zwritemask - specifies a write mask for the z-buffer of the current
unsigned long mask;
mask expects a mask indicating which z-buffer bitplanes are read only
and which can be written to. Z-buffer bitplanes that correspond
to zeros in the mask are read only. Z-buffer bitplanes that
correspond to ones in the mask can be written.
zwritemask specifies a mask used to control which z-buffer bitplanes are
written, and which are read only. A separate mask is maintained by each
of the framebuffers, normal, popup, overlay, and underlay. The mask
affects both writes to the z-buffer that are the result of z-buffer pixel
operation, and writes resulting from zclear operation.
zwritemask is ignored while drawing directly to the z-buffer, as when
zdraw is TRUE. In this case the current writemask applies to the z-buffer
as well as to the color bitplanes.
zwritemask is initialized when a window is created, and when gconfig is
called, to enable all z-buffer bitplanes.
gconfig, wmpack, writemask, zbuffer, zdraw
Currently z-buffer operation is supported only in the normal framebuffer.
To insure compatibility with future releases of the GL, make calls to
zwritemask only while draw mode is NORMALDRAW.
This subroutine does not function on IRIS-4D B or G models.
IRIS-4D GT and GTX models, RealityEngine models, and the Personal Iris,
currently support a subset of z write mask functionality. Specifically,
zwritemask either enables or disables the writing of all z-buffer
bitplanes. The mask passed to zwritemask will disable z-buffer writes if
it is zero; otherwise all z-buffer bitplanes are written. To assure
upward compatibility with the IRIS-4D VGX and other future models, call
zwritemask with mask equal to either 0 or 0xFFFFFFFF when all-or-nothing
update is desired.
On Impact and Infinite Reality individual z bitplanes are not maskable.
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