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<refentry id="glGetTexEnv">
<refmeta>
<refmetainfo>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
</refmetainfo>
<refentrytitle>glGetTexEnv</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glGetTexEnv</refname>
<refpurpose>return texture environment parameters</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glGetTexEnvfv</function></funcdef>
<paramdef>GLenum <parameter>target</parameter></paramdef>
<paramdef>GLenum <parameter>pname</parameter></paramdef>
<paramdef>GLfloat * <parameter>params</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<para></para>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glGetTexEnviv</function></funcdef>
<paramdef>GLenum <parameter>target</parameter></paramdef>
<paramdef>GLenum <parameter>pname</parameter></paramdef>
<paramdef>GLint * <parameter>params</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>target</parameter></term>
<listitem>
<para>
Specifies a texture environment. May be
<constant>GL_TEXTURE_ENV</constant>,
<constant>GL_TEXTURE_FILTER_CONTROL</constant>, or
<constant>GL_POINT_SPRITE</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>pname</parameter></term>
<listitem>
<para>
Specifies the symbolic name of a texture environment parameter.
Accepted values are <constant>GL_TEXTURE_ENV_MODE</constant>, <constant>GL_TEXTURE_ENV_COLOR</constant>,
<constant>GL_TEXTURE_LOD_BIAS</constant>,
<constant>GL_COMBINE_RGB</constant>,
<constant>GL_COMBINE_ALPHA</constant>,
<constant>GL_SRC0_RGB</constant>,
<constant>GL_SRC1_RGB</constant>,
<constant>GL_SRC2_RGB</constant>,
<constant>GL_SRC0_ALPHA</constant>,
<constant>GL_SRC1_ALPHA</constant>,
<constant>GL_SRC2_ALPHA</constant>,
<constant>GL_OPERAND0_RGB</constant>,
<constant>GL_OPERAND1_RGB</constant>,
<constant>GL_OPERAND2_RGB</constant>,
<constant>GL_OPERAND0_ALPHA</constant>,
<constant>GL_OPERAND1_ALPHA</constant>,
<constant>GL_OPERAND2_ALPHA</constant>,
<constant>GL_RGB_SCALE</constant>,
<constant>GL_ALPHA_SCALE</constant>, or
<constant>GL_COORD_REPLACE</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>glGetTexEnv</function> returns in <parameter>params</parameter> selected values of a texture environment that
was specified with <citerefentry><refentrytitle>glTexEnv</refentrytitle></citerefentry>.
<parameter>target</parameter> specifies a texture environment.
</para>
<para>
When <parameter>target</parameter> is <constant>GL_TEXTURE_FILTER_CONTROL</constant>,
<parameter>pname</parameter> must be <constant>GL_TEXTURE_LOD_BIAS</constant>.
When <parameter>target</parameter> is <constant>GL_POINT_SPRITE</constant>,
<parameter>pname</parameter> must be <constant>GL_COORD_REPLACE</constant>.
When <parameter>target</parameter> is
<constant>GL_TEXTURE_ENV</constant>, <parameter>pname</parameter> can be <constant>GL_TEXTURE_ENV_MODE</constant>,
<constant>GL_TEXTURE_ENV_COLOR</constant>, <constant>GL_COMBINE_RGB</constant>, <constant>GL_COMBINE_ALPHA</constant>,
<constant>GL_RGB_SCALE</constant>, <constant>GL_ALPHA_SCALE</constant>,
<constant>GL_SRC0_RGB</constant>, <constant>GL_SRC1_RGB</constant>, <constant>GL_SRC2_RGB</constant>,
<constant>GL_SRC0_ALPHA</constant>, <constant>GL_SRC1_ALPHA</constant>, or <constant>GL_SRC2_ALPHA</constant>.
</para>
<para>
<parameter>pname</parameter> names a specific texture environment parameter, as follows:
</para>
<variablelist>
<varlistentry>
<term><constant>GL_TEXTURE_ENV_MODE</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns the single-valued texture environment mode,
a symbolic constant. The initial value is <constant>GL_MODULATE</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_TEXTURE_ENV_COLOR</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns four integer or floating-point values that are the
texture environment color.
Integer values,
when requested,
are linearly mapped from the internal floating-point representation
such that 1.0 maps to the most positive representable integer,
and
<inlineequation><mml:math>
<!-- eqn: -1.0:-->
<mml:mn>-1.0</mml:mn>
</mml:math></inlineequation>
maps to the most negative representable integer. The initial
value is (0, 0, 0, 0).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_TEXTURE_LOD_BIAS</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single floating-point value that is the texture
level-of-detail bias. The initial value is 0.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_COMBINE_RGB</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the current
RGB combine mode. The initial value is <constant>GL_MODULATE</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_COMBINE_ALPHA</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the current
alpha combine mode. The initial value is <constant>GL_MODULATE</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_SRC0_RGB</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner zero's RGB source. The initial value is <constant>GL_TEXTURE</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_SRC1_RGB</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner one's RGB source. The initial value is <constant>GL_PREVIOUS</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_SRC2_RGB</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner two's RGB source. The initial value is <constant>GL_CONSTANT</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_SRC0_ALPHA</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner zero's alpha source. The initial value is <constant>GL_TEXTURE</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_SRC1_ALPHA</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner one's alpha source. The initial value is <constant>GL_PREVIOUS</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_SRC2_ALPHA</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner two's alpha source. The initial value is <constant>GL_CONSTANT</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_OPERAND0_RGB</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner zero's RGB operand. The initial value is <constant>GL_SRC_COLOR</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_OPERAND1_RGB</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner one's RGB operand. The initial value is <constant>GL_SRC_COLOR</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_OPERAND2_RGB</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner two's RGB operand. The initial value is <constant>GL_SRC_ALPHA</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_OPERAND0_ALPHA</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner zero's alpha operand. The initial value is <constant>GL_SRC_ALPHA</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_OPERAND1_ALPHA</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner one's alpha operand. The initial value is <constant>GL_SRC_ALPHA</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_OPERAND2_ALPHA</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single symbolic constant value representing the texture
combiner two's alpha operand. The initial value is <constant>GL_SRC_ALPHA</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_RGB_SCALE</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single floating-point value representing the current RGB
texture combiner scaling factor. The initial value is 1.0.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_ALPHA_SCALE</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single floating-point value representing the current alpha
texture combiner scaling factor. The initial value is 1.0.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_COORD_REPLACE</constant></term>
<listitem>
<para>
<parameter>params</parameter> returns a single boolean value representing the current point sprite
texture coordinate replacement enable state. The initial value is <constant>GL_FALSE</constant>.
</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>glGetTexEnv</function> returns
the texture environment parameters for the active texture unit.
</para>
<para>
<constant>GL_COMBINE_RGB</constant>,
<constant>GL_COMBINE_ALPHA</constant>,
<constant>GL_SRC0_RGB</constant>,
<constant>GL_SRC1_RGB</constant>,
<constant>GL_SRC2_RGB</constant>,
<constant>GL_SRC0_ALPHA</constant>,
<constant>GL_SRC1_ALPHA</constant>,
<constant>GL_SRC2_ALPHA</constant>,
<constant>GL_OPERAND0_RGB</constant>,
<constant>GL_OPERAND1_RGB</constant>,
<constant>GL_OPERAND2_RGB</constant>,
<constant>GL_OPERAND0_ALPHA</constant>,
<constant>GL_OPERAND1_ALPHA</constant>,
<constant>GL_OPERAND2_ALPHA</constant>,
<constant>GL_RGB_SCALE</constant>, and
<constant>GL_ALPHA_SCALE</constant> are available only if the GL version is 1.3 or greater.
</para>
<para>
<constant>GL_TEXTURE_FILTER_CONTROL</constant> and <constant>GL_TEXTURE_LOD_BIAS</constant> are available
only if the GL version is 1.4 or greater.
</para>
<para>
<constant>GL_POINT_SPRITE</constant> and <constant>GL_COORD_REPLACE</constant> are available
only if the GL version is 2.0 or greater.
</para>
</refsect1>
<refsect1 id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> or <parameter>pname</parameter> is not an
accepted value.
</para>
<para>
<constant>GL_INVALID_OPERATION</constant> is generated if <function>glGetTexEnv</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>glTexEnv</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>