upstream-man-pages/man2/xhtml/glSampleCoverage.xml

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd">
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   3 <?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" /><title>glSampleCoverage</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></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>GLclampf  </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>
   4                     Specify a single floating-point sample coverage value.  The value is
   5                     clamped to the range
   6                     <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
   7
   8                         <mml:mfenced open="[" close="]">
   9                             <mml:mn>0</mml:mn>
  10                             <mml:mn>1</mml:mn>
  11                         </mml:mfenced>
  12                     </mml:math>.
  13                     The initial value is 1.0.
  14                 </p></dd><dt><span class="term"><em class="parameter"><code>invert</code></em></span></dt><dd><p>
  15                     Specify a single boolean value representing if the coverage masks should be
  16                     inverted.  <code class="constant">GL_TRUE</code> and <code class="constant">GL_FALSE</code> are accepted.  The initial value
  17                     is <code class="constant">GL_FALSE</code>.
  18                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  19             Multisampling samples a pixel multiple times at various
  20             implementation-dependent subpixel locations to generate antialiasing
  21             effects.  Multisampling transparently antialiases points, lines, polygons,
  22             bitmaps, and images if it is enabled.
  23         </p><p>
  24             <em class="parameter"><code>value</code></em> is used in constructing a temporary mask used in determining which
  25             samples will be used in resolving the final fragment color.  This mask is
  26             bitwise-anded with the coverage mask generated from the multisampling
  27             computation.  If the <em class="parameter"><code>invert</code></em> flag is set, the temporary mask is inverted
  28             (all bits flipped) and then the bitwise-and is computed.
  29         </p><p>
  30             If an implementation does not have any multisample buffers available, or
  31             multisampling is disabled, rasterization occurs with only a single sample
  32             computing a pixel's final RGB color.
  33         </p><p>
  34             Provided an implementation supports multisample buffers, and multisampling
  35             is enabled, then a pixel's final color is generated by combining several
  36             samples per pixel.  Each sample contains color, depth, and stencil
  37             information, allowing those operations to be performed on each sample.
  38         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
  39             <code class="function">glSampleCoverage</code> is available only if the GL version is 1.3 or greater.
  40         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
  41             <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glSampleCoverage</code> is executed between the
  42             execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> and the corresponding execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
  43         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
  44             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_SAMPLE_COVERAGE_VALUE</code>
  45         </p><p>
  46             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_SAMPLE_COVERAGE_INVERT</code>
  47         </p><p>
  48             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MULTISAMPLE</code>
  49         </p><p>
  50             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_SAMPLE_ALPHA_TO_COVERAGE</code>
  51         </p><p>
  52             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_SAMPLE_ALPHA_TO_ONE</code>
  53         </p><p>
  54             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_SAMPLE_COVERAGE</code>
  55         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
  56             <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>,
  57             <a class="citerefentry" href="glPushAttrib.xml"><span class="citerefentry"><span class="refentrytitle">glPushAttrib</span></span></a>
  58         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
  59             Copyright <span class="trademark"></span>© 1991-2006
  60             Silicon Graphics, Inc. This document is licensed under the SGI
  61             Free Software B License. For details, see
  62             <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
  63         </p></div></div></body></html>