glCompressedTexImage1D.xml

<!DOCTYPE refentry [ <!ENTITY % mathent SYSTEM "math.ent"> %mathent; ]>

<!-- Converted by db4-upgrade version 1.1 -->

<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glCompressedTexImage1D">
    <info>
        <copyright>
            <year>1991-2006</year>
            <holder>Silicon Graphics, Inc.</holder>
        </copyright>
        <copyright>
            <year>2011-2013</year>
            <holder>Khronos Group</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glCompressedTexImage1D</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glCompressedTexImage1D</refname>
        <refpurpose>specify a one-dimensional texture image in a compressed format</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glCompressedTexImage1D</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>GLint <parameter>border</parameter></paramdef>
                <paramdef>GLsizei <parameter>imageSize</parameter></paramdef>
                <paramdef>const GLvoid * <parameter>data</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>target</parameter></term>
            <listitem>
                <para>
                    Specifies the target texture.
                    Must be <constant>GL_TEXTURE_1D</constant> or <constant>GL_PROXY_TEXTURE_1D</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 texture images that are at least 64 texels wide. The height of the 1D texture image is 1.
                </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 xml:id="description"><title>Description</title>
        <para>
            Texturing allows elements of an image array to be read by shaders.
        </para>
        <para>
            <function>glCompressedTexImage1D</function> loads a previously defined, and retrieved, compressed
            one-dimensional texture image if <parameter>target</parameter> is <constant>GL_TEXTURE_1D</constant>
            (see <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>).
        </para>
        <para>
            If <parameter>target</parameter> is <constant>GL_PROXY_TEXTURE_1D</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 an extension-specified compressed-texture format.
            When a texture is loaded with
            <citerefentry><refentrytitle>glTexImage1D</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>glCompressedTexImage1D</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>glTexImage1D</refentrytitle></citerefentry>.
            In the following description, denote by
            <inlineequation>
                <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>s</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation>,
            <inlineequation>
                <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation>,
            <inlineequation>
                <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math>
            </inlineequation>,
            <inlineequation>
                <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><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 xmlns:mml="http://www.w3.org/1998/Math/MathML" display="block" overflow="scroll">
                  <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:mrow>
                </mml:math>
            </inlineequation>
        </para>
    </refsect1>
    <refsect1 xml:id="errors"><title>Errors</title>
        <para>
          <constant>GL_INVALID_ENUM</constant> is generated if <parameter>internalformat</parameter> is not
          a supported specific compressed internal formats, or is one of the generic
          compressed internal formats:
          <constant>GL_COMPRESSED_RED</constant>,
          <constant>GL_COMPRESSED_RG</constant>,
          <constant>GL_COMPRESSED_RGB</constant>,
          <constant>GL_COMPRESSED_RGBA</constant>.
          <constant>GL_COMPRESSED_SRGB</constant>, or
          <constant>GL_COMPRESSED_SRGB_ALPHA</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 xml: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_NUM_COMPRESSED_TEXTURE_FORMATS</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_COMPRESSED_TEXTURE_FORMATS</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 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCompressedTexImage2D</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>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>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 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 1991-2006 Silicon Graphics, Inc.
            Copyright <trademark class="copyright"/> 2011-2013 Khronos Group.
            This document is licensed under the SGI
            Free Software B License. For details, see
            <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</link>.
        </para>
    </refsect1>
</refentry>