GLWINDOWPOS(3G)

NAME
glWindowPos - specify the raster position in window coordinates for pixel operations

C SPECIFICATION

void glWindowPos2s(GLshort x, GLshort y);

void glWindowPos2i(GLint x, GLint y);

void glWindowPos2f(GLfloat x, GLfloat y);

void glWindowPos2d(GLdouble x, GLdouble y);

void glWindowPos3s(GLshort x, GLshort y, GLshort z);

void glWindowPos3i(GLint x, GLint y, GLint z);

void glWindowPos3f(GLfloat x, GLfloat y, GLfloat z);

void glWindowPos3d(GLdouble x, GLdouble y, GLdouble z);

PARAMETERS

x, y, z
    Specify the x, y, z coordinates for the raster position.

C SPECIFICATION

void glWindowPos2sv(const GLshort * v);

void glWindowPos2iv(const GLint * v);

void glWindowPos2fv(const GLfloat * v);

void glWindowPos2dv(const GLdouble * v);

void glWindowPos3sv(const GLshort * v);

void glWindowPos3iv(const GLint * v);

void glWindowPos3fv(const GLfloat * v);

void glWindowPos3dv(const GLdouble * v);

PARAMETERS

v
    Specifies a pointer to an array of two or three elements, specifying x, y, z coordinates, respectively.

DESCRIPTION

The GL maintains a 3D position in window coordinates. This position, called the raster position, is used to position pixel and bitmap write operations. It is maintained with subpixel accuracy. See glBitmap(), glDrawPixels(), and glCopyPixels().

glWindowPos2 specifies the x and y coordinates, while z is implicitly set to 0. glWindowPos3 specifies all three coordinates. The w coordinate of the current raster position is always set to 1.0.

glWindowPos directly updates the x and y coordinates of the current raster position with the values specified. That is, the values are neither transformed by the current modelview and projection matrices, nor by the viewport-to-window transform. The z coordinate of the current raster position is updated in the following manner:

z = n f n + z × f - n ⁢ if ⁢ z <= 0 if ⁢ z >= 1 otherwise

where n is GL_DEPTH_RANGE's near value, and f is GL_DEPTH_RANGE's far value. See glDepthRange().

The specified coordinates are not clip-tested, causing the raster position to always be valid.

The current raster position also includes some associated color data and texture coordinates. If lighting is enabled, then GL_CURRENT_RASTER_COLOR (in RGBA mode) or GL_CURRENT_RASTER_INDEX (in color index mode) is set to the color produced by the lighting calculation (see glLight(), glLightModel(), and glShadeModel()). If lighting is disabled, current color (in RGBA mode, state variable GL_CURRENT_COLOR) or color index (in color index mode, state variable GL_CURRENT_INDEX) is used to update the current raster color. GL_CURRENT_RASTER_SECONDARY_COLOR (in RGBA mode) is likewise updated.

Likewise, GL_CURRENT_RASTER_TEXTURE_COORDS is updated as a function of GL_CURRENT_TEXTURE_COORDS, based on the texture matrix and the texture generation functions (see glTexGen()). The GL_CURRENT_RASTER_DISTANCE is set to the GL_CURRENT_FOG_COORD.

NOTES

glWindowPos is available only if the GL version is 1.4 or greater.

The raster position is modified by glRasterPos(), glBitmap(), and glWindowPos.

Calling glDrawElements(), or glDrawRangeElements() may leave the current color or index indeterminate. If glWindowPos is executed while the current color or index is indeterminate, the current raster color or current raster index remains indeterminate.

There are distinct raster texture coordinates for each texture unit. Each texture unit's current raster texture coordinates are updated by glWindowPos.

ERRORS

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

ASSOCIATED GETS

glGet() with argument GL_CURRENT_RASTER_POSITION

glGet() with argument GL_CURRENT_RASTER_POSITION_VALID

glGet() with argument GL_CURRENT_RASTER_DISTANCE

glGet() with argument GL_CURRENT_RASTER_COLOR

glGet() with argument GL_CURRENT_RASTER_SECONDARY_COLOR

glGet() with argument GL_CURRENT_RASTER_INDEX

glGet() with argument GL_CURRENT_RASTER_TEXTURE_COORDS

SEE ALSO

glBitmap(), glCopyPixels(), glDrawArrays(), glDrawElements(), glDrawRangeElements(), glDrawPixels(), glMultiTexCoord(), glRasterPos(), glTexCoord(), glTexGen(), glVertex()

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/.