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<!DOCTYPE refentry [ <!ENTITY % mathent SYSTEM "math.ent"> %mathent; ]>
<!-- Converted by db4-upgrade version 1.1 -->
<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glViewportArray">
<info>
<copyright>
<year>2010-2014</year>
<holder>Khronos Group</holder>
</copyright>
</info>
<refmeta>
<refentrytitle>glViewportArray</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glViewportArray</refname>
<refpurpose>set multiple viewports</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glViewportArrayv</function></funcdef>
<paramdef>GLuint <parameter>first</parameter></paramdef>
<paramdef>GLsizei <parameter>count</parameter></paramdef>
<paramdef>const GLfloat *<parameter>v</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 xml:id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>first</parameter></term>
<listitem>
<para>
Specify the first viewport to set.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>count</parameter></term>
<listitem>
<para>
Specify the number of viewports to set.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>v</parameter></term>
<listitem>
<para>
Specify the address of an array containing the viewport parameters.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 xml:id="description"><title>Description</title>
<para>
<function>glViewportArrayv</function> specifies the parameters for multiple viewports
simulataneously. <parameter>first</parameter> specifies the index of the first viewport
to modify and <parameter>count</parameter> specifies the number of viewports to modify.
<parameter>first</parameter> must be less than the value of <constant>GL_MAX_VIEWPORTS</constant>,
and <parameter>first</parameter> + <parameter>count</parameter> must be less than or equal to
the value of <constant>GL_MAX_VIEWPORTS</constant>. Viewports whose indices lie outside
the range [<parameter>first</parameter>, <parameter>first</parameter> + <parameter>count</parameter>)
are not modified. <parameter>v</parameter> contains the address of an array of floating
point values specifying the
left (<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation>),
bottom (<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation>),
width (<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">w</mml:mi></mml:math></inlineequation>),
and height (<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">h</mml:mi></mml:math></inlineequation>)
of each viewport, in that order. <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation>
and <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation> give
the location of the viewport's lower left corner, and
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">w</mml:mi></mml:math></inlineequation>
and <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">h</mml:mi></mml:math></inlineequation>
give the width and height of the viewport, respectively.
The viewport specifies the affine transformation of
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation>
and
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation>
from
normalized device coordinates to window coordinates.
Let
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: (x sub nd, y sub nd): -->
<mml:mfenced open="(" close=")">
<mml:msub><mml:mi mathvariant="italic">x</mml:mi>
<mml:mi mathvariant="italic">nd</mml:mi>
</mml:msub>
<mml:msub><mml:mi mathvariant="italic">y</mml:mi>
<mml:mi mathvariant="italic">nd</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math></inlineequation>
be normalized device coordinates.
Then the window coordinates
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: (x sub w, y sub w): -->
<mml:mfenced open="(" close=")">
<mml:msub><mml:mi mathvariant="italic">x</mml:mi>
<mml:mi mathvariant="italic">w</mml:mi>
</mml:msub>
<mml:msub><mml:mi mathvariant="italic">y</mml:mi>
<mml:mi mathvariant="italic">w</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math></inlineequation>
are computed as follows:
</para>
<para>
<informalequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: x sub w = ( x sub nd + 1 ) left ( width over 2 right ) + x: -->
<mml:mrow>
<mml:msub><mml:mi mathvariant="italic">x</mml:mi>
<mml:mi mathvariant="italic">w</mml:mi>
</mml:msub>
<mml:mo>=</mml:mo>
<mml:mrow>
<mml:mfenced open="(" close=")">
<mml:mrow>
<mml:msub><mml:mi mathvariant="italic">x</mml:mi>
<mml:mi mathvariant="italic">nd</mml:mi>
</mml:msub>
<mml:mo>+</mml:mo>
<mml:mn>1</mml:mn>
</mml:mrow>
</mml:mfenced>
<mml:mo>⁢</mml:mo>
<mml:mfenced open="(" close=")">
<mml:mfrac>
<mml:mi mathvariant="italic">width</mml:mi>
<mml:mn>2</mml:mn>
</mml:mfrac>
</mml:mfenced>
<mml:mo>+</mml:mo>
<mml:mi mathvariant="italic">x</mml:mi>
</mml:mrow>
</mml:mrow>
</mml:math></informalequation>
</para>
<para>
<informalequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: y sub w = ( y sub nd + 1 ) left ( height over 2 right ) + y: -->
<mml:mrow>
<mml:msub><mml:mi mathvariant="italic">y</mml:mi>
<mml:mi mathvariant="italic">w</mml:mi>
</mml:msub>
<mml:mo>=</mml:mo>
<mml:mrow>
<mml:mfenced open="(" close=")">
<mml:mrow>
<mml:msub><mml:mi mathvariant="italic">y</mml:mi>
<mml:mi mathvariant="italic">nd</mml:mi>
</mml:msub>
<mml:mo>+</mml:mo>
<mml:mn>1</mml:mn>
</mml:mrow>
</mml:mfenced>
<mml:mo>⁢</mml:mo>
<mml:mfenced open="(" close=")">
<mml:mfrac>
<mml:mi mathvariant="italic">height</mml:mi>
<mml:mn>2</mml:mn>
</mml:mfrac>
</mml:mfenced>
<mml:mo>+</mml:mo>
<mml:mi mathvariant="italic">y</mml:mi>
</mml:mrow>
</mml:mrow>
</mml:math></informalequation>
</para>
<para>
The location of the viewport's bottom left corner, given by
(<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation>, <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation>)
is clamped to be within the implementaiton-dependent viewport bounds range.
The viewport bounds range [<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">min</mml:mi></mml:math></inlineequation>, <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">max</mml:mi></mml:math></inlineequation>]
can be determined by calling <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument
<constant>GL_VIEWPORT_BOUNDS_RANGE</constant>.
Viewport width and height are silently clamped
to a range that depends on the implementation.
To query this range, call <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument
<constant>GL_MAX_VIEWPORT_DIMS</constant>.
</para>
<para>
The precision with which the GL interprets the floating point viewport bounds is implementation-dependent
and may be determined by querying the impementation-defined constant <constant>GL_VIEWPORT_SUBPIXEL_BITS</constant>.
</para>
</refsect1>
<refsect1 xml: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>
<para>
<constant>GL_INVALID_VALUE</constant> is generated if either <parameter>width</parameter> or <parameter>height</parameter> is negative.
</para>
</refsect1>
<refsect1 xml:id="associatedgets"><title>Associated Gets</title>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_VIEWPORT</constant>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MAX_VIEWPORT_DIMS</constant>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_VIEWPORT_BOUNDS_RANGE</constant>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_VIEWPORT_SUBPIXEL_BITS</constant>
</para>
</refsect1>
<refsect1 xml:id="versions"><title>Version Support</title>
<informaltable>
<tgroup cols="13" align="left">
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apifunchead.xml" xpointer="xpointer(/*/*)"/>
<tbody>
<row>
<entry><function>glViewportArrayv</function></entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='41']/*)"/>
</row>
</tbody>
</tgroup>
</informaltable>
</refsect1>
<refsect1 xml:id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>glDepthRange</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glViewport</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glViewportIndexed</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 xml:id="Copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"/> 2010-2014 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.
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://opencontent.org/openpub/">http://opencontent.org/openpub/</link>.
</para>
</refsect1>
</refentry>
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