glRasterPos4f, glRasterPos4i, glRasterPos4s, glRasterPos2dv, glRaster-
Pos2fv, glRasterPos2iv, glRasterPos2sv, glRasterPos3dv, glRasterPos3fv,
glRasterPos3iv, glRasterPos3sv, glRasterPos4dv, glRasterPos4fv,
glRasterPos4iv, glRasterPos4sv - specify the raster position for pixel
operations
C SPECIFICATION
void GLAPIENTRY glRasterPos2d( GLdouble x,
GLdouble y )
void GLAPIENTRY glRasterPos2f( GLfloat x,
GLfloat y )
void GLAPIENTRY glRasterPos2i( GLint x,
GLint y )
void GLAPIENTRY glRasterPos2s( GLshort x,
GLshort y )
void GLAPIENTRY glRasterPos3d( GLdouble x,
GLdouble y,
GLdouble z )
void GLAPIENTRY glRasterPos3f( GLfloat x,
GLfloat y,
GLfloat z )
void GLAPIENTRY glRasterPos3i( GLint x,
GLint y,
GLint z )
void GLAPIENTRY glRasterPos3s( GLshort x,
GLshort y,
GLshort z )
void GLAPIENTRY glRasterPos4d( GLdouble x,
GLdouble y,
GLdouble z,
GLdouble w )
void GLAPIENTRY glRasterPos4f( GLfloat x,
GLfloat y,
GLfloat z,
GLfloat w )
void GLAPIENTRY glRasterPos4i( GLint x,
GLint y,
GLint z,
GLint w )
void GLAPIENTRY glRasterPos4s( GLshort x,
GLshort y,
GLshort z,
GLshort w )
PARAMETERS
x, y, z, w
Specify the x, y, z, and w object coordinates (if present) for
the raster position.
C SPECIFICATION
PARAMETERS
v Specifies a pointer to an array of two, three, or four elements,
specifying x, y, z, and w 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.
The current raster position consists of three window coordinates (x, y,
z), a clip coordinate value (w), an eye coordinate distance, a valid
bit, and associated color data and texture coordinates. The w coordi-
nate is a clip coordinate, because w is not projected to window coordi-
nates. glRasterPos4 specifies object coordinates x, y, z, and w
explicitly. glRasterPos3 specifies object coordinate x, y, and z
explicitly, while w is implicitly set to 1. glRasterPos2 uses the
argument values for x and y while implicitly setting z and w to 0 and
1.
The object coordinates presented by glRasterPos are treated just like
those of a glVertex command: They are transformed by the current mod-
elview and projection matrices and passed to the clipping stage. If
the vertex is not culled, then it is projected and scaled to window
coordinates, which become the new current raster position, and the
GL_CURRENT_RASTER_POSITION_VALID flag is set. If the vertex is culled,
then the valid bit is cleared and the current raster position and asso-
ciated color and texture coordinates are undefined.
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 calcula-
tion (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.
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). Finally, the distance from the
origin of the eye coordinate system to the vertex as transformed by
only the modelview matrix replaces GL_CURRENT_RASTER_DISTANCE.
Initially, the current raster position is (0, 0, 0, 1), the current
raster distance is 0, the valid bit is set, the associated RGBA color
is (1, 1, 1, 1), the associated color index is 1, and the associated
texture coordinates are (0, 0, 0, 1). In RGBA mode,
GL_CURRENT_RASTER_INDEX is always 1; in color index mode, the current
raster RGBA color always maintains its initial value.
When the GL_ARB_imaging extension is supported, there are distinct
raster texture coordinates for each texture unit. Each texture unit's
current ratster texture coordinates are updated by glRasterPos.
ERRORS
GL_INVALID_OPERATION is generated if glRasterPos 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_INDEX
glGet with argument GL_CURRENT_RASTER_TEXTURE_COORDS
SEE ALSO
glBitmap, glCopyPixels, glDrawArrays, glDrawElements,
glDrawRangeElements, glDrawPixels, glTexCoord, glTexGen, glVertex
GLRASTERPOS(3G)
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