upstream-doc/man4/xhtml/glSampleCoverage.xml

   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>glSampleCoverage - 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="glSampleCoverage"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glSampleCoverage — specify multisample coverage parameters</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">glSampleCoverage</b>(</code></td><td>GLfloat  </td><td><var class="pdparam">value</var>, </td></tr><tr><td> </td><td>GLboolean  </td><td><var class="pdparam">invert</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>value</code></em></span></dt><dd><p>
   5                     Specify a single floating-point sample coverage value.  The value is
   6                     clamped to the range
   7                     <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
   8
   9                         <mml:mfenced open="[" close="]">
  10                             <mml:mn>0</mml:mn>
  11                             <mml:mn>1</mml:mn>
  12                         </mml:mfenced>
  13                     </mml:math>.
  14                     The initial value is 1.0.
  15                 </p></dd><dt><span class="term"><em class="parameter"><code>invert</code></em></span></dt><dd><p>
  16                     Specify a single boolean value representing if the coverage masks should be
  17                     inverted.  <code class="constant">GL_TRUE</code> and <code class="constant">GL_FALSE</code> are accepted.  The initial value
  18                     is <code class="constant">GL_FALSE</code>.
  19                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  20             Multisampling samples a pixel multiple times at various
  21             implementation-dependent subpixel locations to generate antialiasing
  22             effects.  Multisampling transparently antialiases points, lines, polygons,
  23             and images if it is enabled.
  24         </p><p>
  25             <em class="parameter"><code>value</code></em> is used in constructing a temporary mask used in determining which
  26             samples will be used in resolving the final fragment color.  This mask is
  27             bitwise-anded with the coverage mask generated from the multisampling
  28             computation.  If the <em class="parameter"><code>invert</code></em> flag is set, the temporary mask is inverted
  29             (all bits flipped) and then the bitwise-and is computed.
  30         </p><p>
  31             If an implementation does not have any multisample buffers available, or
  32             multisampling is disabled, rasterization occurs with only a single sample
  33             computing a pixel's final RGB color.
  34         </p><p>
  35             Provided an implementation supports multisample buffers, and multisampling
  36             is enabled, then a pixel's final color is generated by combining several
  37             samples per pixel.  Each sample contains color, depth, and stencil
  38             information, allowing those operations to be performed on each sample.
  39         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
  40             The type of the <em class="parameter"><code>value</code></em> parameter was
  41             changed from GLclampf to GLfloat. This change is transparent
  42             to user code and is described in detail on the
  43             <a href="removedTypes.xml"><span class="citerefentry"><span class="refentrytitle">removedTypes</span></span></a>
  44             page.
  45         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
  46             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_SAMPLE_COVERAGE_VALUE</code>
  47         </p><p>
  48             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_SAMPLE_COVERAGE_INVERT</code>
  49         </p><p>
  50             <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MULTISAMPLE</code>
  51         </p><p>
  52             <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_SAMPLE_ALPHA_TO_COVERAGE</code>
  53         </p><p>
  54             <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_SAMPLE_ALPHA_TO_ONE</code>
  55         </p><p>
  56             <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_SAMPLE_COVERAGE</code>
  57         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
  58             <a href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>,
  59             <a href="removedTypes.xml"><span class="citerefentry"><span class="refentrytitle">removedTypes</span></span></a>
  60         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
  61             Copyright <span class="trademark"></span>© 1991-2006
  62             Silicon Graphics, Inc. This document is licensed under the SGI
  63             Free Software B License. For details, see
  64             <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
  65         </p></div></div></body></html>