lRGBra(3G)

NAME
     lRGBra - sets the range of RGB colors used for depth-cueing

FORTRAN 77 SPECIFICATION
     subroutine lRGBra(rmin, gmin, bmin, rmax, gmax, bmax, znear, zfar)
     integer*2 rmin, gmin, bmin, rmax, gmax, bmax
     integer*4 znear, zfar

PARAMETERS
     rmin   expects the minimum value to be stored in the red bitplanes.

     gmin   expects the minimum value to be stored in the green bitplanes.

     bmin   expects the minimum value to be stored in the blue bitplanes.

     rmax   expects the maximum value to be stored in the red bitplanes.

     gmax   expects the maximum value to be stored in the green bitplanes.

     bmax   expects the maximum value to be stored in the blue bitplanes.

     znear  expects the nearer screen z, to which the maximum colors are
            mapped.

     zfar   expects the farther screen z, to which the minimum colors are
            mapped.

DESCRIPTION
     lRGBra sets the range of RGB colors used for depth-cueing in RGB mode.
     The screen z range [znear, zfar] is mapped linearly into the RGB color
     range [ (rmax,gmax,bmax), (rmin,gmin,bmin) ].  Screen z values nearer
     than znear are mapped to (rmax,gmax,bmax); screen z values farther than
     zfar are mapped to (rmin,gmin,bmin).

     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.  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.