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><head><title>glDepthFunc</title><link rel="stylesheet" href="style.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.59.1"/><link rel="home" href="index.xml" title="PyOpenGL 2.0.1.07 Man Pages"/><link rel="up" href="reference-GL.xml" title="GL"/><link rel="previous" href="glDeleteTextures.3G.xml" title="glDeleteTextures"/><link rel="next" href="glDepthMask.3G.xml" title="glDepthMask"/></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">glDepthFunc</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="glDeleteTextures.3G.xml">Prev</a></td><th width="60%" align="center">GL</th><td width="20%" align="right"><a accesskey="n" href="glDepthMask.3G.xml">Next</a></td></tr></table><hr/></div><div class="refentry" lang="en"><a name="glDepthFunc.3G"/><div class="titlepage"/><div class="refnamediv"><a name="glDepthFunc.3G-name"/><h2>Name</h2><p>glDepthFunc — specify the value used for depth buffer comparisons</p></div><div class="refsynopsisdiv"><a name="glDepthFunc.3G-c_spec"/><h2>C Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code>void<tt>glDepthFunc</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code>GLenum<i><tt>func</tt></i>);</code></td></tr></table></div><div class="refsynopsisdiv"><a name="glDepthFunc.3G-python_spec"/><h2>Python Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code><tt>glDepthFunc</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code><i><tt>func</tt></i>) →<tt>None</tt></code></td></tr></table></div><div class="refsect1" lang="en"><a name="glDepthFunc.3G-parameters"/><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><i><tt>func</tt></i></span></dt><dd>
Specifies the depth comparison function. Symbolic constants <tt>GL_NEVER</tt>,
<tt>GL_LESS</tt>, <tt>GL_EQUAL</tt>, <tt>GL_LEQUAL</tt>,
<tt>GL_GREATER</tt>, <tt>GL_NOTEQUAL</tt>, <tt>GL_GEQUAL</tt>, and
<tt>GL_ALWAYS</tt> are accepted. The initial value is <tt>GL_LESS</tt>.
</dd></dl></div></div><div class="refsect1" lang="en"><a name="glDepthFunc.3G-description"/><h2>Description</h2><p>
<tt>glDepthFunc</tt> 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.3G.xml"><tt>glEnable</tt></a> and <a href="glEnable.3G.xml"><tt>glDisable</tt></a> of
<tt>GL_DEPTH_TEST</tt>.)
</p><p>
<i><tt>func</tt></i> 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"><tt>GL_NEVER</tt></span></dt><dd>
Never passes.
</dd><dt><span class="term"><tt>GL_LESS</tt></span></dt><dd>
Passes if the incoming depth value is less than the stored depth value.
</dd><dt><span class="term"><tt>GL_EQUAL</tt></span></dt><dd>
Passes if the incoming depth value is equal to the stored depth value.
</dd><dt><span class="term"><tt>GL_LEQUAL</tt></span></dt><dd>
Passes if the incoming depth value is less than or equal to the stored depth value.
</dd><dt><span class="term"><tt>GL_GREATER</tt></span></dt><dd>
Passes if the incoming depth value is greater than the stored depth value.
</dd><dt><span class="term"><tt>GL_NOTEQUAL</tt></span></dt><dd>
Passes if the incoming depth value is not equal to the stored depth value.
</dd><dt><span class="term"><tt>GL_GEQUAL</tt></span></dt><dd>
Passes if the incoming depth value is greater than or equal to the stored depth value.
</dd><dt><span class="term"><tt>GL_ALWAYS</tt></span></dt><dd>
Always passes.
</dd></dl></div><p>
The initial value of <i><tt>func</tt></i> is <tt>GL_LESS</tt>. Initially, depth testing is disabled.
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.
</p></div><div class="refsect1" lang="en"><a name="glDepthFunc.3G-errors"/><h2>Errors</h2><p>
<tt>GL_INVALID_ENUM</tt> is generated if <i><tt>func</tt></i> is not an accepted value.
</p><p>
<tt>GL_INVALID_OPERATION</tt> is generated if <tt>glDepthFunc</tt> is executed between the
execution of <a href="glBegin.3G.xml"><tt>glBegin</tt></a> and the corresponding execution of <a href="glBegin.3G.xml"><tt>glEnd</tt></a>.
</p></div><div class="refsect1" lang="en"><a name="glDepthFunc.3G-associated_gets"/><h2>Associated Gets</h2><p>
<tt>glGet</tt> with argument <tt>GL_DEPTH_FUNC</tt>
</p><p>
<a href="glIsEnabled.3G.xml"><tt>glIsEnabled</tt></a> with argument <tt>GL_DEPTH_TEST</tt>
</p></div><div class="refsect1" lang="en"><a name="glDepthFunc.3G-see_also"/><h2>See Also</h2><p>
<span class="simplelist"><a href="glDepthRange.3G.xml">glDepthRange</a>, <a href="glEnable.3G.xml">glEnable</a>, <a href="glPolygonOffset.3G.xml">glPolygonOffset</a></span>
</p></div></div><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="glDeleteTextures.3G.xml">Prev</a></td><td width="20%" align="center"><a accesskey="u" href="reference-GL.xml">Up</a></td><td width="40%" align="right"><a accesskey="n" href="glDepthMask.3G.xml">Next</a></td></tr><tr><td width="40%" align="left" valign="top">glDeleteTextures</td><td width="20%" align="center"><a accesskey="h" href="index.xml">Home</a></td><td width="40%" align="right" valign="top">glDepthMask</td></tr></table></div></body></html>
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