lshade(3G)lshade(3G)NAMElshade - sets range of color indices used for depth-cueing
FORTRAN SPECIFICATION
subroutine lshade(lowin, highin, znear, zfar)
integer*2 lowin, highin
integer*4 znear, zfar
PARAMETERS
lowin expects the low-intensity color map index.
highin expects the high-intensity color map index.
znear expects the nearer screen z, to which highin is mapped.
zfar expects the farther screen z, to which lowin is mapped.
DESCRIPTIONlshade sets the range of color indices used for depth-cueing. The screen
z range [znear, zfar] is mapped linearly into the color index range
[highin, lowin]. Screen z values nearer than znear map to highin; screen
z values farther than zfar map to lowin.
The valid range for znear and zfar depends on the state of the GLCZRA
compatibility mode (see glcomp). If it is 0, the valid range depends on
the graphics hardware. When multisample is enabled, and multisample
buffers exist in the current framebuffer configuration in the current
drawmode, the minimum is the value returned by getgco(GCMZMI) and the
maximum is the value returned by getgco(GCMZMA). Otherwise, the minimum
is the value returned by getgco(GCZMIN) and the maximum is the value
returned by getgco(GCZMAX). If the state of the GLCZRA compatibility
mode is 1, the minimum is $0 and the maximum is $7FFFFF. The default is
lshade(0, 7, Zmin, Zmax), where Zmin and Zmax are the values such that
the full range supported by the graphics hardware is used.
Znear and zfar should be chosen to be consistent with the near and far
parameters passed to lsetde. If near < far, then znear should be less
than zfar. If near > far, then znear should be greater than zfar. In
either case, the range [near, far] should bound the range [znear, zfar].
SEE ALSO
depthc, getgde, glcomp, lsetde
NOTE
When using this routine, you should always explicitly set the GLCZRA mode
of glcomp because its default is different on different models.
Page 1
