mirror of
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1361 lines
85 KiB
XML
1361 lines
85 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="glTexParameter">
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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>glTexParameter</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glTexParameter</refname>
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<refpurpose>set texture 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>glTexParameterf</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>param</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glTexParameteri</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>param</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<!-- eqn: ignoring delim $$ -->
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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 the target texture,
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which must be either <constant>GL_TEXTURE_1D</constant>, <constant>GL_TEXTURE_2D</constant>,
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<constant>GL_TEXTURE_3D</constant>, <constant>GL_TEXTURE_1D_ARRAY</constant>,
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<constant>GL_TEXTURE_2D_ARRAY</constant>, <constant>GL_TEXTURE_RECTANGLE</constant>,
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or <constant>GL_TEXTURE_CUBE_MAP</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 single-valued texture parameter.
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<parameter>pname</parameter> can be one of the following:
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<constant>GL_TEXTURE_BASE_LEVEL</constant>,
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<constant>GL_TEXTURE_COMPARE_FUNC</constant>,
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<constant>GL_TEXTURE_COMPARE_MODE</constant>,
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<constant>GL_TEXTURE_LOD_BIAS</constant>,
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<constant>GL_TEXTURE_MIN_FILTER</constant>,
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<constant>GL_TEXTURE_MAG_FILTER</constant>,
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<constant>GL_TEXTURE_MIN_LOD</constant>,
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<constant>GL_TEXTURE_MAX_LOD</constant>,
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<constant>GL_TEXTURE_MAX_LEVEL</constant>,
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<constant>GL_TEXTURE_SWIZZLE_R</constant>,
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<constant>GL_TEXTURE_SWIZZLE_G</constant>,
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<constant>GL_TEXTURE_SWIZZLE_B</constant>,
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<constant>GL_TEXTURE_SWIZZLE_A</constant>,
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<constant>GL_TEXTURE_WRAP_S</constant>,
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<constant>GL_TEXTURE_WRAP_T</constant>, or
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<constant>GL_TEXTURE_WRAP_R</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>param</parameter></term>
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<listitem>
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<para>
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Specifies the value of <parameter>pname</parameter>.
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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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<refsynopsisdiv><title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glTexParameterfv</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>const GLfloat * <parameter>params</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glTexParameteriv</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>const GLint * <parameter>params</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glTexParameterIiv</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>const GLint * <parameter>params</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glTexParameterIuiv</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>const GLuint * <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="parameters2"><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 the target texture,
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which must be either <constant>GL_TEXTURE_1D</constant>, <constant>GL_TEXTURE_2D</constant>,
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<constant>GL_TEXTURE_3D</constant>, <constant>GL_TEXTURE_1D_ARRAY</constant>,
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<constant>GL_TEXTURE_2D_ARRAY</constant>, <constant>GL_TEXTURE_RECTANGLE</constant>,
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or <constant>GL_TEXTURE_CUBE_MAP</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 parameter.
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<parameter>pname</parameter> can be one of the following:
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<constant>GL_TEXTURE_BASE_LEVEL</constant>,
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<constant>GL_TEXTURE_BORDER_COLOR</constant>,
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<constant>GL_TEXTURE_COMPARE_FUNC</constant>,
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<constant>GL_TEXTURE_COMPARE_MODE</constant>,
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<constant>GL_TEXTURE_LOD_BIAS</constant>,
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<constant>GL_TEXTURE_MIN_FILTER</constant>,
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<constant>GL_TEXTURE_MAG_FILTER</constant>,
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<constant>GL_TEXTURE_MIN_LOD</constant>,
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<constant>GL_TEXTURE_MAX_LOD</constant>,
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<constant>GL_TEXTURE_MAX_LEVEL</constant>,
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<constant>GL_TEXTURE_SWIZZLE_R</constant>,
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<constant>GL_TEXTURE_SWIZZLE_G</constant>,
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<constant>GL_TEXTURE_SWIZZLE_B</constant>,
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<constant>GL_TEXTURE_SWIZZLE_A</constant>,
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<constant>GL_TEXTURE_SWIZZLE_RGBA</constant>,
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<constant>GL_TEXTURE_WRAP_S</constant>,
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<constant>GL_TEXTURE_WRAP_T</constant>, or
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<constant>GL_TEXTURE_WRAP_R</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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Specifies a pointer to an array where the value or values of <parameter>pname</parameter>
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are stored.
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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>glTexParameter</function> assigns the value or values in <parameter>params</parameter> to the texture parameter
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specified as <parameter>pname</parameter>.
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<parameter>target</parameter> defines the target texture,
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either <constant>GL_TEXTURE_1D</constant>, <constant>GL_TEXTURE_2D</constant>, <constant>GL_TEXTURE_1D_ARRAY</constant>,
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<constant>GL_TEXTURE_2D_ARRAY</constant>, <constant>GL_TEXTURE_RECTANGLE</constant>, or <constant>GL_TEXTURE_3D</constant>.
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The following symbols are accepted in <parameter>pname</parameter>:
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</para>
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<variablelist>
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<varlistentry>
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<term><constant>GL_TEXTURE_BASE_LEVEL</constant></term>
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<listitem>
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<para>
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Specifies the index of the lowest defined mipmap level. This is an
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integer value. The initial value is 0.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>
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</para>
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<variablelist>
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<varlistentry>
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<term><constant>GL_TEXTURE_BORDER_COLOR</constant></term>
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<listitem>
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<para>
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The data in <parameter>params</parameter> specifies four values that define the border values that
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should be used for border texels. If a texel is sampled from the border of the texture, the
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values of <constant>GL_TEXTURE_BORDER_COLOR</constant> are interpreted as an RGBA color to match the
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texture's internal format and substituted for the non-existent texel data. If the texture contains depth
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components, the first component of <constant>GL_TEXTURE_BORDER_COLOR</constant> is interpreted as a depth value.
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The initial value is
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<inlineequation><mml:math>
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<mml:mrow>
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<mml:mfenced open="(" close=")">
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<mml:mrow>
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0.0, 0.0, 0.0, 0.0
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</mml:mrow>
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</mml:mfenced>
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</mml:mrow>
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</mml:math></inlineequation>.
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</para>
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<para>
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If the values for <constant>GL_TEXTURE_BORDER_COLOR</constant> are specified with <function>glTexParameterIiv</function>
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or <function>glTexParameterIuiv</function>, the values are stored unmodified with an internal data type of
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integer. If specified with <function>glTexParameteriv</function>, they are converted to floating point with the following
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equation:
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<inlineequation><mml:math>
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<mml:mrow>
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<mml:mi mathvariant="italic">f</mml:mi>
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<mml:mo>=</mml:mo>
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<mml:mfrac>
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<mml:mrow>
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<mml:msub><mml:mn>2</mml:mn>
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<mml:mi mathvariant="italic">c</mml:mi>
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</mml:msub>
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<mml:mo>+</mml:mo>
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<mml:mn>1</mml:mn>
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</mml:mrow>
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<mml:mrow>
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<mml:msup><mml:mn>2</mml:mn>
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<mml:mi mathvariant="italic">b</mml:mi>
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</mml:msup>
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<mml:mo>-</mml:mo>
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<mml:mn>1</mml:mn>
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</mml:mrow>
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</mml:mfrac>
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</mml:mrow>
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</mml:math></inlineequation>.
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If specified with <function>glTexParameterfv</function>, they are stored unmodified as floating-point values.
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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_COMPARE_FUNC</constant></term>
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<listitem>
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<para>
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Specifies the comparison operator used when <constant>GL_TEXTURE_COMPARE_MODE</constant> is
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set to <constant>GL_COMPARE_REF_TO_TEXTURE</constant>. Permissible values are:
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<informaltable frame="topbot">
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<tgroup cols="2" align="left">
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<colspec/>
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<colspec/>
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<thead>
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<row>
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<entry rowsep="1" align="left"><emphasis role="bold">
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Texture Comparison Function
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</emphasis></entry>
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<entry rowsep="1" align="left"><emphasis role="bold">
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Computed result
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</emphasis></entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry align="left">
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<constant>GL_LEQUAL</constant>
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</entry>
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<entry align="left">
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<informalequation><mml:math>
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<!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
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<mml:mrow>
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<mml:mi mathvariant="italic">result</mml:mi>
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<mml:mo>=</mml:mo>
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<mml:mfenced open="{" close="">
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<mml:mrow>
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<mml:mtable>
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<mml:mtr><mml:mtd>
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<mml:mn>1.0</mml:mn>
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</mml:mtd></mml:mtr>
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<mml:mtr><mml:mtd>
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<mml:mn>0.0</mml:mn>
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</mml:mtd></mml:mtr>
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</mml:mtable>
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<mml:mo>⁢ </mml:mo>
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<mml:mtable>
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<mml:mtr><mml:mtd>
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<mml:mrow>
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<mml:mi mathvariant="italic">r</mml:mi>
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<mml:mo><=</mml:mo>
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<mml:mfenced open="" close="">
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<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
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<mml:mi mathvariant="italic">t</mml:mi>
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</mml:msub>
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</mml:mfenced>
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</mml:mrow>
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</mml:mtd></mml:mtr>
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<mml:mtr><mml:mtd>
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<mml:mrow>
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<mml:mi mathvariant="italic">r</mml:mi>
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<mml:mo>></mml:mo>
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<mml:mfenced open="" close="">
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<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
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<mml:mi mathvariant="italic">t</mml:mi>
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</mml:msub>
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</mml:mfenced>
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</mml:mrow>
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</mml:mtd></mml:mtr>
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</mml:mtable>
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</mml:mrow>
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</mml:mfenced>
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</mml:mrow>
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</mml:math></informalequation>
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</entry>
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</row>
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<row>
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<entry align="left">
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<constant>GL_GEQUAL</constant>
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</entry>
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<entry align="left">
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<informalequation><mml:math>
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<!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
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<mml:mrow>
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<mml:mi mathvariant="italic">result</mml:mi>
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<mml:mo>=</mml:mo>
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<mml:mfenced open="{" close="">
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<mml:mrow>
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<mml:mtable>
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<mml:mtr><mml:mtd>
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<mml:mn>1.0</mml:mn>
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</mml:mtd></mml:mtr>
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<mml:mtr><mml:mtd>
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<mml:mn>0.0</mml:mn>
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</mml:mtd></mml:mtr>
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</mml:mtable>
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<mml:mo>⁢ </mml:mo>
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<mml:mtable>
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<mml:mtr><mml:mtd>
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<mml:mrow>
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<mml:mi mathvariant="italic">r</mml:mi>
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<mml:mo>>=</mml:mo>
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<mml:mfenced open="" close="">
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<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
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<mml:mi mathvariant="italic">t</mml:mi>
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</mml:msub>
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</mml:mfenced>
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</mml:mrow>
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</mml:mtd></mml:mtr>
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<mml:mtr><mml:mtd>
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<mml:mrow>
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<mml:mi mathvariant="italic">r</mml:mi>
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<mml:mo><</mml:mo>
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<mml:mfenced open="" close="">
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<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
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<mml:mi mathvariant="italic">t</mml:mi>
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</mml:msub>
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</mml:mfenced>
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</mml:mrow>
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</mml:mtd></mml:mtr>
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</mml:mtable>
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</mml:mrow>
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</mml:mfenced>
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</mml:mrow>
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</mml:math></informalequation>
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</entry>
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</row>
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<row>
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<entry align="left">
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<constant>GL_LESS</constant>
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</entry>
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<entry align="left">
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<informalequation><mml:math>
|
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<!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
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<mml:mrow>
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<mml:mi mathvariant="italic">result</mml:mi>
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<mml:mo>=</mml:mo>
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<mml:mfenced open="{" close="">
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<mml:mrow>
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<mml:mtable>
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<mml:mtr><mml:mtd>
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<mml:mn>1.0</mml:mn>
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</mml:mtd></mml:mtr>
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<mml:mtr><mml:mtd>
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<mml:mn>0.0</mml:mn>
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</mml:mtd></mml:mtr>
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</mml:mtable>
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<mml:mo>⁢ </mml:mo>
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<mml:mtable>
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<mml:mtr><mml:mtd>
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<mml:mrow>
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<mml:mi mathvariant="italic">r</mml:mi>
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<mml:mo><</mml:mo>
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<mml:mfenced open="" close="">
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<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
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<mml:mi mathvariant="italic">t</mml:mi>
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</mml:msub>
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</mml:mfenced>
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</mml:mrow>
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</mml:mtd></mml:mtr>
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<mml:mtr><mml:mtd>
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<mml:mrow>
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<mml:mi mathvariant="italic">r</mml:mi>
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<mml:mo>>=</mml:mo>
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<mml:mfenced open="" close="">
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<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
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<mml:mi mathvariant="italic">t</mml:mi>
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</mml:msub>
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</mml:mfenced>
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</mml:mrow>
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</mml:mtd></mml:mtr>
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</mml:mtable>
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</mml:mrow>
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</mml:mfenced>
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</mml:mrow>
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</mml:math></informalequation>
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</entry>
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</row>
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<row>
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<entry align="left">
|
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<constant>GL_GREATER</constant>
|
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</entry>
|
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<entry align="left">
|
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<informalequation><mml:math>
|
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<!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
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<mml:mrow>
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<mml:mi mathvariant="italic">result</mml:mi>
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<mml:mo>=</mml:mo>
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<mml:mfenced open="{" close="">
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<mml:mrow>
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<mml:mtable>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mn>1.0</mml:mn>
|
|
</mml:mtd></mml:mtr>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mn>0.0</mml:mn>
|
|
</mml:mtd></mml:mtr>
|
|
</mml:mtable>
|
|
<mml:mo>⁢ </mml:mo>
|
|
<mml:mtable>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">r</mml:mi>
|
|
<mml:mo>></mml:mo>
|
|
<mml:mfenced open="" close="">
|
|
<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
|
|
<mml:mi mathvariant="italic">t</mml:mi>
|
|
</mml:msub>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:mtd></mml:mtr>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">r</mml:mi>
|
|
<mml:mo><=</mml:mo>
|
|
<mml:mfenced open="" close="">
|
|
<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
|
|
<mml:mi mathvariant="italic">t</mml:mi>
|
|
</mml:msub>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:mtd></mml:mtr>
|
|
</mml:mtable>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:math></informalequation>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry align="left">
|
|
<constant>GL_EQUAL</constant>
|
|
</entry>
|
|
<entry align="left">
|
|
<informalequation><mml:math>
|
|
<!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">result</mml:mi>
|
|
<mml:mo>=</mml:mo>
|
|
<mml:mfenced open="{" close="">
|
|
<mml:mrow>
|
|
<mml:mtable>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mn>1.0</mml:mn>
|
|
</mml:mtd></mml:mtr>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mn>0.0</mml:mn>
|
|
</mml:mtd></mml:mtr>
|
|
</mml:mtable>
|
|
<mml:mo>⁢ </mml:mo>
|
|
<mml:mtable>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">r</mml:mi>
|
|
<mml:mo>=</mml:mo>
|
|
<mml:mfenced open="" close="">
|
|
<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
|
|
<mml:mi mathvariant="italic">t</mml:mi>
|
|
</mml:msub>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:mtd></mml:mtr>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">r</mml:mi>
|
|
<mml:mo>≠</mml:mo>
|
|
<mml:mfenced open="" close="">
|
|
<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
|
|
<mml:mi mathvariant="italic">t</mml:mi>
|
|
</mml:msub>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:mtd></mml:mtr>
|
|
</mml:mtable>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:math></informalequation>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry align="left">
|
|
<constant>GL_NOTEQUAL</constant>
|
|
</entry>
|
|
<entry align="left">
|
|
<informalequation><mml:math>
|
|
<!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">result</mml:mi>
|
|
<mml:mo>=</mml:mo>
|
|
<mml:mfenced open="{" close="">
|
|
<mml:mrow>
|
|
<mml:mtable>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mn>1.0</mml:mn>
|
|
</mml:mtd></mml:mtr>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mn>0.0</mml:mn>
|
|
</mml:mtd></mml:mtr>
|
|
</mml:mtable>
|
|
<mml:mo>⁢ </mml:mo>
|
|
<mml:mtable>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">r</mml:mi>
|
|
<mml:mo>≠</mml:mo>
|
|
<mml:mfenced open="" close="">
|
|
<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
|
|
<mml:mi mathvariant="italic">t</mml:mi>
|
|
</mml:msub>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:mtd></mml:mtr>
|
|
<mml:mtr><mml:mtd>
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">r</mml:mi>
|
|
<mml:mo>=</mml:mo>
|
|
<mml:mfenced open="" close="">
|
|
<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
|
|
<mml:mi mathvariant="italic">t</mml:mi>
|
|
</mml:msub>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:mtd></mml:mtr>
|
|
</mml:mtable>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:math></informalequation>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry align="left">
|
|
<constant>GL_ALWAYS</constant>
|
|
</entry>
|
|
<entry align="left">
|
|
<informalequation>
|
|
<mml:math>
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">result</mml:mi>
|
|
<mml:mo>=</mml:mo>
|
|
<mml:mi>1.0</mml:mi>
|
|
</mml:mrow>
|
|
</mml:math>
|
|
</informalequation>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry align="left">
|
|
<constant>GL_NEVER</constant>
|
|
</entry>
|
|
<entry align="left">
|
|
<informalequation>
|
|
<mml:math>
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">result</mml:mi>
|
|
<mml:mo>=</mml:mo>
|
|
<mml:mi>0.0</mml:mi>
|
|
</mml:mrow>
|
|
</mml:math>
|
|
</informalequation>
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</informaltable>
|
|
where <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
|
|
is the current interpolated texture coordinate, and
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: D sub t: -->
|
|
<mml:msub><mml:mi mathvariant="italic">D</mml:mi>
|
|
<mml:mi mathvariant="italic">t</mml:mi>
|
|
</mml:msub>
|
|
</mml:math></inlineequation>
|
|
is the depth texture value sampled from the currently bound depth texture.
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">result</mml:mi></mml:math></inlineequation>
|
|
is assigned to the the red channel.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_COMPARE_MODE</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies the texture comparison mode for currently bound depth textures.
|
|
That is, a texture whose internal format is <constant>GL_DEPTH_COMPONENT_*</constant>; see
|
|
<citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>)
|
|
Permissible values are:
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_COMPARE_REF_TO_TEXTURE</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies that the interpolated and clamped
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
|
|
texture coordinate should
|
|
be compared to the value in the currently bound depth texture. See the
|
|
discussion of <constant>GL_TEXTURE_COMPARE_FUNC</constant> for details of how the comparison
|
|
is evaluated. The result of the comparison is assigned to the red channel.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GL_NONE</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies that the red channel should be assigned the
|
|
appropriate value from the currently bound depth texture.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_LOD_BIAS</constant></term>
|
|
<listitem>
|
|
<para>
|
|
<parameter>params</parameter> specifies a fixed bias value that is to be added to the level-of-detail
|
|
parameter for the texture before texture sampling. The specified value is added to the shader-supplied
|
|
bias value (if any) and subsequently clamped into the implementation-defined range
|
|
<inlineequation><mml:math>
|
|
<mml:mfenced open="[" close="]">
|
|
<mml:mfenced open="" close="">
|
|
<mml:mrow>
|
|
-
|
|
<mml:msub><mml:mi mathvariant="italic">bias</mml:mi>
|
|
<mml:mi mathvariant="italic">max</mml:mi>
|
|
</mml:msub>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
<mml:mrow>
|
|
<mml:mfenced open="" close="">
|
|
<mml:mrow>
|
|
<mml:msub><mml:mi mathvariant="italic">bias</mml:mi>
|
|
<mml:mi mathvariant="italic">max</mml:mi>
|
|
</mml:msub>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
</mml:math></inlineequation>,
|
|
where
|
|
<inlineequation><mml:math>
|
|
<mml:mrow>
|
|
<mml:msub><mml:mi mathvariant="italic">bias</mml:mi>
|
|
<mml:mi mathvariant="italic">max</mml:mi>
|
|
</mml:msub>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>
|
|
is the value of the implementation defined constant <constant>GL_MAX_TEXTURE_LOD_BIAS</constant>. The initial value is 0.0.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_MIN_FILTER</constant></term>
|
|
<listitem>
|
|
<para>
|
|
The texture minifying function is used whenever the level-of-detail function
|
|
used when sampling from the texture determines that the texture should be minified.
|
|
There are six defined minifying functions.
|
|
Two of them use either the nearest texture elements or a weighted average of multiple texture elements
|
|
to compute the texture value.
|
|
The other four use mipmaps.
|
|
</para>
|
|
<para>
|
|
A mipmap is an ordered set of arrays representing the same image
|
|
at progressively lower resolutions.
|
|
If the texture has dimensions
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: 2 sup n times 2 sup m: -->
|
|
<mml:mrow>
|
|
<mml:msup><mml:mn>2</mml:mn>
|
|
<mml:mi mathvariant="italic">n</mml:mi>
|
|
</mml:msup>
|
|
<mml:mo>×</mml:mo>
|
|
<mml:msup><mml:mn>2</mml:mn>
|
|
<mml:mi mathvariant="italic">m</mml:mi>
|
|
</mml:msup>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>,
|
|
there are
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: max ( n, m ) + 1: -->
|
|
<mml:mrow>
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">max</mml:mi>
|
|
<mml:mo>⁡</mml:mo>
|
|
<mml:mfenced open="(" close=")">
|
|
<mml:mi mathvariant="italic">n</mml:mi>
|
|
<mml:mi mathvariant="italic">m</mml:mi>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
<mml:mo>+</mml:mo>
|
|
<mml:mn>1</mml:mn>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>
|
|
mipmaps.
|
|
The first mipmap is the original texture,
|
|
with dimensions
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: 2 sup n times 2 sup m: -->
|
|
<mml:mrow>
|
|
<mml:msup><mml:mn>2</mml:mn>
|
|
<mml:mi mathvariant="italic">n</mml:mi>
|
|
</mml:msup>
|
|
<mml:mo>×</mml:mo>
|
|
<mml:msup><mml:mn>2</mml:mn>
|
|
<mml:mi mathvariant="italic">m</mml:mi>
|
|
</mml:msup>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>.
|
|
Each subsequent mipmap has dimensions
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: 2 sup { k - 1 } times 2 sup { l - 1 }: -->
|
|
<mml:mrow>
|
|
<mml:msup><mml:mn>2</mml:mn>
|
|
<mml:mfenced open="" close="">
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">k</mml:mi>
|
|
<mml:mo>-</mml:mo>
|
|
<mml:mn>1</mml:mn>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
</mml:msup>
|
|
<mml:mo>×</mml:mo>
|
|
<mml:msup><mml:mn>2</mml:mn>
|
|
<mml:mfenced open="" close="">
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">l</mml:mi>
|
|
<mml:mo>-</mml:mo>
|
|
<mml:mn>1</mml:mn>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
</mml:msup>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>,
|
|
where
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: 2 sup k times 2 sup l: -->
|
|
<mml:mrow>
|
|
<mml:msup><mml:mn>2</mml:mn>
|
|
<mml:mi mathvariant="italic">k</mml:mi>
|
|
</mml:msup>
|
|
<mml:mo>×</mml:mo>
|
|
<mml:msup><mml:mn>2</mml:mn>
|
|
<mml:mi mathvariant="italic">l</mml:mi>
|
|
</mml:msup>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>
|
|
are the dimensions of the previous mipmap,
|
|
until either
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: k = 0: -->
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">k</mml:mi>
|
|
<mml:mo>=</mml:mo>
|
|
<mml:mn>0</mml:mn>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>
|
|
or
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: l = 0: -->
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">l</mml:mi>
|
|
<mml:mo>=</mml:mo>
|
|
<mml:mn>0</mml:mn>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>.
|
|
At that point,
|
|
subsequent mipmaps have dimension
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: 1 times 2 sup { l - 1 }: -->
|
|
<mml:mrow>
|
|
<mml:mn>1</mml:mn>
|
|
<mml:mo>×</mml:mo>
|
|
<mml:msup><mml:mn>2</mml:mn>
|
|
<mml:mfenced open="" close="">
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">l</mml:mi>
|
|
<mml:mo>-</mml:mo>
|
|
<mml:mn>1</mml:mn>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
</mml:msup>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>
|
|
or
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: 2 sup { k - 1} times 1: -->
|
|
<mml:mrow>
|
|
<mml:msup><mml:mn>2</mml:mn>
|
|
<mml:mfenced open="" close="">
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">k</mml:mi>
|
|
<mml:mo>-</mml:mo>
|
|
<mml:mn>1</mml:mn>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
</mml:msup>
|
|
<mml:mo>×</mml:mo>
|
|
<mml:mn>1</mml:mn>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>
|
|
until the final mipmap,
|
|
which has dimension
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: 1 times 1: -->
|
|
<mml:mrow>
|
|
<mml:mn>1</mml:mn>
|
|
<mml:mo>×</mml:mo>
|
|
<mml:mn>1</mml:mn>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>.
|
|
To define the mipmaps, call <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>, or <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>
|
|
with the <emphasis>level</emphasis> argument indicating the order of the mipmaps.
|
|
Level 0 is the original texture;
|
|
level
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: max ( n, m ): -->
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">max</mml:mi>
|
|
<mml:mo>⁡</mml:mo>
|
|
<mml:mfenced open="(" close=")">
|
|
<mml:mi mathvariant="italic">n</mml:mi>
|
|
<mml:mi mathvariant="italic">m</mml:mi>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>
|
|
is the final
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: 1 times 1: -->
|
|
<mml:mrow>
|
|
<mml:mn>1</mml:mn>
|
|
<mml:mo>×</mml:mo>
|
|
<mml:mn>1</mml:mn>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>
|
|
mipmap.
|
|
</para>
|
|
<para>
|
|
<parameter>params</parameter> supplies a function for minifying the texture as one of the
|
|
following:
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_NEAREST</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Returns the value of the texture element that is nearest
|
|
(in Manhattan distance)
|
|
to the specified texture coordinates.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GL_LINEAR</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Returns the weighted average of the four texture elements
|
|
that are closest to the specified texture coordinates.
|
|
These can include items wrapped or repeated from other parts of a texture,
|
|
depending on the values of <constant>GL_TEXTURE_WRAP_S</constant> and <constant>GL_TEXTURE_WRAP_T</constant>,
|
|
and on the exact mapping.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GL_NEAREST_MIPMAP_NEAREST</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Chooses the mipmap that most closely matches the size of the pixel
|
|
being textured and uses the <constant>GL_NEAREST</constant> criterion
|
|
(the texture element closest to the specified texture coordinates)
|
|
to produce a texture value.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GL_LINEAR_MIPMAP_NEAREST</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Chooses the mipmap that most closely matches the size of the pixel
|
|
being textured and uses the <constant>GL_LINEAR</constant> criterion
|
|
(a weighted average of the four texture elements that are closest to the specified texture coordinates)
|
|
to produce a texture value.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GL_NEAREST_MIPMAP_LINEAR</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Chooses the two mipmaps that most closely match the size of the pixel
|
|
being textured and uses the <constant>GL_NEAREST</constant> criterion
|
|
(the texture element closest to the specified texture coordinates )
|
|
to produce a texture value from each mipmap.
|
|
The final texture value is a weighted average of those two values.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GL_LINEAR_MIPMAP_LINEAR</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Chooses the two mipmaps that most closely match the size of the pixel
|
|
being textured and uses the <constant>GL_LINEAR</constant> criterion
|
|
(a weighted average of the texture elements that are closest to the specified texture coordinates)
|
|
to produce a texture value from each mipmap.
|
|
The final texture value is a weighted average of those two values.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
<para>
|
|
As more texture elements are sampled in the minification process,
|
|
fewer aliasing artifacts will be apparent.
|
|
While the <constant>GL_NEAREST</constant> and <constant>GL_LINEAR</constant> minification functions can be
|
|
faster than the other four,
|
|
they sample only one or multiple texture elements to determine the texture value
|
|
of the pixel being rendered and can produce moire patterns
|
|
or ragged transitions.
|
|
The initial value of <constant>GL_TEXTURE_MIN_FILTER</constant> is
|
|
<constant>GL_NEAREST_MIPMAP_LINEAR</constant>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_MAG_FILTER</constant></term>
|
|
<listitem>
|
|
<para>
|
|
The texture magnification function is used whenever the level-of-detail function
|
|
used when sampling from the texture determines that the texture should be magified.
|
|
It sets the texture magnification function to either <constant>GL_NEAREST</constant>
|
|
or <constant>GL_LINEAR</constant> (see below). <constant>GL_NEAREST</constant> is generally faster
|
|
than <constant>GL_LINEAR</constant>,
|
|
but it can produce textured images with sharper edges
|
|
because the transition between texture elements is not as smooth.
|
|
The initial value of <constant>GL_TEXTURE_MAG_FILTER</constant> is <constant>GL_LINEAR</constant>.
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_NEAREST</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Returns the value of the texture element that is nearest
|
|
(in Manhattan distance)
|
|
to the specified texture coordinates.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GL_LINEAR</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Returns the weighted average of the texture elements
|
|
that are closest to the specified texture coordinates.
|
|
These can include items wrapped or repeated from other parts of a texture,
|
|
depending on the values of <constant>GL_TEXTURE_WRAP_S</constant> and <constant>GL_TEXTURE_WRAP_T</constant>,
|
|
and on the exact mapping.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_MIN_LOD</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the minimum level-of-detail parameter. This floating-point value
|
|
limits the selection of highest resolution mipmap (lowest mipmap
|
|
level). The initial value is -1000.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_MAX_LOD</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the maximum level-of-detail parameter. This floating-point value
|
|
limits the selection of the lowest resolution mipmap (highest mipmap
|
|
level). The initial value is 1000.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_MAX_LEVEL</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the index of the highest defined mipmap level. This is an integer
|
|
value. The initial value is 1000.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_SWIZZLE_R</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the swizzle that will be applied to the <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
|
|
component of a texel before it is returned to the shader. Valid values for <parameter>param</parameter> are <constant>GL_RED</constant>,
|
|
<constant>GL_GREEN</constant>, <constant>GL_BLUE</constant>, <constant>GL_ALPHA</constant>, <constant>GL_ZERO</constant> and
|
|
<constant>GL_ONE</constant>.
|
|
If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_RED</constant>, the value for
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be taken from the first
|
|
channel of the fetched texel.
|
|
If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_GREEN</constant>, the value for
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be taken from the second
|
|
channel of the fetched texel.
|
|
If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_BLUE</constant>, the value for
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be taken from the third
|
|
channel of the fetched texel.
|
|
If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_ALPHA</constant>, the value for
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be taken from the fourth
|
|
channel of the fetched texel.
|
|
If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_ZERO</constant>, the value for
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be subtituted with
|
|
<inlineequation><mml:math><mml:mn>0.0</mml:mn></mml:math></inlineequation>.
|
|
If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_ONE</constant>, the value for
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be subtituted with
|
|
<inlineequation><mml:math><mml:mn>1.0</mml:mn></mml:math></inlineequation>.
|
|
The initial value is <constant>GL_RED</constant>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_SWIZZLE_G</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the swizzle that will be applied to the <inlineequation><mml:math><mml:mi mathvariant="italic">g</mml:mi></mml:math></inlineequation>
|
|
component of a texel before it is returned to the shader. Valid values for <parameter>param</parameter> and their effects are similar to
|
|
those of <constant>GL_TEXTURE_SWIZZLE_R</constant>.
|
|
The initial value is <constant>GL_GREEN</constant>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_SWIZZLE_B</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the swizzle that will be applied to the <inlineequation><mml:math><mml:mi mathvariant="italic">b</mml:mi></mml:math></inlineequation>
|
|
component of a texel before it is returned to the shader. Valid values for <parameter>param</parameter> and their effects are similar to
|
|
those of <constant>GL_TEXTURE_SWIZZLE_R</constant>.
|
|
The initial value is <constant>GL_BLUE</constant>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_SWIZZLE_A</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the swizzle that will be applied to the <inlineequation><mml:math><mml:mi mathvariant="italic">a</mml:mi></mml:math></inlineequation>
|
|
component of a texel before it is returned to the shader. Valid values for <parameter>param</parameter> and their effects are similar to
|
|
those of <constant>GL_TEXTURE_SWIZZLE_R</constant>.
|
|
The initial value is <constant>GL_ALPHA</constant>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_SWIZZLE_RGBA</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the swizzles that will be applied to the
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>,
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">g</mml:mi></mml:math></inlineequation>,
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">b</mml:mi></mml:math></inlineequation>, and
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">a</mml:mi></mml:math></inlineequation>
|
|
components of a texel before they are returned to the shader. Valid values for <parameter>params</parameter> and their effects are similar to
|
|
those of <constant>GL_TEXTURE_SWIZZLE_R</constant>, except that all channels are specified simultaneously.
|
|
Setting the value of <constant>GL_TEXTURE_SWIZZLE_RGBA</constant> is equivalent (assuming no errors are generated) to
|
|
setting the parameters of each of <constant>GL_TEXTURE_SWIZZLE_R</constant>,
|
|
<constant>GL_TEXTURE_SWIZZLE_G</constant>,
|
|
<constant>GL_TEXTURE_SWIZZLE_B</constant>, and
|
|
<constant>GL_TEXTURE_SWIZZLE_A</constant> successively.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_WRAP_S</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the wrap parameter for texture coordinate
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
|
|
to either <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_CLAMP_TO_BORDER</constant>,
|
|
<constant>GL_MIRRORED_REPEAT</constant>, or
|
|
<constant>GL_REPEAT</constant>. <constant>GL_CLAMP_TO_EDGE</constant> causes
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
|
|
coordinates to be clamped to the
|
|
range
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: left [ {1 over 2N}, 1 - {1 over 2N} right ]: -->
|
|
<mml:mfenced open="[" close="]">
|
|
<mml:mfenced open="" close="">
|
|
<mml:mrow>
|
|
<mml:mfrac>
|
|
<mml:mn>1</mml:mn>
|
|
<mml:mn>2<mml:mi mathvariant="italic">N</mml:mi></mml:mn>
|
|
</mml:mfrac>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
<mml:mrow>
|
|
<mml:mn>1</mml:mn>
|
|
<mml:mo>-</mml:mo>
|
|
<mml:mfenced open="" close="">
|
|
<mml:mrow>
|
|
<mml:mfrac>
|
|
<mml:mn>1</mml:mn>
|
|
<mml:mn>2<mml:mi mathvariant="italic">N</mml:mi></mml:mn>
|
|
</mml:mfrac>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:mfenced>
|
|
</mml:math></inlineequation>,
|
|
where
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">N</mml:mi></mml:math></inlineequation>
|
|
is the size
|
|
of the texture in the direction of clamping.
|
|
<constant>GL_CLAMP_TO_BORDER</constant> evaluates <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> coordinates in a similar manner to <constant>GL_CLAMP_TO_EDGE</constant>.
|
|
However, in cases where clamping would have occurred in <constant>GL_CLAMP_TO_EDGE</constant> mode, the fetched texel data
|
|
is substituted with the values specified by <constant>GL_TEXTURE_BORDER_COLOR</constant>.
|
|
<constant>GL_REPEAT</constant> causes the
|
|
integer part of the
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
|
|
coordinate to be ignored; the GL uses only the
|
|
fractional part, thereby creating a repeating pattern.
|
|
<constant>GL_MIRRORED_REPEAT</constant> causes the
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
|
|
coordinate to be set to the
|
|
fractional part of the texture coordinate if the integer part of
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
|
|
is
|
|
even; if the integer part of
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
|
|
is odd, then the
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
|
|
texture coordinate is
|
|
set to
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: 1 - frac(s): -->
|
|
<mml:mrow>
|
|
<mml:mn>1</mml:mn>
|
|
<mml:mo>-</mml:mo>
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">frac</mml:mi>
|
|
<mml:mo>⁡</mml:mo>
|
|
<mml:mfenced open="(" close=")">
|
|
<mml:mi mathvariant="italic">s</mml:mi>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>,
|
|
where
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: frac(s): -->
|
|
<mml:mrow>
|
|
<mml:mi mathvariant="italic">frac</mml:mi>
|
|
<mml:mo>⁡</mml:mo>
|
|
<mml:mfenced open="(" close=")">
|
|
<mml:mi mathvariant="italic">s</mml:mi>
|
|
</mml:mfenced>
|
|
</mml:mrow>
|
|
</mml:math></inlineequation>
|
|
represents the fractional part of
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>.
|
|
Initially, <constant>GL_TEXTURE_WRAP_S</constant> is set to <constant>GL_REPEAT</constant>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_WRAP_T</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the wrap parameter for texture coordinate
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">t</mml:mi></mml:math></inlineequation>
|
|
to either <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_CLAMP_TO_BORDER</constant>,
|
|
<constant>GL_MIRRORED_REPEAT</constant>, or
|
|
<constant>GL_REPEAT</constant>. See the discussion under <constant>GL_TEXTURE_WRAP_S</constant>.
|
|
Initially, <constant>GL_TEXTURE_WRAP_T</constant> is set to <constant>GL_REPEAT</constant>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GL_TEXTURE_WRAP_R</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the wrap parameter for texture coordinate
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
|
|
to either <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_CLAMP_TO_BORDER</constant>,
|
|
<constant>GL_MIRRORED_REPEAT</constant>, or
|
|
<constant>GL_REPEAT</constant>. See the discussion under <constant>GL_TEXTURE_WRAP_S</constant>.
|
|
Initially, <constant>GL_TEXTURE_WRAP_R</constant> is set to <constant>GL_REPEAT</constant>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
<refsect1 id="notes"><title>Notes</title>
|
|
<para>
|
|
Suppose that a program attempts to sample from a texture and
|
|
has set <constant>GL_TEXTURE_MIN_FILTER</constant> to one of the functions that requires a
|
|
mipmap. If either the dimensions of the texture images currently defined
|
|
(with previous calls to <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>, or <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>) do not
|
|
follow the proper sequence for mipmaps (described above), or there are
|
|
fewer texture images defined than are needed, or the set of texture images
|
|
have differing numbers of texture components, then the texture is considered <emphasis>incomplete</emphasis>.
|
|
</para>
|
|
<para>
|
|
Linear filtering accesses the four nearest texture elements only in 2D
|
|
textures. In 1D textures, linear filtering accesses the two nearest
|
|
texture elements. In 3D textures, linear filtering accesses the eight nearest
|
|
texture elements.
|
|
</para>
|
|
<para>
|
|
<function>glTexParameter</function> specifies the texture parameters for the active texture unit, specified
|
|
by calling <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>.
|
|
</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
|
|
one of the accepted defined values.
|
|
</para>
|
|
<para>
|
|
<constant>GL_INVALID_ENUM</constant> is generated if <parameter>params</parameter> should have a defined
|
|
constant value (based on the value of <parameter>pname</parameter>) and does not.
|
|
</para>
|
|
</refsect1>
|
|
<refsect1 id="associatedgets"><title>Associated Gets</title>
|
|
<para>
|
|
<citerefentry><refentrytitle>glGetTexParameter</refentrytitle></citerefentry>
|
|
</para>
|
|
<para>
|
|
<citerefentry><refentrytitle>glGetTexLevelParameter</refentrytitle></citerefentry>
|
|
</para>
|
|
</refsect1>
|
|
<refsect1 id="seealso"><title>See Also</title>
|
|
<para>
|
|
<citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glBindTexture</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glPixelStore</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glSamplerParameter</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glTexSubImage1D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glTexSubImage2D</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>glTexSubImage3D</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>
|