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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd">
<?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>glViewportArray - OpenGL 4 Reference Pages</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1" /></head><body><div class="refentry"><a id="glViewportArray"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glViewportArray — set multiple viewports</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">void <strong class="fsfunc">glViewportArrayv</strong>(</code></td><td>GLuint <var class="pdparam">first</var>, </td></tr><tr><td> </td><td>GLsizei <var class="pdparam">count</var>, </td></tr><tr><td> </td><td>const GLfloat *<var class="pdparam">v</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>first</code></em></span></dt><dd><p>
Specify the first viewport to set.
</p></dd><dt><span class="term"><em class="parameter"><code>count</code></em></span></dt><dd><p>
Specify the number of viewports to set.
</p></dd><dt><span class="term"><em class="parameter"><code>v</code></em></span></dt><dd><p>
Specify the address of an array containing the viewport parameters.
</p></dd></dl></div></div><div class="refsect1"><a id="description"></a><h2>Description</h2><p>
<code class="function">glViewportArrayv</code> specifies the parameters for multiple viewports
simulataneously. <em class="parameter"><code>first</code></em> specifies the index of the first viewport
to modify and <em class="parameter"><code>count</code></em> specifies the number of viewports to modify.
<em class="parameter"><code>first</code></em> must be less than the value of <code class="constant">GL_MAX_VIEWPORTS</code>,
and <em class="parameter"><code>first</code></em> + <em class="parameter"><code>count</code></em> must be less than or equal to
the value of <code class="constant">GL_MAX_VIEWPORTS</code>. Viewports whose indices lie outside
the range [<em class="parameter"><code>first</code></em>, <em class="parameter"><code>first</code></em> + <em class="parameter"><code>count</code></em>)
are not modified. <em class="parameter"><code>v</code></em> contains the address of an array of floating
point values specifying the
left (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math>),
bottom (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math>),
width (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">w</mml:mi></mml:math>),
and height (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">h</mml:mi></mml:math>)
of each viewport, in that order. <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math>
and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math> give
the location of the viewport's lower left corner, and
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">w</mml:mi></mml:math>
and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">h</mml:mi></mml:math>
give the width and height of the viewport, respectively.
The viewport specifies the affine transformation of
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math>
and
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math>
from
normalized device coordinates to window coordinates.
Let
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<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>
be normalized device coordinates.
Then the window coordinates
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<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>
are computed as follows:
</p><p>
</p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<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></div><p>
</p><p>
</p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<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></div><p>
</p><p>
The location of the viewport's bottom left corner, given by
(<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math>, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math>)
is clamped to be within the implementaiton-dependent viewport bounds range.
The viewport bounds range [<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">min</mml:mi></mml:math>, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">max</mml:mi></mml:math>]
can be determined by calling <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument
<code class="constant">GL_VIEWPORT_BOUNDS_RANGE</code>.
Viewport width and height are silently clamped
to a range that depends on the implementation.
To query this range, call <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument
<code class="constant">GL_MAX_VIEWPORT_DIMS</code>.
</p><p>
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 <code class="constant">GL_VIEWPORT_SUBPIXEL_BITS</code>.
</p></div><div class="refsect1"><a id="errors"></a><h2>Errors</h2><p>
<code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>first</code></em> is greater than or equal to
the value of <code class="constant">GL_MAX_VIEWPORTS</code>.
</p><p>
<code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>first</code></em> + <em class="parameter"><code>count</code></em>
is greater than or equal to the value of <code class="constant">GL_MAX_VIEWPORTS</code>.
</p><p>
<code class="constant">GL_INVALID_VALUE</code> is generated if either <em class="parameter"><code>width</code></em> or <em class="parameter"><code>height</code></em> is negative.
</p></div><div class="refsect1"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
<a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_VIEWPORT</code>
</p><p>
<a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_MAX_VIEWPORT_DIMS</code>
</p><p>
<a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_VIEWPORT_BOUNDS_RANGE</code>
</p><p>
<a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_VIEWPORT_SUBPIXEL_BITS</code>
</p></div><div class="refsect1"><a id="seealso"></a><h2>See Also</h2><p>
<a class="citerefentry" href="glDepthRange.xml"><span class="citerefentry"><span class="refentrytitle">glDepthRange</span></span></a>,
<a class="citerefentry" href="glViewport.xml"><span class="citerefentry"><span class="refentrytitle">glViewport</span></span></a>,
<a class="citerefentry" href="glViewportIndexed.xml"><span class="citerefentry"><span class="refentrytitle">glViewportIndexed</span></span></a>
</p></div><div class="refsect1"><a id="Copyright"></a><h2>Copyright</h2><p>
Copyright <span class="trademark"></span>© 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.
<a class="ulink" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
</p></div></div></body></html>
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