GL_PRIMITIVEID(3G)              [FIXME: manual]             GL_PRIMITIVEID(3G)

NAME
       gl_PrimitiveID - contains the index of the current primitive

DECLARATION
       // In tessellation control, tessellation evaluation, and
       // fragment shaders


       in int gl_PrimitiveID ;

       // In geometry shaders


       out int gl_PrimitiveID ;

DESCRIPTION
       gl_PrimitiveID is a tessellation control, tessellation evaluation and
       fragment language input variable. For the tessellation control and
       tessellation evaluation languages, it holds the number of primitives
       processed by the shader since the current set of rendering primitives
       was started. The first primitive processed by the drawing command is
       numbered zero and the primitive ID counter is incremented after every
       individual point, line or triangle primitive is processed. For
       triangles drawn in point or line mode, the primitive ID counter is
       incremented only once, even through multiple points or lines may
       actually be drawn. Restarting a primitive topology using the primitive
       restart index has no effect on the primitive ID counter.

       In the geometry language, gl_PrimitiveID is an output variable that is
       passed to the corresponding gl_PrimitiveID input variable in the
       fragment shader. If no geomery shader is present then gl_PrimitiveID in
       the fragment language behaves identically as it would in the
       tessellation control and evaluation languages. If a geometry shader is
       present but does not write to gl_PrimitiveID, the value of
       gl_PrimitiveID in the fragment shader is undefined.

VERSION SUPPORT

       +---------------+-----------------------------------------------------------------------------------+
       |               |                          OpenGL Shading Language Version                          |
       +---------------+------+------+------+------+------+------+------+------+------+------+------+------+
       |Function Name  | 1.10 | 1.20 | 1.30 | 1.40 | 1.50 | 3.30 | 4.00 | 4.10 | 4.20 | 4.30 | 4.40 | 4.50 |
       +---------------+------+------+------+------+------+------+------+------+------+------+------+------+
       |gl_PrimitiveID |  -   |  -   |  -   |  -   | <?>  | <?>  | <?>  | <?>  | <?>  | <?>  | <?>  | <?>  |
       |(Fragment and  |      |      |      |      |      |      |      |      |      |      |      |      |
       |Geometry       |      |      |      |      |      |      |      |      |      |      |      |      |
       |Languages)     |      |      |      |      |      |      |      |      |      |      |      |      |
       +---------------+------+------+------+------+------+------+------+------+------+------+------+------+
       |gl_PrimitiveID |  -   |  -   |  -   |  -   |  -   |  -   | <?>  | <?>  | <?>  | <?>  | <?>  | <?>  |
       |(Tessellation  |      |      |      |      |      |      |      |      |      |      |      |      |
       |Control and    |      |      |      |      |      |      |      |      |      |      |      |      |
       |Evaluation     |      |      |      |      |      |      |      |      |      |      |      |      |
       |Languages)     |      |      |      |      |      |      |      |      |      |      |      |      |
       +---------------+------+------+------+------+------+------+------+------+------+------+------+------+

SEE ALSO
       gl_InstanceID(), gl_VertexID(), gl_PrimitiveIDIn()

COPYRIGHT
       Copyright (C) 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 (C) 2011-2014 Khronos Group

[FIXME: source]                   05/21/2022                GL_PRIMITIVEID(3G)