gl_SampleMask — specifies the sample coverage mask for the current fragment
out int gl_SampleMask ;
gl_SampleMask is a fragment language output array that may be
used to set the sample mask for the fragment being processed. Coverage for the current
fragment will become the logical AND of the coverage mask and the output
That is, setting a bit in
gl_SampleMask to zero will cause the
corresponding sample to be considered uncovered for the purposes of multisample fragment operations. However,
setting sample mask bits back to one will never enable samples not covered by the original primitive.
Bit B of mask
gl_SampleMask[M] corresponds to sample
32 * M + B. This array must be sized in the fragment shader
either implicitly or explicitly to be the same size as the implementation-dependent maximum
sample-mask (as an array of 32-bit elements), determined by the maximum number of samples.
If the fragment shader statically assigns a value to
sample mask will be undefined for any array elements of any fragment shader invocation that
fails to assign a value. If a shader does not statically assign a value to
the sample mask has no effect on the processing of a fragment.
If the fragment shader is being evaluated at any frequency other than per-fragment, bits within
the sample mask not corresponding to the current fragment shader invocation are ignored.
|OpenGL Shading Language Version|
Copyright © 2011-2014 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. https://opencontent.org/openpub/.