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+<?xml version="1.0" encoding="UTF-8"?>
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+<?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>glDepthFunc</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glDepthFunc"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glDepthFunc — specify the value used for depth buffer comparisons</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><p><code class="funcdef">void <b class="fsfunc">glDepthFunc</b>(</code>GLenum <var class="pdparam">func</var><code>)</code>;</p></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>func</code></em></span></dt><dd><p>
+ Specifies the depth comparison function.
+ Symbolic constants
+ <code class="constant">GL_NEVER</code>,
+ <code class="constant">GL_LESS</code>,
+ <code class="constant">GL_EQUAL</code>,
+ <code class="constant">GL_LEQUAL</code>,
+ <code class="constant">GL_GREATER</code>,
+ <code class="constant">GL_NOTEQUAL</code>,
+ <code class="constant">GL_GEQUAL</code>, and
+ <code class="constant">GL_ALWAYS</code> are accepted.
+ The initial value is <code class="constant">GL_LESS</code>.
+ </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
+ <code class="function">glDepthFunc</code> specifies the function used to compare each incoming pixel depth value
+ with the depth value present in the depth buffer.
+ The comparison is performed only if depth testing is enabled.
+ (See <a href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a> and <a href="glDisable.xml"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a> of <code class="constant">GL_DEPTH_TEST</code>.)
+ </p><p>
+ <em class="parameter"><code>func</code></em> specifies the conditions under which the pixel will be drawn.
+ The comparison functions are as follows:
+ </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_NEVER</code></span></dt><dd><p>
+ Never passes.
+ </p></dd><dt><span class="term"><code class="constant">GL_LESS</code></span></dt><dd><p>
+ Passes if the incoming depth value is less than the stored depth value.
+ </p></dd><dt><span class="term"><code class="constant">GL_EQUAL</code></span></dt><dd><p>
+ Passes if the incoming depth value is equal to the stored depth value.
+ </p></dd><dt><span class="term"><code class="constant">GL_LEQUAL</code></span></dt><dd><p>
+ Passes if the incoming depth value is less than or equal to
+ the stored depth value.
+ </p></dd><dt><span class="term"><code class="constant">GL_GREATER</code></span></dt><dd><p>
+ Passes if the incoming depth value is greater than the stored depth value.
+ </p></dd><dt><span class="term"><code class="constant">GL_NOTEQUAL</code></span></dt><dd><p>
+ Passes if the incoming depth value is not equal to the stored depth value.
+ </p></dd><dt><span class="term"><code class="constant">GL_GEQUAL</code></span></dt><dd><p>
+ Passes if the incoming depth value is greater than or equal to
+ the stored depth value.
+ </p></dd><dt><span class="term"><code class="constant">GL_ALWAYS</code></span></dt><dd><p>
+ Always passes.
+ </p></dd></dl></div><p>
+ The initial value of <em class="parameter"><code>func</code></em> is <code class="constant">GL_LESS</code>.
+ Initially, depth testing is disabled. If depth testing is disabled or if no
+ depth buffer exists, it is as if the depth test always passes.
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
+ Even if the depth buffer exists and the depth mask is non-zero, the
+ depth buffer is not updated if the depth test is disabled. In order to
+ unconditionally write to the depth buffer, the depth test should be enabled
+ and set to <code class="constant">GL_ALWAYS</code>.
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
+ <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>func</code></em> is not an accepted value.
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
+ <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_DEPTH_FUNC</code>
+ </p><p>
+ <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_DEPTH_TEST</code>
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
+ <a href="glDepthRange.xml"><span class="citerefentry"><span class="refentrytitle">glDepthRange</span></span></a>,
+ <a href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>,
+ <a href="glPolygonOffset.xml"><span class="citerefentry"><span class="refentrytitle">glPolygonOffset</span></span></a>
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
+ Copyright <span class="trademark"></span>© 1991-2006
+ Silicon Graphics, Inc. This document is licensed under the SGI
+ Free Software B License. For details, see
+ <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
+ </p></div></div></body></html>
HCoop / clinton / guile-figl.git / blobdiff