RGBwritemask(3G)RGBwritemask(3G)NAMERGBwritemask - grants write access to a subset of available bitplanes
C SPECIFICATION
void RGBwritemask(red, green, blue)
short red, green, blue;
PARAMETERS
red expects the mask for the corresponding red bitplanes.
green expects the mask for the corresponding green bitplanes.
blue expects the mask for the corresponding blue bitplanes.
DESCRIPTIONRGBwritemask sets the red, green, and blue write mask components of the
currently active GL framebuffer, one of normal, popup, overlay, or
underlay as specified by drawmode, to the specified values. The alpha
mask component is set to enable writing to all alpha bitplanes. The
current framebuffer must be in RGB mode for the RGBwritemask command to
be applicable. All drawing into the color bitplanes of the current
framebuffer is masked by the current write mask. Write mask components
are retained in each draw mode, so when a draw mode is re-entered, the
red, green, blue, and alpha masks are reset to the last values specified
in that draw mode.
Each write mask component is an 8-bit mask, which allows changes only to
bitplanes corresponding to ones in the mask. For example,
RGBwritemask(0xF0,0x00,0x00) allows changes only to the 4 most
significant bits of red, and to all the bits of alpha. Bits 8 through 15
of each component specification are ignored, only bits 0 through 7 are
significant.
It is an error to call RGBwritemask while the current framebuffer is in
color map mode.
The write mask components of all framebuffers in RGB mode are set to 0xFF
when gconfig is called.
SEE ALSO
drawmode, gRGBmask, RGBmode, wmpack
NOTE
On Impact and Infinite Reality individual bits within a component cannot
be masked.
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