gl.RasterPos(x, y[, z, w])
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.
The object coordinates presented by gl.RasterPos()
are treated just like those of a gl.Vertex() 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 calculation (see gl.Light(), gl.LightModel(), and gl.ShadeModel()).
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 gl.TexGen for details.). 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.
The raster position is modified by gl.RasterPos()
and gl.Bitmap().
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 gl.DrawElements() may leave the current color or index indeterminate. If gl.RasterPos()
is executed while the current color or index is indeterminate, the current raster color or current raster index remains
indeterminate.
Alternatively, gl.RasterPos()
can also be called with a single table argument containing two to four coordinates
to set as the new raster position.
Please consult an OpenGL reference manual for more information.
#GL_INVALID_OPERATION
is generated if gl.RasterPos()
is executed between the execution of gl.Begin() and the corresponding execution of gl.End().
#GL_CURRENT_RASTER_POSITION
gl.Get() with argument #GL_CURRENT_RASTER_POSITION_VALID
gl.Get() with argument #GL_CURRENT_RASTER_DISTANCE
gl.Get() with argument #GL_CURRENT_RASTER_COLOR
gl.Get() with argument #GL_CURRENT_RASTER_INDEX
gl.Get() with argument #GL_CURRENT_RASTER_TEXTURE_COORDS