glDepthRange(3G) OpenGL Reference glDepthRange(3G)
NAME
glDepthRange - specify mapping of depth values from normalized device
coordinates to window coordinates
C SPECIFICATION
void glDepthRange( GLclampd near,
GLclampd far )
PARAMETERS
near Specifies the mapping of the near clipping plane to window
coordinates. The initial value is 0.
far Specifies the mapping of the far clipping plane to window
coordinates. The initial value is 1.
DESCRIPTION
After clipping and division by w, depth coordinates range from -1 to 1,
corresponding to the near and far clipping planes. glDepthRange
specifies a linear mapping of the normalized depth coordinates in this
range to window depth coordinates. Regardless of the actual depth buffer
implementation, window coordinate depth values are treated as though they
range from 0 through 1 (like color components). Thus, the values
accepted by glDepthRange are both clamped to this range before they are
accepted.
The setting of (0,1) maps the near plane to 0 and the far plane to 1.
With this mapping, the depth buffer range is fully utilized.
NOTES
It is not necessary that near be less than far. Reverse mappings such as
near=1, and far=0 are acceptable.
ERRORS
GLINVALIDOPERATION is generated if glDepthRange is executed between the
execution of glBegin and the corresponding execution of glEnd.
ASSOCIATED GETS
glGet with argument GLDEPTHRANGE
MACHINE DEPENDENCIES
Although it is possible to reverse the depth mapping so that near is 1
and far is 0, doing so may cause severe depth-buffering artifacts on
InfiniteReality systems. (This is particularly true for 15-bit depth
buffers.) Therefore this practice is strongly discouraged.
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glDepthRange(3G) OpenGL Reference glDepthRange(3G)
SEE ALSO
glDepthFunc, glPolygonOffset, glViewport
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