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1 | <?xml version="1.0" encoding="UTF-8"?> |
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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>glBeginTransformFeedback</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /></head><body><div class="refentry" title="glBeginTransformFeedback"><a id="glBeginTransformFeedback"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glBeginTransformFeedback — start transform feedback operation</p></div><div class="refsynopsisdiv" title="C Specification"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">glBeginTransformFeedback</b>(</code></td><td>GLenum <var class="pdparam">primitiveMode</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Parameters"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>primitiveMode</code></em></span></dt><dd><p> | |
5 | Specify the output type of the primitives that will be recorded into the | |
6 | buffer objects that are bound for transform feedback. | |
7 | </p></dd></dl></div></div><div class="refsynopsisdiv" title="C Specification"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">glEndTransformFeedback</b>(</code></td><td><var class="pdparam">void</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Description"><a id="description"></a><h2>Description</h2><p> | |
8 | Transform feedback mode captures the values of varying variables written by the vertex shader (or, if active, the geometry shader). | |
9 | Transform feedback is said to be active after a call to <code class="function">glBeginTransformFeedback</code> | |
10 | until a subsequent call to <a class="citerefentry" href="glEndTransformFeedback.xml"><span class="citerefentry"><span class="refentrytitle">glEndTransformFeedback</span></span></a>. | |
11 | Transform feedback commands must be paired. | |
12 | </p><p> | |
13 | If no geometry shader is present, while transform feedback is active the <em class="parameter"><code>mode</code></em> parameter to | |
14 | <a class="citerefentry" href="glDrawArrays.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArrays</span></span></a> must match those specified | |
15 | in the following table: | |
16 | </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="left" /></colgroup><thead><tr><th align="left"><span class="bold"><strong> | |
17 | Transform Feedback <em class="parameter"><code>primitiveMode</code></em> | |
18 | </strong></span></th><th align="left"><span class="bold"><strong> | |
19 | Allowed Render Primitive <em class="parameter"><code>modes</code></em> | |
20 | </strong></span></th></tr></thead><tbody><tr><td align="left"> | |
21 | <code class="constant">GL_POINTS</code> | |
22 | </td><td align="left"> | |
23 | <code class="constant">GL_POINTS</code> | |
24 | </td></tr><tr><td align="left"> | |
25 | <code class="constant">GL_LINES</code> | |
26 | </td><td align="left"> | |
27 | <code class="constant">GL_LINES</code>, <code class="constant">GL_LINE_LOOP</code>, <code class="constant">GL_LINE_STRIP</code>, | |
28 | <code class="constant">GL_LINES_ADJACENCY</code>, <code class="constant">GL_LINE_STRIP_ADJACENCY</code> | |
29 | </td></tr><tr><td align="left"> | |
30 | <code class="constant">GL_TRIANGLES</code> | |
31 | </td><td align="left"> | |
32 | <code class="constant">GL_TRIANGLES</code>, <code class="constant">GL_TRIANGLE_STRIP</code>, <code class="constant">GL_TRIANGLE_FAN</code>, | |
33 | <code class="constant">GL_TRIANGLES_ADJACENCY</code>, <code class="constant">GL_TRIANGLE_STRIP_ADJACENCY</code> | |
34 | </td></tr></tbody></table></div><p> | |
35 | If a geometry shader is present, the output primitive type from the geometry shader must match those | |
36 | provided in the following table: | |
37 | </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="left" /></colgroup><thead><tr><th align="left"><span class="bold"><strong> | |
38 | Transform Feedback <em class="parameter"><code>primitiveMode</code></em> | |
39 | </strong></span></th><th align="left"><span class="bold"><strong> | |
40 | Allowed Geometry Shader Output Primitive Type | |
41 | </strong></span></th></tr></thead><tbody><tr><td align="left"> | |
42 | <code class="constant">GL_POINTS</code> | |
43 | </td><td align="left"> | |
44 | <code class="constant">points</code> | |
45 | </td></tr><tr><td align="left"> | |
46 | <code class="constant">GL_LINES</code> | |
47 | </td><td align="left"> | |
48 | <code class="constant">line_strip</code> | |
49 | </td></tr><tr><td align="left"> | |
50 | <code class="constant">GL_TRIANGLES</code> | |
51 | </td><td align="left"> | |
52 | <code class="constant">triangle_strip</code> | |
53 | </td></tr></tbody></table></div><p> | |
54 | </p></div><div class="refsect1" title="Notes"><a id="notes"></a><h2>Notes</h2><p> | |
55 | Geometry shaders, and the <code class="constant">GL_TRIANGLES_ADJACENCY</code>, <code class="constant">GL_TRIANGLE_STRIP_ADJACENCY</code>, | |
56 | <code class="constant">GL_LINES_ADJACENCY</code> and <code class="constant">GL_LINE_STRIP_ADJACENCY</code> primtive modes are available | |
57 | only if the GL version is 3.2 or greater. | |
58 | </p></div><div class="refsect1" title="Errors"><a id="errors"></a><h2>Errors</h2><p> | |
59 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glBeginTransformFeedback</code> is executed | |
60 | while transform feedback is active. | |
61 | </p><p> | |
62 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glEndTransformFeedback</code> is executed | |
63 | while transform feedback is not active. | |
64 | </p><p> | |
65 | <code class="constant">GL_INVALID_OPERATION</code> is generated by <a class="citerefentry" href="glDrawArrays.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArrays</span></span></a> | |
66 | if no geometry shader is present, transform feedback is active and <em class="parameter"><code>mode</code></em> is not one of the allowed modes. | |
67 | </p><p> | |
68 | <code class="constant">GL_INVALID_OPERATION</code> is generated by <a class="citerefentry" href="glDrawArrays.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArrays</span></span></a> | |
69 | if a geometry shader is present, transform feedback is active and the output primitive type of the geometry shader does not | |
70 | match the transform feedback <em class="parameter"><code>primitiveMode</code></em>. | |
71 | </p><p> | |
72 | <code class="constant">GL_INVALID_OPERATION</code> is generated by <code class="function">glEndTransformFeedback</code> if any binding | |
73 | point used in transform feedback mode does not have a buffer object bound. | |
74 | </p><p> | |
75 | <code class="constant">GL_INVALID_OPERATION</code> is generated by <code class="function">glEndTransformFeedback</code> if no binding | |
76 | points would be used, either because no program object is active of because the active program object has specified | |
77 | no varying variables to record. | |
78 | </p></div><div class="refsect1" title="Copyright"><a id="Copyright"></a><h2>Copyright</h2><p> | |
79 | Copyright <span class="trademark"></span>© 2010 Khronos Group. | |
80 | This material may be distributed subject to the terms and conditions set forth in | |
81 | the Open Publication License, v 1.0, 8 June 1999. | |
82 | <a class="ulink" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>. | |
83 | </p></div></div></body></html> |