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glGetTexGen.xml
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glGetTexGen.xml
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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="glGetTexGen">
<refmeta>
<refmetainfo>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
</refmetainfo>
<refentrytitle>glGetTexGen</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glGetTexGen</refname>
<refpurpose>return texture coordinate generation parameters</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glGetTexGendv</function></funcdef>
<paramdef>GLenum <parameter>coord</parameter></paramdef>
<paramdef>GLenum <parameter>pname</parameter></paramdef>
<paramdef>GLdouble * <parameter>params</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glGetTexGenfv</function></funcdef>
<paramdef>GLenum <parameter>coord</parameter></paramdef>
<paramdef>GLenum <parameter>pname</parameter></paramdef>
<paramdef>GLfloat * <parameter>params</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glGetTexGeniv</function></funcdef>
<paramdef>GLenum <parameter>coord</parameter></paramdef>
<paramdef>GLenum <parameter>pname</parameter></paramdef>
<paramdef>GLint * <parameter>params</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<!-- eqn: ignoring delim $$ -->
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>coord</parameter></term>
<listitem>
<para>
Specifies a texture coordinate.
Must be
<constant>GL_S</constant>,
<constant>GL_T</constant>,
<constant>GL_R</constant>, or
<constant>GL_Q</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>pname</parameter></term>
<listitem>
<para>
Specifies the symbolic name of the value(s) to be returned.
Must be either <constant>GL_TEXTURE_GEN_MODE</constant>
or the name of one of the texture generation plane equations:
<constant>GL_OBJECT_PLANE</constant> or <constant>GL_EYE_PLANE</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>params</parameter></term>
<listitem>
<para>
Returns the requested data.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para>
<function>glGetTexGen</function> returns in <parameter>params</parameter> selected parameters of a texture coordinate
generation function that was specified using <citerefentry><refentrytitle>glTexGen</refentrytitle></citerefentry>.
<parameter>coord</parameter> names one of the (<emphasis>s</emphasis>, <emphasis>t</emphasis>, <emphasis>r</emphasis>, <emphasis>q</emphasis>)
texture coordinates,
using the symbolic constant
<constant>GL_S</constant>,
<constant>GL_T</constant>,
<constant>GL_R</constant>, or
<constant>GL_Q</constant>.
</para>
<para>
<parameter>pname</parameter> specifies one of three symbolic names:
</para>
<variablelist>
<varlistentry>
<term><constant>GL_TEXTURE_GEN_MODE</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns the single-valued texture generation function,
a symbolic constant. The initial value is <constant>GL_EYE_LINEAR</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_OBJECT_PLANE</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns the four plane equation coefficients that specify
object linear-coordinate generation.
Integer values, when requested,
are mapped directly from the internal floating-point representation.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_EYE_PLANE</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns the four plane equation coefficients that specify
eye linear-coordinate generation.
Integer values,
when requested,
are mapped directly from the internal floating-point representation.
The returned values are those maintained in eye coordinates.
They are not equal to the values specified using <citerefentry><refentrytitle>glTexGen</refentrytitle></citerefentry>,
unless the modelview matrix was identity when <citerefentry><refentrytitle>glTexGen</refentrytitle></citerefentry> was called.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para>
If an error is generated,
no change is made to the contents of <parameter>params</parameter>.
</para>
<para>
For OpenGL versions 1.3 and greater, or when the <code>ARB_multitexture</code> extension is supported, <function>glGetTexGen</function> returns
the texture coordinate generation parameters for the active texture unit.
</para>
</refsect1>
<refsect1 id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_ENUM</constant> is generated if <parameter>coord</parameter> or <parameter>pname</parameter> is not an
accepted value.
</para>
<para>
<constant>GL_INVALID_OPERATION</constant> is generated if <function>glGetTexGen</function>
is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glTexGen</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>