GLRASTERPOS(3G) UNIX Programmer's Manual GLRASTERPOS(3G)
NAME
glRasterPos2d, glRasterPos2f, glRasterPos2i, glRasterPos2s,
glRasterPos3d, glRasterPos3f, glRasterPos3i, glRasterPos3s,
glRasterPos4d, glRasterPos4f, glRasterPos4i, glRasterPos4s,
glRasterPos2dv, glRasterPos2fv, glRasterPos2iv,
glRasterPos2sv, glRasterPos3dv, glRasterPos3fv,
glRasterPos3iv, glRasterPos3sv, glRasterPos4dv,
glRasterPos4fv, glRasterPos4iv, glRasterPos4sv - specify the
raster position for pixel operations
C SPECIFICATION
void glRasterPos2d( GLdouble x,
GLdouble y )
void glRasterPos2f( GLfloat x,
GLfloat y )
void glRasterPos2i( GLint x,
GLint y )
void glRasterPos2s( GLshort x,
GLshort y )
void glRasterPos3d( GLdouble x,
GLdouble y,
GLdouble z )
void glRasterPos3f( GLfloat x,
GLfloat y,
GLfloat z )
void glRasterPos3i( GLint x,
GLint y,
GLint z )
void glRasterPos3s( GLshort x,
GLshort y,
GLshort z )
void glRasterPos4d( GLdouble x,
GLdouble y,
GLdouble z,
GLdouble w )
void glRasterPos4f( GLfloat x,
GLfloat y,
GLfloat z,
GLfloat w )
void glRasterPos4i( GLint x,
GLint y,
GLint z,
GLint w )
void glRasterPos4s( GLshort x,
GLshort y,
GLshort z,
GLshort w )
PARAMETERS
x, y, z, w
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GLRASTERPOS(3G) UNIX Programmer's Manual GLRASTERPOS(3G)
Specify the x, y, z, and w object coordinates (if
present) for the raster position.
C SPECIFICATION
void glRasterPos2dv( const GLdouble *v )
void glRasterPos2fv( const GLfloat *v )
void glRasterPos2iv( const GLint *v )
void glRasterPos2sv( const GLshort *v )
void glRasterPos3dv( const GLdouble *v )
void glRasterPos3fv( const GLfloat *v )
void glRasterPos3iv( const GLint *v )
void glRasterPos3sv( const GLshort *v )
void glRasterPos4dv( const GLdouble *v )
void glRasterPos4fv( const GLfloat *v )
void glRasterPos4iv( const GLint *v )
void glRasterPos4sv( const GLshort *v )
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 coordi-
nates (x, y, z), a clip coordinate value (w), an eye coordi-
nate distance, a valid bit, and associated color data and
texture coordinates. The w coordinate is a clip coordinate,
because w is not projected to window coordinates.
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 modelview 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 associated color and texture coordinates
are undefined.
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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.
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.
NOTES
The raster position is modified both by glRasterPos and by
glBitmap.
When the raster position coordinates are invalid, drawing
commands that are based on the raster position are ignored
(that is, they do not result in changes to GL state).
Calling glDrawElements, or glDrawRangeElements may leave the
current color or index indeterminate. If glRasterPos is exe-
cuted while the current color or index is indeterminate, the
current raster color or current raster index remains
indeterminate.
To set a valid raster position outside the viewport, first
set a valid raster position, then call glBitmap with NULL as
the bitmap parameter.
When the GL_ARB_imaging extension is supported, there are
distinct raster texture coordinates for each texture unit.
Each texture unit's current raster texture coordinates are
updated by glRasterPos.
ERRORS
GL_INVALID_OPERATION is generated if glRasterPos is executed
between the execution of glBegin and the corresponding
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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(3G), glCopyPixels(3G), glDrawArrays(3G),
glDrawElements(3G), glDrawRangeElements(3G),
glDrawPixels(3G), glTexCoord(3G), glTexGen(3G), glVertex(3G)
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