NAME

       gl_SampleID - contains the index of the sample currently being processed

DECLARATION

       in int gl_SampleID ;.SH "DESCRIPTION"

       gl_SampleID is a fragment language input variable that contains the index of the sample
       currently being processed. This variable is in the range 0 to gl_NumSamples() - 1, where
       gl_NumSamples() is the total number of samples in each fragment for the current
       framebuffer (and thus 1 if rendering to a non-multisample buffer). Any static use of this
       variable in a fragment shader causes the entire shader to be evaluated per-sample rather
       than per-fragment.

       When rendering to a non-multisample buffer, or if multisample rasterization is disabled,
       gl_SampleID will always be zero.  gl_NumSamples() is the sample count of the framebuffer
       regardless of whether multisample rasterization is enabled or not.

VERSION SUPPORT

       ┌────────────┬───────────────────────────────────────────────────────────────────────────────────┐
       │            │        OpenGL Shading Language Version                                            │
       ├────────────┼──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┤
       │Variable    │ 1.10 │ 1.20 │ 1.30 │ 1.40 │ 1.50 │ 3.30 │ 4.00 │ 4.10 │ 4.20 │ 4.30 │ 4.40 │ 4.50 │
       │Name        │      │      │      │      │      │      │      │      │      │      │      │      │
       ├────────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┤
       │gl_SampleID │  -   │  -   │  -   │  -   │  -   │  -   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │
       └────────────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┘

SEE ALSO

       gl_SamplePosition(), gl_NumSamples()

COPYRIGHT

       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.
       http://opencontent.org/openpub/.

COPYRIGHT

       Copyright © 2011-2014 Khronos Group

[FIXME: source]                             07/22/2015                            GL_SAMPLEID(3G)