upstream-man-pages/man3/xhtml/glDepthRange.xml

   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>glDepthRange</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glDepthRange"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glDepthRange — specify mapping of depth values from normalized device coordinates to window coordinates</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">glDepthRange</b>(</code></td><td>GLclampd  </td><td><var class="pdparam">nearVal</var>, </td></tr><tr><td> </td><td>GLclampd  </td><td><var class="pdparam">farVal</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>nearVal</code></em></span></dt><dd><p>
   5                     Specifies the mapping of the near clipping plane to window coordinates.
   6                     The initial value is 0.
   7                 </p></dd><dt><span class="term"><em class="parameter"><code>farVal</code></em></span></dt><dd><p>
   8                     Specifies the mapping of the far clipping plane to window coordinates.
   9                     The initial value is 1.
  10                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  11             After clipping and division by <span class="emphasis"><em>w</em></span>,
  12             depth coordinates range from
  13             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  14
  15                 <mml:mn>-1</mml:mn>
  16             </mml:math>
  17             to 1,
  18             corresponding to the near and far clipping planes.
  19             <code class="function">glDepthRange</code> specifies a linear mapping of the normalized depth coordinates
  20             in this range to window depth coordinates.
  21             Regardless of the actual depth buffer implementation,
  22             window coordinate depth values are treated as though they range
  23             from 0 through 1 (like color components).
  24             Thus,
  25             the values accepted by <code class="function">glDepthRange</code> are both clamped to this range
  26             before they are accepted.
  27         </p><p>
  28             The setting of (0,1) maps the near plane to 0 and
  29             the far plane to 1.
  30             With this mapping,
  31             the depth buffer range is fully utilized.
  32         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
  33             It is not necessary that <em class="parameter"><code>nearVal</code></em> be less than <em class="parameter"><code>farVal</code></em>.
  34             Reverse mappings such as
  35             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  36
  37                 <mml:mrow>
  38                     <mml:mi mathvariant="italic">nearVal</mml:mi>
  39                     <mml:mo>=</mml:mo>
  40                     <mml:mn>1</mml:mn>
  41                 </mml:mrow>
  42             </mml:math>,
  43             and
  44             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  45
  46                 <mml:mrow>
  47                     <mml:mi mathvariant="italic">farVal</mml:mi>
  48                     <mml:mo>=</mml:mo>
  49                     <mml:mn>0</mml:mn>
  50                 </mml:mrow>
  51             </mml:math>
  52             are acceptable.
  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_RANGE</code>
  55         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
  56             <a href="glDepthFunc.xml"><span class="citerefentry"><span class="refentrytitle">glDepthFunc</span></span></a>,
  57             <a href="glPolygonOffset.xml"><span class="citerefentry"><span class="refentrytitle">glPolygonOffset</span></span></a>,
  58             <a href="glViewport.xml"><span class="citerefentry"><span class="refentrytitle">glViewport</span></span></a>
  59         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
  60             Copyright <span class="trademark"></span>© 1991-2006
  61             Silicon Graphics, Inc. This document is licensed under the SGI
  62             Free Software B License. For details, see
  63             <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
  64         </p></div></div></body></html>