--- /dev/null
+<?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="glViewport">
+ <refmeta>
+ <refmetainfo>
+ <copyright>
+ <year>1991-2006</year>
+ <holder>Silicon Graphics, Inc.</holder>
+ </copyright>
+ </refmetainfo>
+ <refentrytitle>glViewport</refentrytitle>
+ <manvolnum>3G</manvolnum>
+ </refmeta>
+ <refnamediv>
+ <refname>glViewport</refname>
+ <refpurpose>set the viewport</refpurpose>
+ </refnamediv>
+ <refsynopsisdiv><title>C Specification</title>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>void <function>glViewport</function></funcdef>
+ <paramdef>GLint <parameter>x</parameter></paramdef>
+ <paramdef>GLint <parameter>y</parameter></paramdef>
+ <paramdef>GLsizei <parameter>width</parameter></paramdef>
+ <paramdef>GLsizei <parameter>height</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+ <!-- eqn: ignoring delim $$ -->
+ <refsect1 id="parameters"><title>Parameters</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>x</parameter></term>
+ <term><parameter>y</parameter></term>
+ <listitem>
+ <para>
+ Specify the lower left corner of the viewport rectangle,
+ in pixels. The initial value is (0,0).
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>width</parameter></term>
+ <term><parameter>height</parameter></term>
+ <listitem>
+ <para>
+ Specify the width and height
+ of the viewport.
+ When a GL context is first attached to a window,
+ <parameter>width</parameter> and <parameter>height</parameter> are set to the dimensions of that
+ window.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1 id="description"><title>Description</title>
+ <para>
+ <function>glViewport</function> specifies the affine transformation of
+ <inlineequation><mml:math><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation>
+ and
+ <inlineequation><mml:math><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation>
+ from
+ normalized device coordinates to window coordinates.
+ Let
+ <inlineequation><mml:math>
+ <!-- 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>
+ <!-- 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>
+ <!-- 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>
+ <!-- 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>
+ 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>
+ </refsect1>
+ <refsect1 id="errors"><title>Errors</title>
+ <para>
+ <constant>GL_INVALID_VALUE</constant> is generated if either <parameter>width</parameter> or <parameter>height</parameter> is negative.
+ </para>
+ </refsect1>
+ <refsect1 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>
+ </refsect1>
+ <refsect1 id="seealso"><title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>glDepthRange</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>
HCoop / clinton / guile-figl.git / blobdiff