upstream-man-pages/manglsl/xhtml/gl_PointSize.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>gl_PointSize - 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_PointSize"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>gl_PointSize — contains size of rasterized points, in pixels</p></div><div class="refsynopsisdiv"><h2>Declaration</h2><p>
   5             <code class="function">gl_PointSize</code> is a member of the <code class="function">gl_PerVertex</code>
   6             named block:
   7         </p><div class="funcsynopsis"><pre class="programlisting">    out gl_PerVertex {
   8         vec4 gl_Position;
   9         float gl_PointSize;
  10         float gl_ClipDistance[];
  11     };</pre></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  12             In the vertex, tessellation evaluation and geoemtry languages, a single
  13             global instance of the <code class="function">gl_PerVertex</code> named block is available and
  14             its <code class="function">gl_PointSize</code> member is an output that receives the
  15             intended size of the point to be rasterized, in pixels. It may be written at any time
  16             during shader execution. If <code class="constant">GL_PROGRAM_POINT_SIZE</code> is enabled,
  17             <code class="function">gl_PointSize</code> is used to determine the size of rasterized
  18             points, otherwise it is ignored by the rasterization stage.
  19         </p><p>
  20             In the tessellation control language, the <code class="function">gl_PerVertex</code> named block
  21             is used to construct an array, <code class="function">gl_out[]</code>, whose members become
  22             available as inputs to the subsequent tessellation evaluation shader.
  23         </p><p>
  24             The value of <code class="function">gl_PointSize</code> (or the <code class="function">gl_PointSize</code> member of the <code class="function">gl_out[]</code>
  25             array, in the case of the tessellation control shader)
  26             is undefined after the vertex, tessellation control, and tessellation evaluation
  27             shading stages if the corresponding shader executable does
  28             not write to gl_PointSize. It is also undefined after the geometry processing stage if the geometry shader executable calls
  29             <a href="EmitVertex.xml"><span class="citerefentry"><span class="refentrytitle">EmitVertex</span></span></a> without having
  30             written <code class="function">gl_PointSize</code> since the last call to <a href="EmitVertex.xml"><span class="citerefentry"><span class="refentrytitle">EmitVertex</span></span></a>
  31             (or hasn't written it at all).
  32         </p><p>
  33             In the tessellation control, tessellation evaluation and geoemetry languages,
  34             the <code class="function">gl_PerVertex</code> named block is used to construct an array, <code class="function">gl_in[]</code>
  35             of per-vertex or per-control point inputs whose content represents the corresponding
  36             outputs written by the previous stage.
  37          </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" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>Variable</strong></span></th><th align="left"><span class="bold"><strong>Version 1.10</strong></span></th><th align="left"><span class="bold"><strong>Version 1.20</strong></span></th><th align="left"><span class="bold"><strong>Version 1.30</strong></span></th><th align="left"><span class="bold"><strong>Version 1.40</strong></span></th><th align="left"><span class="bold"><strong>Version 1.50</strong></span></th><th align="left"><span class="bold"><strong>Version 3.30</strong></span></th><th align="left"><span class="bold"><strong>Version 4.00</strong></span></th><th align="left"><span class="bold"><strong>Version 4.10</strong></span></th><th align="left"><span class="bold"><strong>Version 4.20</strong></span></th><th align="center"><span class="bold"><strong>Version 4.30</strong></span></th></tr><tr><th align="left">gl_PointSize (vertex shader)</th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th></tr><tr><th align="left">gl_PointSize (geometry shader)</th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th></tr></thead></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
  38             <a href="gl_Position.xml"><span class="citerefentry"><span class="refentrytitle">gl_Position</span></span></a>, <a href="gl_ClipDistance.xml"><span class="citerefentry"><span class="refentrytitle">gl_ClipDistance</span></span></a>
  39         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
  40             Copyright <span class="trademark"></span>© 2011 Khronos Group.
  41             This material may be distributed subject to the terms and conditions set forth in
  42             the Open Publication License, v 1.0, 8 June 1999.
  43             <a href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
  44         </p></div></div></body></html>