Opentk/Source/Bind/Specifications/Docs/glCompressedTexImage2D.xml

<?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="glCompressedTexImage2D">
    <refentryinfo>
        <copyright>
            <year>1991-2006</year>
            <holder>Silicon Graphics, Inc.</holder>
        </copyright>
        <copyright>
            <year>2011-2013</year>
            <holder>Khronos Group</holder>
        </copyright>
    </refentryinfo>
    <refmeta>
        <refentrytitle>glCompressedTexImage2D</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glCompressedTexImage2D</refname>
        <refpurpose>specify a two-dimensional texture image in a compressed format</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glCompressedTexImage2D</function></funcdef>
                <paramdef>GLenum <parameter>target</parameter></paramdef>
                <paramdef>GLint <parameter>level</parameter></paramdef>
                <paramdef>GLenum <parameter>internalformat</parameter></paramdef>
                <paramdef>GLsizei <parameter>width</parameter></paramdef>
                <paramdef>GLsizei <parameter>height</parameter></paramdef>
                <paramdef>GLint <parameter>border</parameter></paramdef>
                <paramdef>GLsizei <parameter>imageSize</parameter></paramdef>
                <paramdef>const GLvoid * <parameter>data</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>target</parameter></term>
            <listitem>
                <para>
                    Specifies the target texture.
                    Must be <constant>GL_TEXTURE_2D</constant>, <constant>GL_PROXY_TEXTURE_2D</constant>,
                    <constant>GL_TEXTURE_1D_ARRAY</constant>, <constant>GL_PROXY_TEXTURE_1D_ARRAY</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>,
                    <constant>GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</constant>, or
                    <constant>GL_PROXY_TEXTURE_CUBE_MAP</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>level</parameter></term>
            <listitem>
                <para>
                    Specifies the level-of-detail number.
                    Level 0 is the base image level.
                    Level <emphasis>n</emphasis> is the <emphasis>n</emphasis>th mipmap reduction image.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>internalformat</parameter></term>
            <listitem>
                <para>
                    Specifies the format of the compressed image data stored at address <parameter>data</parameter>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>width</parameter></term>
            <listitem>
                <para>
                    Specifies the width of the texture image.
                    All implementations support 2D texture and cube map texture images that are at least 16384 texels wide.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>height</parameter></term>
            <listitem>
                <para>
                    Specifies the height of the texture image.
                    All implementations support 2D texture and cube map texture images that are at least 16384 texels high.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>border</parameter></term>
            <listitem>
                <para>
                    This value must be 0.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>imageSize</parameter></term>
            <listitem>
                <para>
                    Specifies the number of unsigned bytes of image data starting at the
                    address specified by <parameter>data</parameter>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>data</parameter></term>
            <listitem>
                <para>
                    Specifies a pointer to the compressed image data in memory.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            Texturing allows elements of an image array to be read by shaders.
        </para>
        <para>
            <function>glCompressedTexImage2D</function> loads a previously defined, and retrieved, compressed two-dimensional
            texture image if <parameter>target</parameter> is <constant>GL_TEXTURE_2D</constant>, or one of the
            cube map faces such as <constant>GL_TEXTURE_CUBE_MAP_POSITIVE_X</constant>.
            (see <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>).
        </para>
        <para>
            If <parameter>target</parameter> is <constant>GL_TEXTURE_1D_ARRAY</constant>, <parameter>data</parameter>
            is treated as an array of compressed 1D textures.
        </para>
        <para>
            If <parameter>target</parameter> is <constant>GL_PROXY_TEXTURE_2D</constant>, <constant>GL_PROXY_TEXTURE_1D_ARRAY</constant>
            or <constant>GL_PROXY_TEXTURE_CUBE_MAP</constant>, no data is read from <parameter>data</parameter>, but
            all of the texture image state is recalculated, checked for consistency,
            and checked against the implementation's capabilities.  If the
            implementation cannot handle a texture of the requested texture size, it
            sets all of the image state to 0, but does not generate an error (see
            <citerefentry><refentrytitle>glGetError</refentrytitle></citerefentry>). To query for an entire mipmap array,
            use an image array level greater than or equal to 1.
        </para>
        <para>
            <parameter>internalformat</parameter> must be a known compressed image format (such as <constant>GL_RGTC</constant>)
            or an extension-specified compressed-texture format.
            When a texture is loaded with <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry> using a generic compressed
            texture format (e.g., <constant>GL_COMPRESSED_RGB</constant>), the GL selects from one of
            its extensions supporting compressed textures.  In order to load the
            compressed texture image using <function>glCompressedTexImage2D</function>, query the compressed texture image's
            size and format using <citerefentry><refentrytitle>glGetTexLevelParameter</refentrytitle></citerefentry>.
        </para>
        <para>
            If a non-zero named buffer object is bound to the <constant>GL_PIXEL_UNPACK_BUFFER</constant> target 
            (see <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>) while a texture image is
            specified, <parameter>data</parameter> is treated as a byte offset into the buffer object's data store.
        </para>
        <para>
            If the compressed data are arranged into fixed-size blocks of texels, the pixel
            storage modes can be used to select a sub-rectangle from a larger containing rectangle.
            These pixel storage modes operate in the same way as they do for <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>.
            In the following description, denote by 
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>s</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation>,
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation>,
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>h</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation>, and
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>d</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation>,
            the values of pixel storage modes <constant>GL_UNPACK_COMPRESSED_BLOCK_SIZE</constant>,
            <constant>GL_UNPACK_COMPRESSED_BLOCK_WIDTH</constant>, <constant>GL_UNPACK_COMPRESSED_BLOCK_HEIGHT</constant>,
            and <constant>GL_UNPACK_COMPRESSED_BLOCK_DEPTH</constant>, respectively.
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>s</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation> is the compressed block size in bytes; 
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation>,
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>h</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation>, and
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>d</mml:mi></mml:msub></mml:mrow></mml:math> 
            </inlineequation> are the compressed block width, height, and depth in pixels.
        </para>
        <para>
            By default the pixel storage modes <constant>GL_UNPACK_ROW_LENGTH</constant>,
            <constant>GL_UNPACK_SKIP_ROWS</constant>, <constant>GL_UNPACK_SKIP_PIXELS</constant>,
            <constant>GL_UNPACK_IMAGE_HEIGHT</constant> and <constant>GL_UNPACK_SKIP_IMAGES</constant>
            are ignored for compressed images. To enable <constant>GL_UNPACK_SKIP_PIXELS</constant>
            and <constant>GL_UNPACK_ROW_LENGTH</constant>, 
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>s</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation>
            and 
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math> 
            </inlineequation>
            must both be non-zero.
            To also enable <constant>GL_UNPACK_SKIP_ROWS</constant> and <constant>GL_UNPACK_IMAGE_HEIGHT</constant>,
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>h</mml:mi></mml:msub></mml:mrow></mml:math> 
            </inlineequation>
            must be non-zero.
            To also enable <constant>GL_UNPACK_SKIP_IMAGES</constant>, 
            <inlineequation>
                <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>d</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation>
            must be non-zero. All parameters must be consistent with the compressed format to produce the desired results.
        </para>
        <para>
            When selecting a sub-rectangle from a compressed image:
            <itemizedlist>
                <listitem>
                    <para>
                        The value of
                        <constant>GL_UNPACK_SKIP_PIXELS</constant> must be a
                        multiple of 
                        <inlineequation>
                            <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math>
                        </inlineequation>;
                    </para>
                </listitem>
                <listitem>
                    <para>
                        the value of
                        <constant>GL_UNPACK_SKIP_ROWS</constant> must be a
                        multiple of
                        <inlineequation>
                            <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math>
                        </inlineequation>.
                    </para>
                </listitem>
            </itemizedlist>
        </para>
        <para>
            <parameter>imageSize</parameter> must be equal to:
        </para>
        <para>
            <inlineequation>
                <mml:math display = 'block'>
                  <mml:mrow>
                    <mml:msub>
                      <mml:mi>b</mml:mi>
                      <mml:mi>s</mml:mi>
                    </mml:msub>
                    <mml:mo lspace='2px' rspace='2px'>&times;</mml:mo>
                    <mml:mfenced open = '&lceil;' close = '&rceil;'>
                      <mml:mfrac>
                        <mml:mi>width</mml:mi>
                        <mml:msub>
                          <mml:mi>b</mml:mi>
                          <mml:mi>w</mml:mi>
                        </mml:msub>
                      </mml:mfrac>
                    </mml:mfenced>
                    <mml:mo lspace='2px' rspace='2px'>&times;</mml:mo>
                    <mml:mfenced open = '&lceil;' close = '&rceil;'>
                      <mml:mfrac>
                        <mml:mi>height</mml:mi>
                        <mml:msub>
                          <mml:mi>b</mml:mi>
                          <mml:mi>h</mml:mi>
                        </mml:msub>
                      </mml:mfrac>
                    </mml:mfenced>
                  </mml:mrow>
                </mml:math>
            </inlineequation>
        </para>
    </refsect1>
    <refsect1 id="notes"><title>Notes</title>
        <para>
            The specific compressed internal formats <constant>GL_COMPRESSED_RGB8_ETC2</constant>,
          <constant>GL_COMPRESSED_SRGB8_ETC2</constant>,
          <constant>GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2</constant>,
          <constant>GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2</constant>,
          <constant>GL_COMPRESSED_RGBA8_ETC2_EAC</constant>,
          <constant>GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC</constant>,
          <constant>GL_COMPRESSED_R11_EAC</constant>,
          <constant>GL_COMPRESSED_SIGNED_R11_EAC</constant>,
          <constant>GL_COMPRESSED_RG11_EAC</constant>, and
          <constant>GL_COMPRESSED_SIGNED_RG11_EAC</constant> are available only if the GL version
          is 4.3 or higher.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <para>
          <constant>GL_INVALID_ENUM</constant> is generated if <parameter>internalformat</parameter> is not one of the specific
          compressed internal formats:
          <constant>GL_COMPRESSED_RED_RGTC1</constant>,
          <constant>GL_COMPRESSED_SIGNED_RED_RGTC1</constant>,
          <constant>GL_COMPRESSED_RG_RGTC2</constant>,
          <constant>GL_COMPRESSED_SIGNED_RG_RGTC2</constant>.
          <constant>GL_COMPRESSED_RGBA_BPTC_UNORM</constant>,
          <constant>GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM</constant>,
          <constant>GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT</constant>,
          <constant>GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT</constant>,
          <constant>GL_COMPRESSED_RGB8_ETC2</constant>,
          <constant>GL_COMPRESSED_SRGB8_ETC2</constant>,
          <constant>GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2</constant>,
          <constant>GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2</constant>,
          <constant>GL_COMPRESSED_RGBA8_ETC2_EAC</constant>,
          <constant>GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC</constant>,
          <constant>GL_COMPRESSED_R11_EAC</constant>,
          <constant>GL_COMPRESSED_SIGNED_R11_EAC</constant>,
          <constant>GL_COMPRESSED_RG11_EAC</constant>, or
          <constant>GL_COMPRESSED_SIGNED_RG11_EAC</constant>.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>imageSize</parameter> is not consistent with
            the format, dimensions, and contents of the specified compressed image
            data.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>border</parameter> is not 0.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if parameter combinations are not
            supported by the specific compressed internal format as specified in the
            specific texture compression extension.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
            <constant>GL_PIXEL_UNPACK_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_UNPACK_BUFFER</constant> target and the data would be unpacked from the buffer 
            object such that the memory reads required would exceed the data store size.
        </para>
        <para>
            Undefined results, including abnormal program termination, are generated if
            <parameter>data</parameter> is not encoded in a manner consistent with the extension
            specification defining the internal compression format.
        </para>
    </refsect1>
    <refsect1 id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGetCompressedTexImage</refentrytitle></citerefentry>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_TEXTURE_COMPRESSED</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_UNPACK_BUFFER_BINDING</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGetTexLevelParameter</refentrytitle></citerefentry> with arguments <constant>GL_TEXTURE_INTERNAL_FORMAT</constant>
            and <constant>GL_TEXTURE_COMPRESSED_IMAGE_SIZE</constant>
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCompressedTexImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCompressedTexImage3D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCompressedTexSubImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCompressedTexSubImage2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCompressedTexSubImage3D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glPixelStore</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> 2011-2013 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>