GLENABLE(3G)

NAME
glEnable - enable or disable server-side GL capabilities

C SPECIFICATION

void glEnable(GLenum cap);

PARAMETERS

cap
    Specifies a symbolic constant indicating a GL capability.

C SPECIFICATION

void glDisable(GLenum cap);

PARAMETERS

cap
    Specifies a symbolic constant indicating a GL capability.

DESCRIPTION

glEnable and glDisable() enable and disable various capabilities. Use glIsEnabled() or glGet() to determine the current setting of any capability. The initial value for each capability with the exception of GL_DITHER and GL_MULTISAMPLE is GL_FALSE. The initial value for GL_DITHER and GL_MULTISAMPLE is GL_TRUE.

Both glEnable and glDisable() take a single argument, cap, which can assume one of the following values:

GL_ALPHA_TEST

    If enabled, do alpha testing. See glAlphaFunc().

GL_AUTO_NORMAL

    If enabled, generate normal vectors when either GL_MAP2_VERTEX_3 or GL_MAP2_VERTEX_4 is used to generate vertices. See glMap2().

GL_BLEND

    If enabled, blend the computed fragment color values with the values in the color buffers. See glBlendFunc().

GL_CLIP_PLANEi

    If enabled, clip geometry against user-defined clipping plane i. See glClipPlane().

GL_COLOR_LOGIC_OP

    If enabled, apply the currently selected logical operation to the computed fragment color and color buffer values. See glLogicOp().

GL_COLOR_MATERIAL

    If enabled, have one or more material parameters track the current color. See glColorMaterial().

GL_COLOR_SUM

    If enabled and no fragment shader is active, add the secondary color value to the computed fragment color. See glSecondaryColor().

GL_COLOR_TABLE

    If enabled, perform a color table lookup on the incoming RGBA color values. See glColorTable().

GL_CONVOLUTION_1D

    If enabled, perform a 1D convolution operation on incoming RGBA color values. See glConvolutionFilter1D().

GL_CONVOLUTION_2D

    If enabled, perform a 2D convolution operation on incoming RGBA color values. See glConvolutionFilter2D().

GL_CULL_FACE

    If enabled, cull polygons based on their winding in window coordinates. See glCullFace().

GL_DEPTH_TEST

    If enabled, do depth comparisons and update the depth buffer. Note that even if the depth buffer exists and the depth mask is non-zero, the depth buffer is not updated if the depth test is disabled. See glDepthFunc() and glDepthRange().

GL_DITHER

    If enabled, dither color components or indices before they are written to the color buffer.

GL_FOG

    If enabled and no fragment shader is active, blend a fog color into the post-texturing color. See glFog().

GL_HISTOGRAM

    If enabled, histogram incoming RGBA color values. See glHistogram().

GL_INDEX_LOGIC_OP

    If enabled, apply the currently selected logical operation to the incoming index and color buffer indices. See glLogicOp().

GL_LIGHTi

    If enabled, include light i in the evaluation of the lighting equation. See glLightModel() and glLight().

GL_LIGHTING

    If enabled and no vertex shader is active, use the current lighting parameters to compute the vertex color or index. Otherwise, simply associate the current color or index with each vertex. See glMaterial(), glLightModel(), and glLight().

GL_LINE_SMOOTH

    If enabled, draw lines with correct filtering. Otherwise, draw aliased lines. See glLineWidth().

GL_LINE_STIPPLE

    If enabled, use the current line stipple pattern when drawing lines. See glLineStipple().

GL_MAP1_COLOR_4

    If enabled, calls to glEvalCoord1(), glEvalMesh1(), and glEvalPoint1() generate RGBA values. See glMap1().

GL_MAP1_INDEX

    If enabled, calls to glEvalCoord1(), glEvalMesh1(), and glEvalPoint1() generate color indices. See glMap1().

GL_MAP1_NORMAL

    If enabled, calls to glEvalCoord1(), glEvalMesh1(), and glEvalPoint1() generate normals. See glMap1().

GL_MAP1_TEXTURE_COORD_1

    If enabled, calls to glEvalCoord1(), glEvalMesh1(), and glEvalPoint1() generate s texture coordinates. See glMap1().

GL_MAP1_TEXTURE_COORD_2

    If enabled, calls to glEvalCoord1(), glEvalMesh1(), and glEvalPoint1() generate s and t texture coordinates. See glMap1().

GL_MAP1_TEXTURE_COORD_3

    If enabled, calls to glEvalCoord1(), glEvalMesh1(), and glEvalPoint1() generate s, t, and r texture coordinates. See glMap1().

GL_MAP1_TEXTURE_COORD_4

    If enabled, calls to glEvalCoord1(), glEvalMesh1(), and glEvalPoint1() generate s, t, r, and q texture coordinates. See glMap1().

GL_MAP1_VERTEX_3

    If enabled, calls to glEvalCoord1(), glEvalMesh1(), and glEvalPoint1() generate x, y, and z vertex coordinates. See glMap1().

GL_MAP1_VERTEX_4

    If enabled, calls to glEvalCoord1(), glEvalMesh1(), and glEvalPoint1() generate homogeneous x, y, z, and w vertex coordinates. See glMap1().

GL_MAP2_COLOR_4

    If enabled, calls to glEvalCoord2(), glEvalMesh2(), and glEvalPoint2() generate RGBA values. See glMap2().

GL_MAP2_INDEX

    If enabled, calls to glEvalCoord2(), glEvalMesh2(), and glEvalPoint2() generate color indices. See glMap2().

GL_MAP2_NORMAL

    If enabled, calls to glEvalCoord2(), glEvalMesh2(), and glEvalPoint2() generate normals. See glMap2().

GL_MAP2_TEXTURE_COORD_1

    If enabled, calls to glEvalCoord2(), glEvalMesh2(), and glEvalPoint2() generate s texture coordinates. See glMap2().

GL_MAP2_TEXTURE_COORD_2

    If enabled, calls to glEvalCoord2(), glEvalMesh2(), and glEvalPoint2() generate s and t texture coordinates. See glMap2().

GL_MAP2_TEXTURE_COORD_3

    If enabled, calls to glEvalCoord2(), glEvalMesh2(), and glEvalPoint2() generate s, t, and r texture coordinates. See glMap2().

GL_MAP2_TEXTURE_COORD_4

    If enabled, calls to glEvalCoord2(), glEvalMesh2(), and glEvalPoint2() generate s, t, r, and q texture coordinates. See glMap2().

GL_MAP2_VERTEX_3

    If enabled, calls to glEvalCoord2(), glEvalMesh2(), and glEvalPoint2() generate x, y, and z vertex coordinates. See glMap2().

GL_MAP2_VERTEX_4

    If enabled, calls to glEvalCoord2(), glEvalMesh2(), and glEvalPoint2() generate homogeneous x, y, z, and w vertex coordinates. See glMap2().

GL_MINMAX

    If enabled, compute the minimum and maximum values of incoming RGBA color values. See glMinmax().

GL_MULTISAMPLE

    If enabled, use multiple fragment samples in computing the final color of a pixel. See glSampleCoverage().

GL_NORMALIZE

    If enabled and no vertex shader is active, normal vectors are normalized to unit length after transformation and before lighting. This method is generally less efficient than GL_RESCALE_NORMAL. See glNormal() and glNormalPointer().

GL_POINT_SMOOTH

    If enabled, draw points with proper filtering. Otherwise, draw aliased points. See glPointSize().

GL_POINT_SPRITE

    If enabled, calculate texture coordinates for points based on texture environment and point parameter settings. Otherwise texture coordinates are constant across points.

GL_POLYGON_OFFSET_FILL

    If enabled, and if the polygon is rendered in GL_FILL mode, an offset is added to depth values of a polygon's fragments before the depth comparison is performed. See glPolygonOffset().

GL_POLYGON_OFFSET_LINE

    If enabled, and if the polygon is rendered in GL_LINE mode, an offset is added to depth values of a polygon's fragments before the depth comparison is performed. See glPolygonOffset().

GL_POLYGON_OFFSET_POINT

    If enabled, an offset is added to depth values of a polygon's fragments before the depth comparison is performed, if the polygon is rendered in GL_POINT mode. See glPolygonOffset().

GL_POLYGON_SMOOTH

    If enabled, draw polygons with proper filtering. Otherwise, draw aliased polygons. For correct antialiased polygons, an alpha buffer is needed and the polygons must be sorted front to back.

GL_POLYGON_STIPPLE

    If enabled, use the current polygon stipple pattern when rendering polygons. See glPolygonStipple().

GL_POST_COLOR_MATRIX_COLOR_TABLE

    If enabled, perform a color table lookup on RGBA color values after color matrix transformation. See glColorTable().

GL_POST_CONVOLUTION_COLOR_TABLE

    If enabled, perform a color table lookup on RGBA color values after convolution. See glColorTable().

GL_RESCALE_NORMAL

    If enabled and no vertex shader is active, normal vectors are scaled after transformation and before lighting by a factor computed from the modelview matrix. If the modelview matrix scales space uniformly, this has the effect of restoring the transformed normal to unit length. This method is generally more efficient than GL_NORMALIZE. See glNormal() and glNormalPointer().

GL_SAMPLE_ALPHA_TO_COVERAGE

    If enabled, compute a temporary coverage value where each bit is determined by the alpha value at the corresponding sample location. The temporary coverage value is then ANDed with the fragment coverage value.

GL_SAMPLE_ALPHA_TO_ONE

    If enabled, each sample alpha value is replaced by the maximum representable alpha value.

GL_SAMPLE_COVERAGE

    If enabled, the fragment's coverage is ANDed with the temporary coverage value. If GL_SAMPLE_COVERAGE_INVERT is set to GL_TRUE, invert the coverage value. See glSampleCoverage().

GL_SEPARABLE_2D

    If enabled, perform a two-dimensional convolution operation using a separable convolution filter on incoming RGBA color values. See glSeparableFilter2D().

GL_SCISSOR_TEST

    If enabled, discard fragments that are outside the scissor rectangle. See glScissor().

GL_STENCIL_TEST

    If enabled, do stencil testing and update the stencil buffer. See glStencilFunc() and glStencilOp().

GL_TEXTURE_1D

    If enabled and no fragment shader is active, one-dimensional texturing is performed (unless two- or three-dimensional or cube-mapped texturing is also enabled). See glTexImage1D().

GL_TEXTURE_2D

    If enabled and no fragment shader is active, two-dimensional texturing is performed (unless three-dimensional or cube-mapped texturing is also enabled). See glTexImage2D().

GL_TEXTURE_3D

    If enabled and no fragment shader is active, three-dimensional texturing is performed (unless cube-mapped texturing is also enabled). See glTexImage3D().

GL_TEXTURE_CUBE_MAP

    If enabled and no fragment shader is active, cube-mapped texturing is performed. See glTexImage2D().

GL_TEXTURE_GEN_Q

    If enabled and no vertex shader is active, the q texture coordinate is computed using the texture generation function defined with glTexGen(). Otherwise, the current q texture coordinate is used. See glTexGen().

GL_TEXTURE_GEN_R

    If enabled and no vertex shader is active, the r texture coordinate is computed using the texture generation function defined with glTexGen(). Otherwise, the current r texture coordinate is used. See glTexGen().

GL_TEXTURE_GEN_S

    If enabled and no vertex shader is active, the s texture coordinate is computed using the texture generation function defined with glTexGen(). Otherwise, the current s texture coordinate is used. See glTexGen().

GL_TEXTURE_GEN_T

    If enabled and no vertex shader is active, the t texture coordinate is computed using the texture generation function defined with glTexGen(). Otherwise, the current t texture coordinate is used. See glTexGen().

GL_VERTEX_PROGRAM_POINT_SIZE

    If enabled and a vertex shader is active, then the derived point size is taken from the (potentially clipped) shader builtin gl_PointSize and clamped to the implementation-dependent point size range.

GL_VERTEX_PROGRAM_TWO_SIDE

    If enabled and a vertex shader is active, it specifies that the GL will choose between front and back colors based on the polygon's face direction of which the vertex being shaded is a part. It has no effect on points or lines.

NOTES

GL_POLYGON_OFFSET_FILL, GL_POLYGON_OFFSET_LINE, GL_POLYGON_OFFSET_POINT, GL_COLOR_LOGIC_OP, and GL_INDEX_LOGIC_OP are available only if the GL version is 1.1 or greater.

GL_RESCALE_NORMAL, and GL_TEXTURE_3D are available only if the GL version is 1.2 or greater.

GL_MULTISAMPLE, GL_SAMPLE_ALPHA_TO_COVERAGE, GL_SAMPLE_ALPHA_TO_ONE, GL_SAMPLE_COVERAGE, GL_TEXTURE_CUBE_MAP are available only if the GL version is 1.3 or greater.

GL_POINT_SPRITE, GL_VERTEX_PROGRAM_POINT_SIZE, and GL_VERTEX_PROGRAM_TWO_SIDE is available only if the GL version is 2.0 or greater.

GL_COLOR_TABLE, GL_CONVOLUTION_1D, GL_CONVOLUTION_2D, GL_HISTOGRAM, GL_MINMAX, GL_POST_COLOR_MATRIX_COLOR_TABLE, GL_POST_CONVOLUTION_COLOR_TABLE, and GL_SEPARABLE_2D are available only if ARB_imaging is returned from glGet() with an argument of GL_EXTENSIONS.

For OpenGL versions 1.3 and greater, or when ARB_multitexture is supported, GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D, GL_TEXTURE_GEN_S, GL_TEXTURE_GEN_T, GL_TEXTURE_GEN_R, and GL_TEXTURE_GEN_Q enable or disable the respective state for the active texture unit specified with glActiveTexture().

ERRORS

GL_INVALID_ENUM is generated if cap is not one of the values listed previously.

GL_INVALID_OPERATION is generated if glEnable or glDisable() is executed between the execution of glBegin() and the corresponding execution of glEnd().

ASSOCIATED GETS

glIsEnabled()

glGet()

SEE ALSO

glActiveTexture(), glAlphaFunc(), glBlendFunc(), glClipPlane(), glColorMaterial(), glCullFace(), glDepthFunc(), glDepthRange(), glEnableClientState(), glFog(), glGet(), glIsEnabled(), glLight(), glLightModel(), glLineWidth(), glLineStipple(), glLogicOp(), glMap1(), glMap2(), glMaterial(), glNormal(), glNormalPointer(), glPointSize(), glPolygonMode(), glPolygonOffset(), glPolygonStipple(), glSampleCoverage(), glScissor(), glStencilFunc(), glStencilOp(), glTexGen(), glTexImage1D(), glTexImage2D(), glTexImage3D()

COPYRIGHT

Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.