fglRasterPos(3G) OpenGL Reference fglRasterPos(3G)NAME
fglRasterPos2d, fglRasterPos2f, fglRasterPos2i, fglRasterPos2s,
fglRasterPos3d, fglRasterPos3f, fglRasterPos3i, fglRasterPos3s,
fglRasterPos4d, fglRasterPos4f, fglRasterPos4i, fglRasterPos4s,
fglRasterPos2dv, fglRasterPos2fv, fglRasterPos2iv, fglRasterPos2sv,
fglRasterPos3dv, fglRasterPos3fv, fglRasterPos3iv, fglRasterPos3sv,
fglRasterPos4dv, fglRasterPos4fv, fglRasterPos4iv, fglRasterPos4sv -
specify the raster position for pixel operations
FORTRAN SPECIFICATION
SUBROUTINE fglRasterPos2d( REAL*4 x,
REAL*4 y )
SUBROUTINE fglRasterPos2f( REAL*4 x,
REAL*4 y )
SUBROUTINE fglRasterPos2i( INTEGER*4 x,
INTEGER*4 y )
SUBROUTINE fglRasterPos2s( INTEGER*2 x,
INTEGER*2 y )
SUBROUTINE fglRasterPos3d( REAL*4 x,
REAL*4 y,
REAL*4 z )
SUBROUTINE fglRasterPos3f( REAL*4 x,
REAL*4 y,
REAL*4 z )
SUBROUTINE fglRasterPos3i( INTEGER*4 x,
INTEGER*4 y,
INTEGER*4 z )
SUBROUTINE fglRasterPos3s( INTEGER*2 x,
INTEGER*2 y,
INTEGER*2 z )
SUBROUTINE fglRasterPos4d( REAL*4 x,
REAL*4 y,
REAL*4 z,
REAL*4 w )
SUBROUTINE fglRasterPos4f( REAL*4 x,
REAL*4 y,
REAL*4 z,
REAL*4 w )
SUBROUTINE fglRasterPos4i( INTEGER*4 x,
INTEGER*4 y,
INTEGER*4 z,
INTEGER*4 w )
SUBROUTINE fglRasterPos4s( INTEGER*2 x,
INTEGER*2 y,
INTEGER*2 z,
INTEGER*2 w )
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fglRasterPos(3G) OpenGL Reference fglRasterPos(3G)PARAMETERS
x, y, z, w
Specify the x, y, z, and w object coordinates (if present) for
the raster position.
FORTRAN SPECIFICATION
SUBROUTINE fglRasterPos2dv( CHARACTER*8 v )
SUBROUTINE fglRasterPos2fv( CHARACTER*8 v )
SUBROUTINE fglRasterPos2iv( CHARACTER*8 v )
SUBROUTINE fglRasterPos2sv( CHARACTER*8 v )
SUBROUTINE fglRasterPos3dv( CHARACTER*8 v )
SUBROUTINE fglRasterPos3fv( CHARACTER*8 v )
SUBROUTINE fglRasterPos3iv( CHARACTER*8 v )
SUBROUTINE fglRasterPos3sv( CHARACTER*8 v )
SUBROUTINE fglRasterPos4dv( CHARACTER*8 v )
SUBROUTINE fglRasterPos4fv( CHARACTER*8 v )
SUBROUTINE fglRasterPos4iv( CHARACTER*8 v )
SUBROUTINE fglRasterPos4sv( CHARACTER*8 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 fglBitmap,
fglDrawPixels, and fglCopyPixels.
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 coordinate is a
clip coordinate, because w is not projected to window coordinates.
fglRasterPos4 specifies object coordinates x, y, z, and w explicitly.
fglRasterPos3 specifies object coordinate x, y, and z explicitly, while w
is implicitly set to 1. fglRasterPos2 uses the argument values for x and
y while implicitly setting z and w to 0 and 1.
The object coordinates presented by fglRasterPos are treated just like
those of a fglVertex 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.
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
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fglRasterPos(3G) OpenGL Reference fglRasterPos(3G)
calculation (see fglLight, fglLightModel, and
fglShadeModel). 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 fglTexGen). 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 fglRasterPos and by fglBitmap.
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 fglDrawElements, or fglDrawRangeElements may leave the current
color or index indeterminate. If fglRasterPos is executed 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 fglBitmap with NULL as the bitmap parameter.
ERRORS
GL_INVALID_OPERATION is generated if fglRasterPos is executed between the
execution of fglBegin and the corresponding execution of fglEnd.
ASSOCIATED GETS
fglGet with argument GL_CURRENT_RASTER_POSITION
fglGet with argument GL_CURRENT_RASTER_POSITION_VALID
fglGet with argument GL_CURRENT_RASTER_DISTANCE
fglGet with argument GL_CURRENT_RASTER_COLOR
fglGet with argument GL_CURRENT_RASTER_INDEX
fglGet with argument GL_CURRENT_RASTER_TEXTURE_COORDS
SEE ALSO
fglBitmap, fglCopyPixels, fglDrawArrays, fglDrawElements,
fglDrawRangeElements, fglDrawPixels, fglLight, fglLightModel,
fglShadeModel, fglTexCoord, fglTexGen, fglVertex
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