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<?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="glDepthRangeArray">
<refentryinfo>
<copyright>
<year>2010-2013</year>
<holder>Khronos Group</holder>
</copyright>
</refentryinfo>
<refmeta>
<refentrytitle>glDepthRangeArray</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glDepthRangeArray</refname>
<refpurpose>specify mapping of depth values from normalized device coordinates to window coordinates for a specified set of viewports</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glDepthRangeArrayv</function></funcdef>
<paramdef>GLuint <parameter>first</parameter></paramdef>
<paramdef>GLsizei <parameter>count</parameter></paramdef>
<paramdef>const GLdouble *<parameter>v</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>first</parameter></term>
<listitem>
<para>
Specifies the index of the first viewport whose depth range to update.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>count</parameter></term>
<listitem>
<para>
Specifies the number of viewports whose depth range to update.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>v</parameter></term>
<listitem>
<para>
Specifies the address of an array containing the near and far values for the
depth range of each modified viewport.
</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.
Each viewport has an independent depth range specified as 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).
<function>glDepthRangeArray</function> specifies a linear mapping of the normalized depth coordinates
in this range to window depth coordinates for each viewport in the range [<parameter>first</parameter>,
<parameter>first</parameter> + <parameter>count</parameter>).
Thus,
the values accepted by <function>glDepthRangeArray</function> are both clamped to this range
before they are accepted.
</para>
<para>
The <parameter>first</parameter> parameter specifies the index of the first viewport whose depth
range to modify and must be less than the value of <constant>GL_MAX_VIEWPORTS</constant>.
<parameter>count</parameter> specifies the number of viewports whose depth range to modify.
<parameter>first</parameter> + <parameter>count</parameter> must be less than or equal to
the value of <constant>GL_MAX_VIEWPORTS</constant>. <parameter>v</parameter> specifies the address of an
array of pairs of double precision floating point values representing the near and far values of the
depth range for each viewport, in that order.
</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 the near plane distance be less than the far plane distance.
Reverse mappings such as
<inlineequation><mml:math>
<!-- eqn: nearVal = 1: -->
<mml:mrow>
<mml:mi mathvariant="italic">near</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">far</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>v</parameter> parameter was
changed from GLclampd to GLdouble. This change is
transparent to user code and is described in detail on the
<citerefentry><refentrytitle>removedTypes</refentrytitle></citerefentry>
page.
</para>
</refsect1>
<refsect1 id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_VALUE</constant> is generated if <parameter>first</parameter> is greater than or equal to
the value of <constant>GL_MAX_VIEWPORTS</constant>.
</para>
<para>
<constant>GL_INVALID_VALUE</constant> is generated if <parameter>first</parameter> + <parameter>count</parameter>
is greater than or equal to the value of <constant>GL_MAX_VIEWPORTS</constant>.
</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>glDepthRange</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDepthRangeIndexed</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glPolygonOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glViewportArray</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> 2010-2013 Khronos Group.
This material may be distributed subject to the terms and conditions set forth in
the Open Publication License, v 1.0, 8 June 1999.
<ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
</para>
</refsect1>
</refentry>
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