Commit | Line | Data |
---|---|---|
7faf1d71 AW |
1 | <?xml version="1.0" encoding="UTF-8"?> |
2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd"> | |
3 | <!-- saved from url=(0013)about:internet --> | |
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>glDepthFunc - 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="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> | |
5 | Specifies the depth comparison function. | |
6 | Symbolic constants | |
7 | <code class="constant">GL_NEVER</code>, | |
8 | <code class="constant">GL_LESS</code>, | |
9 | <code class="constant">GL_EQUAL</code>, | |
10 | <code class="constant">GL_LEQUAL</code>, | |
11 | <code class="constant">GL_GREATER</code>, | |
12 | <code class="constant">GL_NOTEQUAL</code>, | |
13 | <code class="constant">GL_GEQUAL</code>, and | |
14 | <code class="constant">GL_ALWAYS</code> are accepted. | |
15 | The initial value is <code class="constant">GL_LESS</code>. | |
16 | </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p> | |
17 | <code class="function">glDepthFunc</code> specifies the function used to compare each incoming pixel depth value | |
18 | with the depth value present in the depth buffer. | |
19 | The comparison is performed only if depth testing is enabled. | |
20 | (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>.) | |
21 | </p><p> | |
22 | <em class="parameter"><code>func</code></em> specifies the conditions under which the pixel will be drawn. | |
23 | The comparison functions are as follows: | |
24 | </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_NEVER</code></span></dt><dd><p> | |
25 | Never passes. | |
26 | </p></dd><dt><span class="term"><code class="constant">GL_LESS</code></span></dt><dd><p> | |
27 | Passes if the incoming depth value is less than the stored depth value. | |
28 | </p></dd><dt><span class="term"><code class="constant">GL_EQUAL</code></span></dt><dd><p> | |
29 | Passes if the incoming depth value is equal to the stored depth value. | |
30 | </p></dd><dt><span class="term"><code class="constant">GL_LEQUAL</code></span></dt><dd><p> | |
31 | Passes if the incoming depth value is less than or equal to | |
32 | the stored depth value. | |
33 | </p></dd><dt><span class="term"><code class="constant">GL_GREATER</code></span></dt><dd><p> | |
34 | Passes if the incoming depth value is greater than the stored depth value. | |
35 | </p></dd><dt><span class="term"><code class="constant">GL_NOTEQUAL</code></span></dt><dd><p> | |
36 | Passes if the incoming depth value is not equal to the stored depth value. | |
37 | </p></dd><dt><span class="term"><code class="constant">GL_GEQUAL</code></span></dt><dd><p> | |
38 | Passes if the incoming depth value is greater than or equal to | |
39 | the stored depth value. | |
40 | </p></dd><dt><span class="term"><code class="constant">GL_ALWAYS</code></span></dt><dd><p> | |
41 | Always passes. | |
42 | </p></dd></dl></div><p> | |
43 | The initial value of <em class="parameter"><code>func</code></em> is <code class="constant">GL_LESS</code>. | |
44 | Initially, depth testing is disabled. If depth testing is disabled or if no | |
45 | depth buffer exists, it is as if the depth test always passes. | |
46 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p> | |
47 | Even if the depth buffer exists and the depth mask is non-zero, the | |
48 | depth buffer is not updated if the depth test is disabled. In order to | |
49 | unconditionally write to the depth buffer, the depth test should be enabled | |
50 | and set to <code class="constant">GL_ALWAYS</code>. | |
51 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p> | |
52 | <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>func</code></em> is not an accepted value. | |
53 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p> | |
54 | <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_DEPTH_FUNC</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_DEPTH_TEST</code> | |
57 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p> | |
58 | <a href="glDepthRange.xml"><span class="citerefentry"><span class="refentrytitle">glDepthRange</span></span></a>, | |
59 | <a href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>, | |
60 | <a href="glPolygonOffset.xml"><span class="citerefentry"><span class="refentrytitle">glPolygonOffset</span></span></a> | |
61 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> | |
62 | Copyright <span class="trademark"></span>© 1991-2006 | |
63 | Silicon Graphics, Inc. This document is licensed under the SGI | |
64 | Free Software B License. For details, see | |
65 | <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>. | |
66 | </p></div></div></body></html> |