force will be applied on body's center, so it won't implies in
 * changing angular acceleration. For that, it is possible to apply a torque
 * with @ref ephysics_body_torque_apply().
 *
 * If the force shouldn't be applied on body's center, it can be applied on
 * a relative point with @ref ephysics_body_force_apply().
 *
 * @note Force is measured in kg * p / s / s.
 *
 * @param body The physics body which over the force will be applied.
 * @param x The axis x component of force.
 * @param y The axis y component of force.
 * @param z The axis z component of force.
 *
 * @see ephysics_body_torque_apply().
 * @see ephysics_body_force_apply().
 * @see ephysics_body_forces_get().
 * @see ephysics_body_torques_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_central_force_apply(EPhysics_Body *body, double x, double y, double z);

/**
 * @brief
 * Apply a torque over a body.
 *
 * A torque will be applied over the @p body to change the angular acceleration
 * of this body. It will leads to a change on angular velocity over time.
 *
 * @param body The physics body that will receive the torque.
 * @param torque_x Torque to change angular acceleration of the body around X
 * axis (rotate on y - z plane).
 * Negative values will accelerate it on counter clockwise rotation.
 * @param torque_y Torque to change angular acceleration of the body around Y
 * axis (rotate on x - z plane).
 * Negative values will accelerate it on counter clockwise rotation.
 * @param torque_z Torque to change angular acceleration of the body around Z
 * axis (rotate on x - y plane).
 * Negative values will accelerate it on counter clockwise rotation.
 *
 * @see ephysics_body_central_force_apply().
 * @see ephysics_body_force_apply().
 * @see ephysics_body_forces_get().
 * @see ephysics_body_torques_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_torque_apply(EPhysics_Body *body, double torque_x, double torque_y, double torque_z);

/**
 * @brief
 * Apply a force over a body.
 *
 * A force will be applied over the body to change it's linear and angular
 * accelerations.
 *
 * It can be applied in the center of the body, avoiding affecting angular
 * acceleration, with @ref ephysics_body_central_force_apply(),
 * it can be applied only to change angular acceleration, with
 * @ref ephysics_body_torque_apply(), or can be used to lead to both
 * behaviors with @ref ephysics_body_force_apply().
 *
 * It will result in a central force with force (@p x, @p y, @p z) and a
 * torque that will be calculated as a cross product on force
 * and relative position.
 *
 * @param body The physics body that will receive the impulse.
 * @param x The axis x component of force.
 * @param y The axis y component of force.
 * @param z The axis z component of force.
 * @param pos_x The axis x component of the relative position to apply force.
 * @param pos_y The axis y component of the relative position to apply force.
 * @param pos_z The axis z component of the relative position to apply force.
 *
 * @note Force is measured in kg * p / s / s and position in p (pixels, or
 * Evas coordinates).
 *
 * @see ephysics_body_central_force_apply().
 * @see ephysics_body_torque_apply().
 * @see ephysics_body_forces_get().
 * @see ephysics_body_torques_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_force_apply(EPhysics_Body *body, double x, double y, double z, Evas_Coord pos_x, Evas_Coord pos_y, Evas_Coord pos_z);

/**
 * @brief
 * Get physics body forces.
 *
 * Get all the forces applied over a body, including gravity.
 * Damping is not considered.
 *
 * @param body The physics body.
 * @param x The axis x component of total force.
 * @param y The axis y component of total force.
 * @param z The axis z component of total force.
 *
 * @see ephysics_body_force_apply() for more details.
 * @see ephysics_body_central_force_apply().
 * @see ephysics_body_torque_apply().
 * @see ephysics_body_torques_get().
 * @see ephysics_body_forces_clear().
 * @see ephysics_world_gravity_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_forces_get(const EPhysics_Body *body, double *x, double *y, double *z);

/**
 * @brief
 * Get physics body torques.
 *
 * Get all the torques applied over a body.
 * Damping is not considered.
 *
 * @param body The physics body.
 * @param x The torque on x axis.
 * @param y The torque on y axis.
 * @param z The torque on z axis.
 *
 * @see ephysics_body_torque_apply() for more details.
 * @see ephysics_body_force_apply().
 * @see ephysics_body_forces_clear().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_torques_get(const EPhysics_Body *body, double *x, double *y, double *z);

/**
 * @brief
 * Clear all the forces applied to a body.
 *
 * It will remove all the forces previously applied. So linear acceleration
 * and angular acceleration will be set to 0.
 *
 * It won't interfere with world's gravity, the body will continue to be
 * accelerated considering gravity.
 *
 * It won't affect damping.
 *
 * @param body The physics body that will have applied forces set to 0.
 *
 * @see ephysics_body_central_force_apply().
 * @see ephysics_body_torque_apply().
 * @see ephysics_body_force_apply().
 * @see ephysics_body_forces_get().
 * @see ephysics_body_torques_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_forces_clear(EPhysics_Body *body);

/**
 * @brief
 * Get the center of mass of physics body.
 *
 * It returns a value from 0 to 1 representing where is the center of the mass
 * considering the height, width and depth of the body.
 *
 * If a body of width = 30, height = 20 and depth = 20, and has the center of
 * mass at x component = 20, y component = 10 and z = 10, it will return
 * @p x = 0.666, @p y = 0.5 and @p z = 0.5.
 *
 * For primitive shapes, like box and cylinder, the center of mass
 * is (0.5, 0.5, 0.5).
 *
 * This function can be useful when updating evas objects for bodies
 * with custom shapes.
 *
 * @param body The physics body.
 * @param x The axis x component of center of mass.
 * @param y The axis y component of center of mass.
 * @param z The axis z component of center of mass.
 *
 * @see ephysics_body_shape_add().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_center_mass_get(const EPhysics_Body *body, double *x, double *y, double *z);

/**
 * @brief
 * Set body's material density.
 *
 * The density of a material is its mass per unit volume. It will set the
 * body mass considering its volume. While a density is set, resizing
 * a body will always recalculate its mass.
 *
 * When a mass is explicitely set with @ref ephysics_body_mass_set(),
 * the density will be unset.
 *
 * It's useful in cases where a specific material needs to be simulated,
 * so its density can be set and ephysics will calcute the body's mass.
 *
 * By default, no density is set.
 *
 * EPhysics has some pre-defined density values for materials:
 * @li @ref EPHYSICS_BODY_DENSITY_CONCRETE
 * @li @ref EPHYSICS_BODY_DENSITY_IRON
 * @li @ref EPHYSICS_BODY_DENSITY_PLASTIC
 * @li @ref EPHYSICS_BODY_DENSITY_POLYSTYRENE
 * @li @ref EPHYSICS_BODY_DENSITY_RUBBER
 * @li @ref EPHYSICS_BODY_DENSITY_WOOD
 *
 * @note The unit used for density is kilograms / meters ^ 3.
 *
 * @param body The body to has its material density set.
 * @param density The @p body's material density, in kilograms / meters ^ 3.
 *
 * @see ephysics_body_density_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_density_set(EPhysics_Body *body, double density);

/**
 * @brief
 * Get body's material density.
 *
 * @param body The physics body.
 * @return the @p body material's density, in kilograms / meters ^ 3 or 0
 * if no density is set.
 *
 * @see ephysics_body_density_set() for details.
 *
 * @ingroup EPhysics_Body
 */
EAPI double ephysics_body_density_get(const EPhysics_Body *body);

/**
 * @brief
 * Get body's volume.
 *
 * @note The unit of the returned value is meters ^ 3. Not pixels. Useful
 * for calculation with mass and density.
 *
 * @param body The physics body.
 * @return the @p body's volume, in meters ^ 3 or -1 on error.
 *
 * @see ephysics_body_geometry_set().
 * @see ephysics_body_geometry_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI double ephysics_body_volume_get(const EPhysics_Body *body);

/**
 * @brief
 * Set body's material.
 *
 * This function makes properties setting easy. When a material is set to
 * a body, it will update its friction, restitution and density,
 * recalculating its mass.
 *
 * EPhysics support some materials defined by @ref EPhysics_Body_Material.
 *
 * So, for example, if @ref EPHYSICS_BODY_MATERIAL_WOOD is set, it will
 * set body's density to @ref EPHYSICS_BODY_DENSITY_WOOD, restitution
 * to @ref EPHYSICS_BODY_RESTITUTION_WOOD and friction to
 * @ref EPHYSICS_BODY_FRICTION_WOOD.
 *
 * If any of these values are later explicitely set, the material will
 * be set back to @ref EPHYSICS_BODY_MATERIAL_CUSTOM, the default.
 *
 * @param body The body to has its material set.
 * @param material The @p material to be used by the body.
 *
 * @see ephysics_body_material_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_material_set(EPhysics_Body *body, EPhysics_Body_Material material);

/**
 * @brief
 * Get body's material.
 *
 * @param body The physics body.
 * @return the @p material used by the body.
 *
 * @see ephysics_body_material_set() for more details.
 *
 * @ingroup EPhysics_Body
 */
EAPI EPhysics_Body_Material ephysics_body_material_get(const EPhysics_Body *body);

/**
 * @brief
 * Set light effect over body.
 *
 * @param body The physics body.
 * @param enable If @c EINA_TRUE, light will be applied over this @p body,
 * otherwise it won't.
 *
 * It's possible to set the light to apply over all the bodies with
 * @ref ephysics_world_light_all_bodies_set(). This will have priority
 * over body's individual light settings.
 *
 * So, if @p body is set to doesn't be affect by the light, but light
 * is set to be applied over all the bodies, @p body will be displayed
 * with light over it.
 *
 * @see ephysics_body_light_get().
 * @see ephysics_world_point_light_position_set() for more details
 * regarding lighting.
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_light_set(EPhysics_Body *body, Eina_Bool enable);

/**
 * @brief
 * Get light effect over body.
 *
 * @param body The physics body.
 * @return @c EINA_TRUE if light is applied over this @p body or @c EINA_FALSE
 * in the other case, or on error.
 *
 * @note If light is applied over all the bodies it may return @c EINA_FALSE
 * even if it's being affect by lights. This need to be checked with
 * @ref ephysics_world_light_all_bodies_get().
 *
 * @see ephysics_body_light_set() for more details.
 *
 * @ingroup EPhysics_Body
 */
EAPI Eina_Bool ephysics_body_light_get(const EPhysics_Body *body);

/**
 * @brief
 * Set body's evas object to be hidden when it is counter-clockwise.
 *
 * @param body The physics body.
 * @param enable If @c EINA_TRUE, evas object will be hidden,
 * otherwise it will be visible, rotated.
 *
 * An object is said to be facing the user when all its points are placed in
 * a clockwise fashion.
 *
 * @note When back-face culling is enabled, evas object visibility
 * will be handled by @ref ephysics_body_evas_object_update().
 *
 * @see ephysics_body_back_face_culling_get().
 * @see ephysics_body_clockwise_get().
 * @see ephysics_body_evas_object_set().
 *
 * @ingroup EPhysics_Body
 */
EAPI void ephysics_body_back_face_culling_set(EPhysics_Body *body, Eina_Bool enable);

/**
 * @brief
 * Return if body's evas object will be hidden when it is counter-clockwise or
 * not.
 *
 * @param body The physics body.
 * @return @c EINA_TRUE if evas object will be hidden, or @c EINA_FALSE
 * in the other case, or on error.
 *
 * @see ephysics_body_back_face_culling_set() for more details.
 * @see ephysics_body_clockwise_get().
 *
 * @ingroup EPhysics_Body
 */
EAPI Eina_Bool ephysics_body_back_face_culling_get(const EPhysics_Body *body);

/**
 * @brief
 * Get the clockwise state of a body.
 *
 * This determines if the points of the evas object associated to the @p body
 * are clockwise or counter-clockwise. This can be used for "back-face culling". * This is where you hide objects that "face away" from you.
 * In this case objects that are not clockwise.
 *
 * It can be set with @ref ephysics_body_back_face_culling_set(), so EPhysics
 * will handle visibility automatically on evas object update.
 *
 * @note This information only will be updated on
 * ephysics_body_evas_object_update(). So if a custom rendering is being done,
 * this function won't return the current value of the evas object.
 *
 * @param body The physics body.
 * @return @c EINA_TRUE if clockwise, @c EINA_FALSE otherwise or on error.
 *
 * @see ephysics_body_back_face_culling_set() for more details.
 *
 * @ingroup EPhysics_Body
 */
EAPI Eina_Bool ephysics_body_clockwise_get(const EPhysics_Body *body);

/**
 * @}
 */

/**
 * @defgroup EPhysics_Constraint EPhysics Constraint
 * @ingroup EPhysics
 *
 * @{
 *
 * Constraints can be used to limit bodies movements, between bodies or
 * between bodies and the world. Constraints can limit movement angle,
 * translation, or work like a motor.
 *
 * Constraints can be created with @ref ephysics_constraint_linked_add()
 * or @ref ephysics_constraint_add() and removed
 * with @ref ephysics_constraint_del().
 * Can be applied between two bodies or between a body and the world.
 */

typedef struct _EPhysics_Constraint EPhysics_Constraint; /**< Constraint handle, used to limit bodies movements. Created with @ref ephysics_constraint_linked_add() or @ref ephysics_constraint_add() and deleted with @ref ephysics_constraint_del(). */

/**
 * @brief
 * Create a new constraint between 2 bodies(Point to Point constraint).
 *
 * The constraint will join two bodies(@p body1 and @p body2) with angular and
 * linear movements limited by calling ephysics_constraint_linear_limit_set()
 * and ephysics_constraint_angular_limit_set(). Anchors values can be defined
 * with ephysics_constraint_anchor_set().
 *
 * @param body1 The first body to apply the constraint.
 * @param body2 The second body to apply the constraint.
 * @return A new linked(joining 2 bodies) constraint or @c NULL, on errors.
 *
 * @see ephysics_constraint_del().
 *
 * @ingroup EPhysics_Constraint
 */
EAPI EPhysics_Constraint *ephysics_constraint_linked_add(EPhysics_Body *body1, EPhysics_Body *body2);

/**
 * @brief
 * Change the constraints anchors values on both constrained bodies.
 *
 * @note By default the anchors are in the middle of a body, if a body of 20, 20
 * is positioned at (10, 10) then its anchor is set to (20, 20).
 *
 * @note There`s no need to inform @p anchor_b2_x, @p anchor_b2_y and @p
 * anchor_b2_z if the constraint has been created using
 * ephysics_constraint_add().
 *
 * @param constraint The constraint to be set.
 * @param anchor_b1_x The first body X anchor.
 * @param anchor_b1_y The first body Y anchor.
 * @param anchor_b1_z The first body Z anchor.
 * @param anchor_b2_x The second body X anchor.
 * @param anchor_b2_y The second body Y anchor.
 * @param anchor_b2_z The second body Z anchor.
 *
 * @see ephysics_constraint_anchor_get().
 * @see ephysics_constraint_linked_add().
 *
 * @ingroup EPhysics_Constraint
 */
EAPI void ephysics_constraint_anchor_set(EPhysics_Constraint *constraint, Evas_Coord anchor_b1_x, Evas_Coord anchor_b1_y, Evas_Coord anchor_b1_z, Evas_Coord anchor_b2_x, Evas_Coord anchor_b2_y, Evas_Coord anchor_b2_z);

/**
 * @brief
 * Get the constraints anchors values on both constrained bodies.
 *
 * @param constraint The constraint to get anchor values from.
 * @param anchor_b1_x Pointer to an Evas_Coord in which to store the first body
 * X anchor value.
 * @param anchor_b1_y Pointer to an Evas_Coord in which to store the first body
 * Y anchor value.
 * @param anchor_b1_z Pointer to an Evas_Coord in which to store the first body
 * Z anchor value.
 * @param anchor_b2_x Pointer to an Evas_Coord in which to store the second body
 * X anchor value.
 * @param anchor_b2_y Pointer to an Evas_Coord in which to store the second body
 * Y anchor value.
 * @param anchor_b2_z Pointer to an Evas_Coord in which to store the second body
 * Z anchor value.
 *
 * @see ephysics_constraint_anchor_set().
 * @see ephysics_constraint_linked_add().
 *
 * @ingroup EPhysics_Constraint
 */
EAPI void ephysics_constraint_anchor_get(const EPhysics_Constraint *constraint, Evas_Coord *anchor_b1_x, Evas_Coord *anchor_b1_y, Evas_Coord *anchor_b1_z, Evas_Coord *anchor_b2_x, Evas_Coord *anchor_b2_y, Evas_Coord *anchor_b2_z);

/**
 * @brief
 * Create a new constraint.
 *
 * The constraint will limit the linear and angular moving of a body. This simple
 * constraint is designated to constraint a single body.
 *
 * @param body The body to apply the constraint.
 *
 * @see ephysics_constraint_linear_limit_set() for linear moving limit
 * configuration.
 * @see ephysics_constraint_angular_limit_set() for angular moving limit
 * configuration.
 * @return A new constraint or @c NULL on erros.
 *
 * @see ephysics_constraint_del().
 *
 * @ingroup EPhysics_Constraint
 */
EAPI EPhysics_Constraint *ephysics_constraint_add(EPhysics_Body *body);

/**
 * @brief
 * Define the linear moving limits of a @p constraint.
 *
 * The linear limits are defined from the body's position on. The user will
 * want to limit the movements on X, Y and Z axis where lower == upper axis
 * will be locked, lower > upper axis is free, lower < upper axis is limited to
 * the range.
 *
 * The unit for every limits are defined on Evas coordinates.
 *
 * @param constraint The constraint to be set.
 * @param lower_x The lower linear moving limit on X axis.
 * @param upper_x The upper linear moving limit on X axis.
 * @param lower_y The lower linear moving limit on Y axis.
 * @param upper_y The upper linear moving limit on Y axis.
 * @param lower_z The lower linear moving limit on Z axis.
 * @param upper_z The upper linear moving limit on Z axis.
 *
 *
 * @see ephysics_constraint_linear_limit_get()
 * @ingroup EPhysics_Constraint
 */
EAPI void ephysics_constraint_linear_limit_set(EPhysics_Constraint *constraint, Evas_Coord lower_x, Evas_Coord upper_x, Evas_Coord lower_y, Evas_Coord upper_y, Evas_Coord lower_z, Evas_Coord upper_z);

/**
 * @brief
 * Get the linear moving limits of a @p constraint.
 *
 * @param constraint The constraint to get linear limits from.
 * @param lower_x Pointer to set with the lower limit to the X axis.
 * @param upper_x Pointer to set with the upper limit to the X axis.
 * @param lower_y Pointer to set with the lower limit to the Y axis.
 * @param upper_y Pointer to set with the upper limit to the Y axis.
 * @param lower_z Pointer to set with the lower limit to the Z axis.
 * @param upper_z Pointer to set with the upper limit to the Z axis.
 *
 * @see ephysics_constraint_linear_limit_set()
 * @ingroup EPhysics_Constraint
 */
EAPI void ephysics_constraint_linear_limit_get(const EPhysics_Constraint *constraint, Evas_Coord *lower_x, Evas_Coord *upper_x, Evas_Coord *lower_y, Evas_Coord *upper_y, Evas_Coord *lower_z, Evas_Coord *upper_z);

/**
 * @brief
 * Set the angular moving limits of a @p constraint.
 *
 * The angular moving limits is defined in degrees and will limit the moving on
 * Z axis - counter clockwise and clockwise directions.
 *
 * @param constraint The constraint to be set.
 * @param counter_clock_x Amount of degrees from 0.0 to 360.0 to limit counter
 * clockwise rotation on X axis.
 * @param clock_wise_x Amount of degrees from 0.0 to 360.0 to limit clockwise
 * rotation on X axis.
 * @param counter_clock_y Amount of degrees from 0.0 to 360.0 to limit counter
 * clockwise rotation o Y axis.
 * @param clock_wise_y Amount of degrees from 0.0 to 360.0 to limit clockwise
 * rotation on Y axis.
 * @param counter_clock_z Amount of degrees from 0.0 to 360.0 to limit
 * counter clockwise rotation on Z axis.
 * @param clock_wise_z Amount of degrees from 0.0 to 360.0 to limit clockwise
 * rotation on Z axis.
 *
 * @see ephysics_constraint_angular_limit_get()
 * @ingroup EPhysics_Constraint
 */
EAPI void ephysics_constraint_angular_limit_set(EPhysics_Constraint *constraint, double counter_clock_x, double clock_wise_x, double counter_clock_y, double clock_wise_y, double counter_clock_z, double clock_wise_z);

/**
 * @brief
 * Get the angular moving limits of a @p constraint.
 *
 * @param constraint The constraint to get the angular limits from.
 * @param counter_clock_x Pointer to set with the counter clockwise limmit
 * degrees on X axis.
 * @param clock_wise_x Pointer to set with the clockwise limit degrees on X axis.
 * @param counter_clock_y Pointer to set with the  counter clockwise limit
 * degrees on Y axis.
 * @param clock_wise_y Pointer to set with the clockwise limit degrees on Y axis.
 * @param counter_clock_z Pointer to set with the counter clockwise limit
 * degrees on Z axis.
 * @param clock_wise_z Pointer to set with the clockwise limit degrees on Z axis.
 *
 * @see ephysics_constraint_angular_limit_set()
 * @ingroup EPhysics_Constraint
 */
EAPI void ephysics_constraint_angular_limit_get(const EPhysics_Constraint *constraint, double *counter_clock_x, double *clock_wise_x, double *counter_clock_y, double *clock_wise_y, double *counter_clock_z, double *clock_wise_z);

/**
 * @brief
 * Deletes a physics constraint.
 *
 * @param constraint The constraint to be deleted.
 *
 * @see ephysics_constraint_linked_add() for more details.
 * @see ephysics_constraint_slider_add() for more details.
 *
 * @ingroup EPhysics_Constraint
 */
EAPI void ephysics_constraint_del(EPhysics_Constraint *constraint);

/**
 * @}
 */
#ifdef __cplusplus
}
#endif

#undef EAPI
#define EAPI

#endif
