zbsize(3G)

NAME
     zbsize - specifies the number of bit planes desired to comprise the Z
     buffer

C SPECIFICATION
     void zbsize(long planes)

PARAMETERS
     planes   is the number of bit planes requested to be configured as Z
              buffer planes. Only positive values are accepted.  The default
              is machine dependent, usually 24 or 32.

DESCRIPTION
     zbsize specifies how many bit planes are requested to be configured as Z
     buffer planes.  The constraints on planes are machine dependent.  Call
     getgdesc(GD_BITS_NORM_ZBUFFER) to determine the maximum number of bit
     planes available for Z buffer operation.

     zbsize takes effect only after gconfig has been called.  The number of
     bit planes granted for the Z buffer may not be exactly what was
     requested.  Call getgconfig(GC_BITS_ZBUFFER) to determine how many bit
     planes were configured as Z buffer planes.

     Since Z buffer bit planes are available only in the normal framebuffer,
     zbsize should be called only while draw mode is NORMALDRAW.

SEE ALSO
     gconfig, getgconfig, getgdesc, mssize

NOTES
     This routine is available only in immediate mode.

     Since most machines support only a finite set of Z buffer sizes, planes
     is rounded to the nearest supported size.

     IRIS-4D G, GT, GTX, VGX, and VGXT models, the Personal Iris, Iris Indy,
     Indigo Entry, XL, XS, XS24, XZ, Elan and Extreme systems do not support
     zbsize.

     The IRIS-4D RealityEngine models support only values of 0, 24 or 32
     planes.  On these models the Z buffer and the depth component in the
     multisample buffer are independent.  When the multisample buffer is
     requested in the current framebuffer configuration, it is recommended to
     call zbsize(0), as no Z buffer planes are required.

BUGS
     On the IRIS-4D RealityEngine models the framebuffer cannot be configured
     to consist of 32 Z buffer planes (or 32 depth planes in the multisample
     buffer) and 8 color planes for each of the RGB color buffers
     simultaneously.