364 lines
18 KiB
XML
364 lines
18 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
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<refentry id="glGetTexEnv">
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<refmeta>
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<refmetainfo>
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<copyright>
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<year>1991-2006</year>
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<holder>Silicon Graphics, Inc.</holder>
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</copyright>
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</refmetainfo>
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<refentrytitle>glGetTexEnv</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glGetTexEnv</refname>
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<refpurpose>return texture environment parameters</refpurpose>
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</refnamediv>
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<refsynopsisdiv><title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glGetTexEnvfv</function></funcdef>
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<paramdef>GLenum <parameter>target</parameter></paramdef>
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<paramdef>GLenum <parameter>pname</parameter></paramdef>
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<paramdef>GLfloat * <parameter>params</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<para></para>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glGetTexEnviv</function></funcdef>
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<paramdef>GLenum <parameter>target</parameter></paramdef>
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<paramdef>GLenum <parameter>pname</parameter></paramdef>
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<paramdef>GLint * <parameter>params</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1 id="parameters"><title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><parameter>target</parameter></term>
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<listitem>
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<para>
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Specifies a texture environment. May be
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<constant>GL_TEXTURE_ENV</constant>,
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<constant>GL_TEXTURE_FILTER_CONTROL</constant>, or
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<constant>GL_POINT_SPRITE</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>pname</parameter></term>
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<listitem>
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<para>
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Specifies the symbolic name of a texture environment parameter.
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Accepted values are <constant>GL_TEXTURE_ENV_MODE</constant>, <constant>GL_TEXTURE_ENV_COLOR</constant>,
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<constant>GL_TEXTURE_LOD_BIAS</constant>,
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<constant>GL_COMBINE_RGB</constant>,
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<constant>GL_COMBINE_ALPHA</constant>,
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<constant>GL_SRC0_RGB</constant>,
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<constant>GL_SRC1_RGB</constant>,
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<constant>GL_SRC2_RGB</constant>,
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<constant>GL_SRC0_ALPHA</constant>,
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<constant>GL_SRC1_ALPHA</constant>,
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<constant>GL_SRC2_ALPHA</constant>,
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<constant>GL_OPERAND0_RGB</constant>,
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<constant>GL_OPERAND1_RGB</constant>,
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<constant>GL_OPERAND2_RGB</constant>,
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<constant>GL_OPERAND0_ALPHA</constant>,
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<constant>GL_OPERAND1_ALPHA</constant>,
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<constant>GL_OPERAND2_ALPHA</constant>,
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<constant>GL_RGB_SCALE</constant>,
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<constant>GL_ALPHA_SCALE</constant>, or
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<constant>GL_COORD_REPLACE</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>params</parameter></term>
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<listitem>
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<para>
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Returns the requested data.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="description"><title>Description</title>
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<para>
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<function>glGetTexEnv</function> returns in <parameter>params</parameter> selected values of a texture environment that
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was specified with <citerefentry><refentrytitle>glTexEnv</refentrytitle></citerefentry>.
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<parameter>target</parameter> specifies a texture environment.
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</para>
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<para>
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When <parameter>target</parameter> is <constant>GL_TEXTURE_FILTER_CONTROL</constant>,
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<parameter>pname</parameter> must be <constant>GL_TEXTURE_LOD_BIAS</constant>.
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When <parameter>target</parameter> is <constant>GL_POINT_SPRITE</constant>,
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<parameter>pname</parameter> must be <constant>GL_COORD_REPLACE</constant>.
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When <parameter>target</parameter> is
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<constant>GL_TEXTURE_ENV</constant>, <parameter>pname</parameter> can be <constant>GL_TEXTURE_ENV_MODE</constant>,
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<constant>GL_TEXTURE_ENV_COLOR</constant>, <constant>GL_COMBINE_RGB</constant>, <constant>GL_COMBINE_ALPHA</constant>,
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<constant>GL_RGB_SCALE</constant>, <constant>GL_ALPHA_SCALE</constant>,
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<constant>GL_SRC0_RGB</constant>, <constant>GL_SRC1_RGB</constant>, <constant>GL_SRC2_RGB</constant>,
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<constant>GL_SRC0_ALPHA</constant>, <constant>GL_SRC1_ALPHA</constant>, or <constant>GL_SRC2_ALPHA</constant>.
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</para>
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<para>
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<parameter>pname</parameter> names a specific texture environment parameter, as follows:
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</para>
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<variablelist>
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<varlistentry>
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<term><constant>GL_TEXTURE_ENV_MODE</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns the single-valued texture environment mode,
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a symbolic constant. The initial value is <constant>GL_MODULATE</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_TEXTURE_ENV_COLOR</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns four integer or floating-point values that are the
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texture environment color.
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Integer values,
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when requested,
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are linearly mapped from the internal floating-point representation
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such that 1.0 maps to the most positive representable integer,
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and
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<inlineequation><mml:math>
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<!-- eqn: -1.0:-->
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<mml:mn>-1.0</mml:mn>
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</mml:math></inlineequation>
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maps to the most negative representable integer. The initial
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value is (0, 0, 0, 0).
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_TEXTURE_LOD_BIAS</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single floating-point value that is the texture
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level-of-detail bias. The initial value is 0.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_COMBINE_RGB</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the current
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RGB combine mode. The initial value is <constant>GL_MODULATE</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_COMBINE_ALPHA</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the current
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alpha combine mode. The initial value is <constant>GL_MODULATE</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_SRC0_RGB</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner zero's RGB source. The initial value is <constant>GL_TEXTURE</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_SRC1_RGB</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner one's RGB source. The initial value is <constant>GL_PREVIOUS</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_SRC2_RGB</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner two's RGB source. The initial value is <constant>GL_CONSTANT</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_SRC0_ALPHA</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner zero's alpha source. The initial value is <constant>GL_TEXTURE</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_SRC1_ALPHA</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner one's alpha source. The initial value is <constant>GL_PREVIOUS</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_SRC2_ALPHA</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner two's alpha source. The initial value is <constant>GL_CONSTANT</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_OPERAND0_RGB</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner zero's RGB operand. The initial value is <constant>GL_SRC_COLOR</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_OPERAND1_RGB</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner one's RGB operand. The initial value is <constant>GL_SRC_COLOR</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_OPERAND2_RGB</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner two's RGB operand. The initial value is <constant>GL_SRC_ALPHA</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_OPERAND0_ALPHA</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner zero's alpha operand. The initial value is <constant>GL_SRC_ALPHA</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_OPERAND1_ALPHA</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner one's alpha operand. The initial value is <constant>GL_SRC_ALPHA</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_OPERAND2_ALPHA</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single symbolic constant value representing the texture
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combiner two's alpha operand. The initial value is <constant>GL_SRC_ALPHA</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_RGB_SCALE</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single floating-point value representing the current RGB
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texture combiner scaling factor. The initial value is 1.0.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_ALPHA_SCALE</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single floating-point value representing the current alpha
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texture combiner scaling factor. The initial value is 1.0.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_COORD_REPLACE</constant></term>
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<listitem>
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<para>
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<parameter>params</parameter> returns a single boolean value representing the current point sprite
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texture coordinate replacement enable state. The initial value is <constant>GL_FALSE</constant>.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="notes"><title>Notes</title>
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<para>
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If an error is generated,
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no change is made to the contents of <parameter>params</parameter>.
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</para>
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<para>
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For OpenGL versions 1.3 and greater, or when the <code>ARB_multitexture</code> extension is supported, <function>glGetTexEnv</function> returns
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the texture environment parameters for the active texture unit.
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</para>
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<para>
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<constant>GL_COMBINE_RGB</constant>,
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<constant>GL_COMBINE_ALPHA</constant>,
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<constant>GL_SRC0_RGB</constant>,
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<constant>GL_SRC1_RGB</constant>,
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<constant>GL_SRC2_RGB</constant>,
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<constant>GL_SRC0_ALPHA</constant>,
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<constant>GL_SRC1_ALPHA</constant>,
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<constant>GL_SRC2_ALPHA</constant>,
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<constant>GL_OPERAND0_RGB</constant>,
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<constant>GL_OPERAND1_RGB</constant>,
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<constant>GL_OPERAND2_RGB</constant>,
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<constant>GL_OPERAND0_ALPHA</constant>,
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<constant>GL_OPERAND1_ALPHA</constant>,
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<constant>GL_OPERAND2_ALPHA</constant>,
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<constant>GL_RGB_SCALE</constant>, and
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<constant>GL_ALPHA_SCALE</constant> are available only if the GL version is 1.3 or greater.
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</para>
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<para>
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<constant>GL_TEXTURE_FILTER_CONTROL</constant> and <constant>GL_TEXTURE_LOD_BIAS</constant> are available
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only if the GL version is 1.4 or greater.
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</para>
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<para>
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<constant>GL_POINT_SPRITE</constant> and <constant>GL_COORD_REPLACE</constant> are available
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only if the GL version is 2.0 or greater.
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</para>
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</refsect1>
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<refsect1 id="errors"><title>Errors</title>
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<para>
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<constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> or <parameter>pname</parameter> is not an
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accepted value.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <function>glGetTexEnv</function>
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is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
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and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
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</para>
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</refsect1>
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<refsect1 id="seealso"><title>See Also</title>
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<para>
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<citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glTexEnv</refentrytitle></citerefentry>
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</para>
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</refsect1>
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<refsect1 id="Copyright"><title>Copyright</title>
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<para>
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Copyright <trademark class="copyright"></trademark> 1991-2006
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Silicon Graphics, Inc. This document is licensed under the SGI
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Free Software B License. For details, see
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<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
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</para>
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</refsect1>
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</refentry>
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