upstream-doc/man4/xhtml/glBeginTransformFeedback.xml

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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 - OpenGL 4 Reference Pages</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><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"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glBeginTransformFeedback</b>(</code></td><td>GLenum  </td><td><var class="pdparam">primitiveMode</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><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"><h2>C Specification</h2><div class="funcsynopsis"><p><code class="funcdef">void <b class="fsfunc">glEndTransformFeedback</b>(</code><var class="pdparam">void</var><code>)</code>;</p></div></div><div class="refsect1" lang="en" xml:lang="en"><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 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 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" lang="en" xml:lang="en"><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" lang="en" xml:lang="en"><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 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 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" lang="en" xml:lang="en"><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 href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
  83         </p></div></div></body></html>