zwrite(3G)zwrite(3G)NAMEzwrite - specifies a write mask for the z-buffer of the current
framebuffer
FORTRAN 77 SPECIFICATIONzwrite(mask)
integer*4 mask;
PARAMETERS
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.
DESCRIPTIONzwrite 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.
zwrite 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.
zwrite is initialized when a window is created, and when gconfi is
called, to enable all z-buffer bitplanes.
SEE ALSO
gconfi, wmpack, writem, zbuffer, zdraw
NOTES
Currently z-buffer operation is supported only in the normal framebuffer.
To insure compatibility with future releases of the GL, make calls to
zwrite only while draw mode is NORMAL.
BUGS
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,
zwrite either enables or disables the writing of all z-buffer bitplanes.
The mask passed to zwrite 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 zwrite
with mask equal to either 0 or $FFFFFFFF when all-or-nothing update is
desired.
On Impact and Infinite Reality individual z bitplanes are not maskable.
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