Opentk/Source/Bind/Specifications/Docs/glDepthRange.xml
Stefanos A 60f971ffed Updated to the latest gl4 specs and docs
Large code-drop from Khronos upstream.
2013-11-03 12:43:50 +01:00

137 lines
5.8 KiB
XML

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
<refentry id="glDepthRange">
<refentryinfo>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
</refentryinfo>
<refmeta>
<refentrytitle>glDepthRange</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glDepthRange</refname>
<refpurpose>specify mapping of depth values from normalized device coordinates to window coordinates</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glDepthRange</function></funcdef>
<paramdef>GLdouble <parameter>nearVal</parameter></paramdef>
<paramdef>GLdouble <parameter>farVal</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>void <function>glDepthRangef</function></funcdef>
<paramdef>GLfloat <parameter>nearVal</parameter></paramdef>
<paramdef>GLfloat <parameter>farVal</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>nearVal</parameter></term>
<listitem>
<para>
Specifies the mapping of the near clipping plane to window coordinates.
The initial value is 0.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>farVal</parameter></term>
<listitem>
<para>
Specifies the mapping of the far clipping plane to window coordinates.
The initial value is 1.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para>
After clipping and division by <emphasis>w</emphasis>,
depth coordinates range from
<inlineequation><mml:math>
<!-- eqn: -1: -->
<mml:mn>-1</mml:mn>
</mml:math></inlineequation>
to 1,
corresponding to the near and far clipping planes.
<function>glDepthRange</function> specifies a linear mapping of the normalized depth coordinates
in this range to window depth coordinates.
Regardless of the actual depth buffer implementation,
window coordinate depth values are treated as though they range
from 0 through 1 (like color components).
Thus,
the values accepted by <function>glDepthRange</function> are both clamped to this range
before they are accepted.
</para>
<para>
The setting of (0,1) maps the near plane to 0 and
the far plane to 1.
With this mapping,
the depth buffer range is fully utilized.
</para>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para>
It is not necessary that <parameter>nearVal</parameter> be less than <parameter>farVal</parameter>.
Reverse mappings such as
<inlineequation><mml:math>
<!-- eqn: nearVal = 1: -->
<mml:mrow>
<mml:mi mathvariant="italic">nearVal</mml:mi>
<mml:mo>=</mml:mo>
<mml:mn>1</mml:mn>
</mml:mrow>
</mml:math></inlineequation>,
and
<inlineequation><mml:math>
<!-- eqn: farVal = 0: -->
<mml:mrow>
<mml:mi mathvariant="italic">farVal</mml:mi>
<mml:mo>=</mml:mo>
<mml:mn>0</mml:mn>
</mml:mrow>
</mml:math></inlineequation>
are acceptable.
</para>
<para>
The type of the <parameter>nearVal</parameter> and
<parameter>farVal</parameter> parameters was changed from
GLclampf to GLfloat for <function>glDepthRangef</function>
and from GLclampd to GLdouble for
<function>glDepthRange</function>. This change is
transparent to user code and is described in detail on the
<citerefentry><refentrytitle>removedTypes</refentrytitle></citerefentry>
page.
</para>
</refsect1>
<refsect1 id="associatedgets"><title>Associated Gets</title>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_DEPTH_RANGE</constant>
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>glDepthFunc</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glPolygonOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glViewport</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>removedTypes</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 id="Copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"></trademark> 1991-2006
Silicon Graphics, Inc. This document is licensed under the SGI
Free Software B License. For details, see
<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
</para>
</refsect1>
</refentry>