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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
+ "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
+<refentry id="glGetTexImage">
+ <refmeta>
+ <refmetainfo>
+ <copyright>
+ <year>1991-2006</year>
+ <holder>Silicon Graphics, Inc.</holder>
+ </copyright>
+ </refmetainfo>
+ <refentrytitle>glGetTexImage</refentrytitle>
+ <manvolnum>3G</manvolnum>
+ </refmeta>
+ <refnamediv>
+ <refname>glGetTexImage</refname>
+ <refpurpose>return a texture image</refpurpose>
+ </refnamediv>
+ <refsynopsisdiv><title>C Specification</title>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>void <function>glGetTexImage</function></funcdef>
+ <paramdef>GLenum <parameter>target</parameter></paramdef>
+ <paramdef>GLint <parameter>level</parameter></paramdef>
+ <paramdef>GLenum <parameter>format</parameter></paramdef>
+ <paramdef>GLenum <parameter>type</parameter></paramdef>
+ <paramdef>GLvoid * <parameter>img</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+ <!-- eqn: ignoring delim $$ -->
+ <refsect1 id="parameters"><title>Parameters</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>target</parameter></term>
+ <listitem>
+ <para>
+ Specifies which texture is to be obtained.
+ <constant>GL_TEXTURE_1D</constant>,
+ <constant>GL_TEXTURE_2D</constant>,
+ <constant>GL_TEXTURE_3D</constant>,
+ <constant>GL_TEXTURE_1D_ARRAY</constant>,
+ <constant>GL_TEXTURE_2D_ARRAY</constant>,
+ <constant>GL_TEXTURE_RECTANGLE</constant>,
+ <constant>GL_TEXTURE_CUBE_MAP_POSITIVE_X</constant>,
+ <constant>GL_TEXTURE_CUBE_MAP_NEGATIVE_X</constant>,
+ <constant>GL_TEXTURE_CUBE_MAP_POSITIVE_Y</constant>,
+ <constant>GL_TEXTURE_CUBE_MAP_NEGATIVE_Y</constant>,
+ <constant>GL_TEXTURE_CUBE_MAP_POSITIVE_Z</constant>, and
+ <constant>GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</constant>
+ are accepted.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>level</parameter></term>
+ <listitem>
+ <para>
+ Specifies the level-of-detail number of the desired image.
+ Level 0 is the base image level.
+ Level
+ <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>
+ is the
+ <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>th
+ mipmap reduction image.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>format</parameter></term>
+ <listitem>
+ <para>
+ Specifies a pixel format for the returned data.
+ The supported formats are
+ <constant>GL_STENCIL_INDEX</constant>,
+ <constant>GL_DEPTH_COMPONENT</constant>,
+ <constant>GL_DEPTH_STENCIL</constant>,
+ <constant>GL_RED</constant>,
+ <constant>GL_GREEN</constant>,
+ <constant>GL_BLUE</constant>,
+ <constant>GL_RG</constant>,
+ <constant>GL_RGB</constant>,
+ <constant>GL_RGBA</constant>,
+ <constant>GL_BGR</constant>,
+ <constant>GL_BGRA</constant>,
+ <constant>GL_RED_INTEGER</constant>,
+ <constant>GL_GREEN_INTEGER</constant>,
+ <constant>GL_BLUE_INTEGER</constant>,
+ <constant>GL_RG_INTEGER</constant>,
+ <constant>GL_RGB_INTEGER</constant>,
+ <constant>GL_RGBA_INTEGER</constant>,
+ <constant>GL_BGR_INTEGER</constant>,
+ <constant>GL_BGRA_INTEGER</constant>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>type</parameter></term>
+ <listitem>
+ <para>
+ Specifies a pixel type for the returned data.
+ The supported types are
+ <constant>GL_UNSIGNED_BYTE</constant>,
+ <constant>GL_BYTE</constant>,
+ <constant>GL_UNSIGNED_SHORT</constant>,
+ <constant>GL_SHORT</constant>,
+ <constant>GL_UNSIGNED_INT</constant>,
+ <constant>GL_INT</constant>,
+ <constant>GL_HALF_FLOAT</constant>,
+ <constant>GL_FLOAT</constant>,
+ <constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
+ <constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
+ <constant>GL_UNSIGNED_SHORT_5_6_5</constant>,
+ <constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>,
+ <constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
+ <constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
+ <constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
+ <constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
+ <constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
+ <constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
+ <constant>GL_UNSIGNED_INT_10_10_10_2</constant>,
+ <constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>,
+ <constant>GL_UNSIGNED_INT_24_8</constant>,
+ <constant>GL_UNSIGNED_INT_10F_11F_11F_REV</constant>,
+ <constant>GL_UNSIGNED_INT_5_9_9_9_REV</constant>, and
+ <constant>GL_FLOAT_32_UNSIGNED_INT_24_8_REV</constant>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>img</parameter></term>
+ <listitem>
+ <para>
+ Returns the texture image.
+ Should be a pointer to an array of the type specified by <parameter>type</parameter>.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1 id="description"><title>Description</title>
+ <para>
+ <function>glGetTexImage</function> returns a texture image into <parameter>img</parameter>.
+ <parameter>target</parameter> specifies whether the desired texture image is one specified by
+ <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry> (<constant>GL_TEXTURE_1D</constant>),
+ <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry> (<constant>GL_TEXTURE_1D_ARRAY</constant>, <constant>GL_TEXTURE_RECTANGLE</constant>,
+ <constant>GL_TEXTURE_2D</constant> or any of
+ <constant>GL_TEXTURE_CUBE_MAP_*</constant>),
+ or
+ <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry> (<constant>GL_TEXTURE_2D_ARRAY</constant>,
+ <constant>GL_TEXTURE_3D</constant>).
+ <parameter>level</parameter> specifies the level-of-detail number of the desired image.
+ <parameter>format</parameter> and <parameter>type</parameter> specify the format and type of the desired image array.
+ See the reference page for <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>
+ for a description of the acceptable values for the <parameter>format</parameter> and <parameter>type</parameter>
+ parameters, respectively.
+ </para>
+ <para>
+ If a non-zero named buffer object is bound to the <constant>GL_PIXEL_PACK_BUFFER</constant> target
+ (see <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>) while a texture image is
+ requested, <parameter>img</parameter> is treated as a byte offset into the buffer object's data store.
+ </para>
+ <para>
+ To understand the operation of <function>glGetTexImage</function>, consider the selected internal
+ four-component texture image to be an RGBA color buffer the size of the image.
+ The semantics of <function>glGetTexImage</function> are then identical to those of <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>,
+ with the exception that no pixel transfer operations are performed,
+ when called with the same <parameter>format</parameter> and <parameter>type</parameter>,
+ with <emphasis>x</emphasis> and <emphasis>y</emphasis> set to 0,
+ <emphasis>width</emphasis> set to the width of the texture image
+ and <emphasis>height</emphasis> set to 1 for 1D images,
+ or to the height of the texture image
+ for 2D images.
+ </para>
+ <para>
+ If the selected texture image does not contain four components,
+ the following mappings are applied.
+ Single-component textures are treated as RGBA buffers with red set
+ to the single-component value,
+ green set to 0, blue set to 0, and alpha set to 1.
+ Two-component textures are treated as RGBA buffers with red set to
+ the value of component zero,
+ alpha set to the value of component one,
+ and green and blue set to 0.
+ Finally,
+ three-component textures are treated as RGBA buffers with red set to
+ component zero,
+ green set to component one,
+ blue set to component two,
+ and alpha set to 1.
+ </para>
+ <para>
+ To determine the required size of <parameter>img</parameter>,
+ use <citerefentry><refentrytitle>glGetTexLevelParameter</refentrytitle></citerefentry> to determine the dimensions of the
+ internal texture image,
+ then scale the required number of pixels by the storage required for
+ each pixel,
+ based on <parameter>format</parameter> and <parameter>type</parameter>.
+ Be sure to take the pixel storage parameters into account,
+ especially <constant>GL_PACK_ALIGNMENT</constant>.
+ </para>
+ </refsect1>
+ <refsect1 id="notes"><title>Notes</title>
+ <para>
+ If an error is generated,
+ no change is made to the contents of <parameter>img</parameter>.
+ </para>
+ <para>
+ <function>glGetTexImage</function> returns the texture image for the active texture unit.
+ </para>
+ </refsect1>
+ <refsect1 id="errors"><title>Errors</title>
+ <para>
+ <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter>, <parameter>format</parameter>, or <parameter>type</parameter> is not
+ an accepted value.
+ </para>
+ <para>
+ <constant>GL_INVALID_VALUE</constant> is generated if <parameter>level</parameter> is less than 0.
+ </para>
+ <para>
+ <constant>GL_INVALID_VALUE</constant> may be generated if <parameter>level</parameter> is greater
+ than
+ <inlineequation><mml:math>
+ <!-- eqn: log sub 2 (max): -->
+ <mml:mrow>
+ <mml:msub><mml:mi mathvariant="italic">log</mml:mi>
+ <mml:mn>2</mml:mn>
+ </mml:msub>
+ <mml:mo>⁡</mml:mo>
+ <mml:mfenced open="(" close=")">
+ <mml:mi mathvariant="italic">max</mml:mi>
+ </mml:mfenced>
+ </mml:mrow>
+ </mml:math></inlineequation>,
+ where
+ <inlineequation><mml:math><mml:mi mathvariant="italic">max</mml:mi></mml:math></inlineequation>
+ is the returned value of <constant>GL_MAX_TEXTURE_SIZE</constant>.
+ </para>
+ <para>
+ <constant>GL_INVALID_OPERATION</constant> is returned if <parameter>type</parameter> is one of
+ <constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
+ <constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
+ <constant>GL_UNSIGNED_SHORT_5_6_5</constant>,
+ <constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>, or
+ <constant>GL_UNSIGNED_INT_10F_11F_11F_REV</constant> and <parameter>format</parameter> is not <constant>GL_RGB</constant>.
+ </para>
+ <para>
+ <constant>GL_INVALID_OPERATION</constant> is returned if <parameter>type</parameter> is one of
+ <constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
+ <constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
+ <constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
+ <constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
+ <constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
+ <constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
+ <constant>GL_UNSIGNED_INT_10_10_10_2</constant>,
+ <constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>, or
+ <constant>GL_UNSIGNED_INT_5_9_9_9_REV</constant> and <parameter>format</parameter> is neither <constant>GL_RGBA</constant>
+ or <constant>GL_BGRA</constant>.
+ </para>
+ <para>
+ <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
+ <constant>GL_PIXEL_PACK_BUFFER</constant> target and the buffer object's data store is currently mapped.
+ </para>
+ <para>
+ <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
+ <constant>GL_PIXEL_PACK_BUFFER</constant> target and the data would be packed to the buffer
+ object such that the memory writes required would exceed the data store size.
+ </para>
+ <para>
+ <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
+ <constant>GL_PIXEL_PACK_BUFFER</constant> target and <parameter>img</parameter> is not evenly divisible
+ into the number of bytes needed to store in memory a datum indicated by <parameter>type</parameter>.
+ </para>
+ </refsect1>
+ <refsect1 id="associatedgets"><title>Associated Gets</title>
+ <para>
+ <citerefentry><refentrytitle>glGetTexLevelParameter</refentrytitle></citerefentry> with argument <constant>GL_TEXTURE_WIDTH</constant>
+ </para>
+ <para>
+ <citerefentry><refentrytitle>glGetTexLevelParameter</refentrytitle></citerefentry> with argument <constant>GL_TEXTURE_HEIGHT</constant>
+ </para>
+ <para>
+ <citerefentry><refentrytitle>glGetTexLevelParameter</refentrytitle></citerefentry> with argument <constant>GL_TEXTURE_INTERNAL_FORMAT</constant>
+ </para>
+ <para>
+ <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with arguments <constant>GL_PACK_ALIGNMENT</constant> and others
+ </para>
+ <para>
+ <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_PACK_BUFFER_BINDING</constant>
+ </para>
+ </refsect1>
+ <refsect1 id="seealso"><title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glReadPixels</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>,
+ <citerefentry><refentrytitle>glTexParameter</refentrytitle></citerefentry>
+ </para>
+ </refsect1>
+ <refsect1 id="Copyright"><title>Copyright</title>
+ <para>
+ Copyright <trademark class="copyright"></trademark> 1991-2006
+ Silicon Graphics, Inc. Copyright <trademark class="copyright"></trademark> 2010
+ Khronos Group. This document is licensed under the SGI
+ Free Software B License. For details, see
+ <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
+ </para>
+ </refsect1>
+</refentry>
HCoop / clinton / guile-figl.git / blobdiff