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1 | <?xml version="1.0" encoding="UTF-8"?> |
2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd"> | |
3 | <!-- saved from url=(0013)about:internet --> | |
4 | <?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="stylesheet" type="text/css" href="opengl-man.css" /><title>gl_PrimitiveID - OpenGL Shading Language (GLSL)</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="gl_PrimitiveID"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>gl_PrimitiveID — contains the index of the current primitive</p></div><div class="refsynopsisdiv"><h2>Declaration</h2><div class="funcsynopsis"><code class="function">in int gl_PrimitiveID;</code> (Tessellation control, tessellation evaluation and fragment languages)<br /><code class="function">out int gl_PrimitiveID;</code> (Geometry language) | |
5 | </div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p> | |
6 | <code class="function">gl_PrimitiveID</code> is a tessellation control, tessellation evaluation | |
7 | and fragment language input variable. For the tessellation control and tessellation | |
8 | evaluation languages, it holds the number of primitives processed by | |
9 | the shader since the current set of rendering primitives was started. The first | |
10 | primitive processed by the drawing command is numbered zero and the primitive ID counter is incremented after every individual point, line | |
11 | or triangle primitive is processed. For triangles drawn in point or line mode, the | |
12 | primitive ID counter is incremented only once, even through multiple points or lines | |
13 | may actually be drawn. Restarting a primitive topology using the primitive restart | |
14 | index has no effect on the primitive ID counter. | |
15 | </p><p> | |
16 | In the geometry language, <code class="function">gl_PrimitiveID</code> is an output | |
17 | variable that is passed to the corresponding <code class="function">gl_PrimitiveID</code> input | |
18 | variable in the fragment shader. If no geomery shader is present then <code class="function">gl_PrimitiveID</code> | |
19 | in the fragment language behaves identically as it would in the tessellation control and evaluation | |
20 | languages. If a geometry shader is present but does not write to <code class="function">gl_PrimitiveID</code>, | |
21 | the value of <code class="function">gl_PrimitiveID</code> in the fragment shader is undefined. | |
22 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="versions"></a><h2>Version Support</h2><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="center" /><col align="center" /></colgroup><thead><tr><th align="left"><span class="bold"><strong> | |
23 | Variable | |
24 | </strong></span></th><th align="left"><span class="bold"><strong> | |
25 | Version 1.10 | |
26 | </strong></span></th><th align="left"><span class="bold"><strong> | |
27 | Version 1.20 | |
28 | </strong></span></th><th align="left"><span class="bold"><strong> | |
29 | Version 1.30 | |
30 | </strong></span></th><th align="left"><span class="bold"><strong> | |
31 | Version 1.40 | |
32 | </strong></span></th><th align="left"><span class="bold"><strong> | |
33 | Version 1.50 | |
34 | </strong></span></th><th align="left"><span class="bold"><strong> | |
35 | Version 3.30 | |
36 | </strong></span></th><th align="left"><span class="bold"><strong> | |
37 | Version 4.00 | |
38 | </strong></span></th><th align="left"><span class="bold"><strong> | |
39 | Version 4.10 | |
40 | </strong></span></th></tr><tr><th align="left"> | |
41 | gl_PrimitiveID | |
42 | </th><th align="center"> | |
43 | <span class="emphasis"><em>Y</em></span> | |
44 | </th><th align="center"> | |
45 | <span class="emphasis"><em>Y</em></span> | |
46 | </th><th align="center"> | |
47 | <span class="emphasis"><em>Y</em></span> | |
48 | </th><th align="center"> | |
49 | <span class="emphasis"><em>Y</em></span> | |
50 | </th><th align="center"> | |
51 | <span class="emphasis"><em>Y</em></span> | |
52 | </th><th align="center"> | |
53 | <span class="emphasis"><em>Y</em></span> | |
54 | </th><th align="center"> | |
55 | <span class="emphasis"><em>Y</em></span> | |
56 | </th><th align="center"> | |
57 | <span class="emphasis"><em>Y</em></span> | |
58 | </th></tr></thead></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p> | |
59 | <a href="gl_InstanceID.xml"><span class="citerefentry"><span class="refentrytitle">gl_InstanceID</span></span></a>, | |
60 | <a href="gl_VertexID.xml"><span class="citerefentry"><span class="refentrytitle">gl_VertexID</span></span></a>, | |
61 | <a href="gl_PrimitiveIDIn.xml"><span class="citerefentry"><span class="refentrytitle">gl_PrimitiveIDIn</span></span></a> | |
62 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> | |
63 | Copyright <span class="trademark"></span>© 2011 Khronos Group. | |
64 | This material may be distributed subject to the terms and conditions set forth in | |
65 | the Open Publication License, v 1.0, 8 June 1999. | |
66 | <a href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>. | |
67 | </p></div></div></body></html> |