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1 | <?xml version="1.0" encoding="UTF-8"?> |
2 | <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd"> | |
4 | <refentry id="glDepthRange"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>1991-2006</year> | |
9 | <holder>Silicon Graphics, Inc.</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>glDepthRange</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>glDepthRange</refname> | |
17 | <refpurpose>specify mapping of depth values from normalized device coordinates to window coordinates</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>glDepthRange</function></funcdef> | |
23 | <paramdef>GLclampd <parameter>nearVal</parameter></paramdef> | |
24 | <paramdef>GLclampd <parameter>farVal</parameter></paramdef> | |
25 | </funcprototype> | |
26 | </funcsynopsis> | |
27 | </refsynopsisdiv> | |
28 | <!-- eqn: ignoring delim $$ --> | |
29 | <refsect1 id="parameters"><title>Parameters</title> | |
30 | <variablelist> | |
31 | <varlistentry> | |
32 | <term><parameter>nearVal</parameter></term> | |
33 | <listitem> | |
34 | <para> | |
35 | Specifies the mapping of the near clipping plane to window coordinates. | |
36 | The initial value is 0. | |
37 | </para> | |
38 | </listitem> | |
39 | </varlistentry> | |
40 | <varlistentry> | |
41 | <term><parameter>farVal</parameter></term> | |
42 | <listitem> | |
43 | <para> | |
44 | Specifies the mapping of the far clipping plane to window coordinates. | |
45 | The initial value is 1. | |
46 | </para> | |
47 | </listitem> | |
48 | </varlistentry> | |
49 | </variablelist> | |
50 | </refsect1> | |
51 | <refsect1 id="description"><title>Description</title> | |
52 | <para> | |
53 | After clipping and division by <emphasis>w</emphasis>, | |
54 | depth coordinates range from | |
55 | <inlineequation><mml:math> | |
56 | <!-- eqn: -1:--> | |
57 | <mml:mn>-1</mml:mn> | |
58 | </mml:math></inlineequation> | |
59 | to 1, | |
60 | corresponding to the near and far clipping planes. | |
61 | <function>glDepthRange</function> specifies a linear mapping of the normalized depth coordinates | |
62 | in this range to window depth coordinates. | |
63 | Regardless of the actual depth buffer implementation, | |
64 | window coordinate depth values are treated as though they range | |
65 | from 0 through 1 (like color components). | |
66 | Thus, | |
67 | the values accepted by <function>glDepthRange</function> are both clamped to this range | |
68 | before they are accepted. | |
69 | </para> | |
70 | <para> | |
71 | The setting of (0,1) maps the near plane to 0 and | |
72 | the far plane to 1. | |
73 | With this mapping, | |
74 | the depth buffer range is fully utilized. | |
75 | </para> | |
76 | </refsect1> | |
77 | <refsect1 id="notes"><title>Notes</title> | |
78 | <para> | |
79 | It is not necessary that <parameter>nearVal</parameter> be less than <parameter>farVal</parameter>. | |
80 | Reverse mappings such as | |
81 | <inlineequation><mml:math> | |
82 | <!-- eqn: nearVal = 1:--> | |
83 | <mml:mrow> | |
84 | <mml:mi mathvariant="italic">nearVal</mml:mi> | |
85 | <mml:mo>=</mml:mo> | |
86 | <mml:mn>1</mml:mn> | |
87 | </mml:mrow> | |
88 | </mml:math></inlineequation>, | |
89 | and | |
90 | <inlineequation><mml:math> | |
91 | <!-- eqn: farVal = 0:--> | |
92 | <mml:mrow> | |
93 | <mml:mi mathvariant="italic">farVal</mml:mi> | |
94 | <mml:mo>=</mml:mo> | |
95 | <mml:mn>0</mml:mn> | |
96 | </mml:mrow> | |
97 | </mml:math></inlineequation> | |
98 | are acceptable. | |
99 | </para> | |
100 | </refsect1> | |
101 | <refsect1 id="errors"><title>Errors</title> | |
102 | <para> | |
103 | <constant>GL_INVALID_OPERATION</constant> is generated if <function>glDepthRange</function> | |
104 | is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> | |
105 | and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>. | |
106 | </para> | |
107 | </refsect1> | |
108 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
109 | <para> | |
110 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_DEPTH_RANGE</constant> | |
111 | </para> | |
112 | </refsect1> | |
113 | <refsect1 id="seealso"><title>See Also</title> | |
114 | <para> | |
115 | <citerefentry><refentrytitle>glDepthFunc</refentrytitle></citerefentry>, | |
116 | <citerefentry><refentrytitle>glPolygonOffset</refentrytitle></citerefentry>, | |
117 | <citerefentry><refentrytitle>glViewport</refentrytitle></citerefentry> | |
118 | </para> | |
119 | </refsect1> | |
120 | <refsect1 id="Copyright"><title>Copyright</title> | |
121 | <para> | |
122 | Copyright <trademark class="copyright"></trademark> 1991-2006 | |
123 | Silicon Graphics, Inc. This document is licensed under the SGI | |
124 | Free Software B License. For details, see | |
125 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. | |
126 | </para> | |
127 | </refsect1> | |
128 | </refentry> |