mssize(3G)mssize(3G)NAMEmssize - specifies multisample buffer configuration
C SPECIFICATION
void mssize(long samples, long zsize, long ssize)
PARAMETERS
samples is the number of samples to be stored at each framebuffer pixel
location. The default is zero.
zsize is the number of bits per depth component desired in the
multisample buffer.
ssize is the number of bits per stencil field desired in the
multisample buffer.
DESCRIPTION
By default the normal framebuffer is configured to store one sample at
each pixel location. This sample can include one, two, or four color
buffers, a single depth value, and a stencil value. mssize allows
configuration of the normal framebuffer to store many samples at each
pixel location. Because the samples specified by mssize are distinct
from the single sample that is normally stored, the default mssize of
zero corresponds to the default single-sample configuration.
mssize takes effect when gconfig is called. The requested sample count
and multisample buffer sizes are considered along with the other gconfig
requests, such as double buffering and RGB mode. Multisample red, green,
blue, and alpha component sizes are made identical to those in the normal
framebuffer.
For example, consider the following request:
RGBmode();
doublebuffer();
mssize(4,32,1);
zbsize(0);
stensize(0);
gconfig();
If this request is honored, the framebuffer will be configured with 2 RGB
color buffers (front and back) and 4 separate samples each consisting of
a single RGB color, a 32-bit depth value, and a 1-bit stencil value.
Note that no depth or stencil bits are directly associated with the front
and back color buffers, because none were requested.
Likewise, the request:
Page 1
mssize(3G)mssize(3G)RGBmode();
doublebuffer();
mssize(4,32,1);
zbsize(32);
stensize(1);
gconfig();
if granted, results in the same multisample configuration, but includes a
regular zbuffer and a stencil buffer.
The samples, zsize and ssize granted may not be exactly what was
requested. After a call to mssize and gconfig call getgconfig to
determine how the framebuffer was actually configured.
Just as the default single sample at each framebuffer pixel is considered
to be located at the center of that pixel, the samples multisamples each
have a fixed location near the corresponding pixel center. These
locations are chosen by the GL to provide good area sampling.
SEE ALSO
gconfig, getgconfig, msalpha, msmask, mspattern, mssize, multisample,
RGBsize, stensize, zbsize
NOTES
This routine is available only in immediate mode.
IRIS-4D G, GT, GTX, VGX, and VGXT models, the Personal Iris, Indigo
Entry, Indy, XL, XS, XS24, XZ, Elan and Extreme systems do not support
mssize.
Although separate specifications are allowed for normal and multisample
z-buffer sizes, and for normal and multisample stencil buffer sizes,
implementations need not support differing non-zero buffer sizes.
The IRIS-4D RealityEngine models support at least the following values
for samples: 0, 4, 8, 16 with a zsize of 0, 24 or 32 and with an ssize
of 0 through 8.
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.
On the IRIS-4D RealityEngine models the framebuffer cannot be configured
to consist of more than 1 stencil plane in the multisample buffer, and 8
color planes for each of the RGB color buffers simultaneously.
Page 2
