lshade(3G)

NAME
     lshade - 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.

DESCRIPTION
     lshade 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.