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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glGetTexLevelParameter">
  <info>
    <copyright>
      <year>2014</year>

      <holder>Khronos Group</holder>
    </copyright>
  </info>

  <refmeta>
    <refentrytitle>glGetTexLevelParameter</refentrytitle>

    <manvolnum>3G</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>glGetTexLevelParameter</refname>

    <refpurpose>return texture parameter values for a specific level of
    detail</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <title>C Specification</title>

    <funcsynopsis>
      <funcprototype>
        <funcdef>void <function>glGetTexLevelParameterfv</function></funcdef>

        <paramdef>GLenum <parameter>target</parameter></paramdef>

        <paramdef>GLint <parameter>level</parameter></paramdef>

        <paramdef>GLenum <parameter>pname</parameter></paramdef>

        <paramdef>GLfloat * <parameter>params</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>void <function>glGetTexLevelParameteriv</function></funcdef>

        <paramdef>GLenum <parameter>target</parameter></paramdef>

        <paramdef>GLint <parameter>level</parameter></paramdef>

        <paramdef>GLenum <parameter>pname</parameter></paramdef>

        <paramdef>GLint * <parameter>params</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>void <function>glGetTextureLevelParameterfv</function></funcdef>

        <paramdef>GLuint <parameter>texture</parameter></paramdef>

        <paramdef>GLint <parameter>level</parameter></paramdef>

        <paramdef>GLenum <parameter>pname</parameter></paramdef>

        <paramdef>GLfloat *<parameter>params</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>void <function>glGetTextureLevelParameteriv</function></funcdef>

        <paramdef>GLuint <parameter>texture</parameter></paramdef>

        <paramdef>GLint <parameter>level</parameter></paramdef>

        <paramdef>GLenum <parameter>pname</parameter></paramdef>

        <paramdef>GLint *<parameter>params</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1 xml:id="parameters">
    <title>Parameters</title>

    <variablelist>
      <varlistentry>
        <term><parameter>target</parameter></term>

        <listitem>
          <para>Specifies the target to which the texture is bound for
          <function>glGetTexLevelParameterfv</function> and
          <function>glGetTexLevelParameteriv</function> functions. Must be one
          of the following values: <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_2D_MULTISAMPLE</constant>,
          <constant>GL_TEXTURE_2D_MULTISAMPLE_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>,
          <constant>GL_PROXY_TEXTURE_1D</constant>,
          <constant>GL_PROXY_TEXTURE_2D</constant>,
          <constant>GL_PROXY_TEXTURE_3D</constant>,
          <constant>GL_PROXY_TEXTURE_1D_ARRAY</constant>,
          <constant>GL_PROXY_TEXTURE_2D_ARRAY</constant>,
          <constant>GL_PROXY_TEXTURE_RECTANGLE</constant>,
          <constant>GL_PROXY_TEXTURE_2D_MULTISAMPLE</constant>,
          <constant>GL_PROXY_TEXTURE_2D_MULTISAMPLE_ARRAY</constant>,
          <constant>GL_PROXY_TEXTURE_CUBE_MAP</constant>, or
          <constant>GL_TEXTURE_BUFFER</constant>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><parameter>texture</parameter></term>

        <listitem>
          <para>Specifies the texture object name for
          <function>glGetTextureLevelParameterfv</function> and
          <function>glGetTextureLevelParameteriv</function> functions.</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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>
                    is the
                    <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>th
                    mipmap reduction image.
                </para>
            </listitem>
        </varlistentry>

      <varlistentry>
        <term><parameter>pname</parameter></term>

        <listitem>
          <para>Specifies the symbolic name of a texture parameter.
          <constant>GL_TEXTURE_WIDTH</constant>,
          <constant>GL_TEXTURE_HEIGHT</constant>,
          <constant>GL_TEXTURE_DEPTH</constant>,
          <constant>GL_TEXTURE_INTERNAL_FORMAT</constant>,
          <constant>GL_TEXTURE_RED_SIZE</constant>,
          <constant>GL_TEXTURE_GREEN_SIZE</constant>,
          <constant>GL_TEXTURE_BLUE_SIZE</constant>,
          <constant>GL_TEXTURE_ALPHA_SIZE</constant>,
          <constant>GL_TEXTURE_DEPTH_SIZE</constant>,
          <constant>GL_TEXTURE_COMPRESSED</constant>,
          <constant>GL_TEXTURE_COMPRESSED_IMAGE_SIZE</constant>, and
          <constant>GL_TEXTURE_BUFFER_OFFSET</constant> are accepted.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><parameter>params</parameter></term>

        <listitem>
          <para>Returns the requested data.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 xml:id="description">
    <title>Description</title>

    <para><function>glGetTexLevelParameterfv</function>,
    <function>glGetTexLevelParameteriv</function>,
    <function>glGetTextureLevelParameterfv</function> and
    <function>glGetTextureLevelParameteriv</function> return in
    <parameter>params</parameter> texture parameter values for a specific
    level-of-detail value, specified as <parameter>level</parameter>. For the
    first two functions, <parameter>target</parameter> defines the target
    texture, either <constant>GL_TEXTURE_1D</constant>,
    <constant>GL_TEXTURE_2D</constant>, <constant>GL_TEXTURE_3D</constant>,
    <constant>GL_PROXY_TEXTURE_1D</constant>,
    <constant>GL_PROXY_TEXTURE_2D</constant>,
    <constant>GL_PROXY_TEXTURE_3D</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>. The remaining two take a
    <parameter>texture</parameter> argument which specifies the name of the
    texture object.</para>

    <para><constant>GL_MAX_TEXTURE_SIZE</constant>, and
    <constant>GL_MAX_3D_TEXTURE_SIZE</constant> are not really descriptive
    enough. It has to report the largest square texture image that can be
    accommodated with mipmaps but a long skinny texture, or a texture without
    mipmaps may easily fit in texture memory. The proxy targets allow the user
    to more accurately query whether the GL can accommodate a texture of a
    given configuration. If the texture cannot be accommodated, the texture
    state variables, which may be queried with
    <function>glGetTexLevelParameter</function> and
    <function>glGetTextureLevelParameter</function>, are set to 0. If the
    texture can be accommodated, the texture state values will be set as they
    would be set for a non-proxy target.</para>

    <para><parameter>pname</parameter> specifies the texture parameter whose
    value or values will be returned.</para>

    <para>The accepted parameter names are as follows:</para>

    <variablelist>
      <varlistentry>
        <term><constant>GL_TEXTURE_WIDTH</constant></term>

        <listitem>
          <para><parameter>params</parameter> returns a single value, the
          width of the texture image. The initial value is 0.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>GL_TEXTURE_HEIGHT</constant></term>

        <listitem>
          <para><parameter>params</parameter> returns a single value, the
          height of the texture image. The initial value is 0.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>GL_TEXTURE_DEPTH</constant></term>

        <listitem>
          <para><parameter>params</parameter> returns a single value, the
          depth of the texture image. The initial value is 0.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>GL_TEXTURE_INTERNAL_FORMAT</constant></term>

        <listitem>
          <para><parameter>params</parameter> returns a single value, the
          internal format of the texture image.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>GL_TEXTURE_RED_TYPE</constant>,
        <constant>GL_TEXTURE_GREEN_TYPE</constant>,
        <constant>GL_TEXTURE_BLUE_TYPE</constant>,
        <constant>GL_TEXTURE_ALPHA_TYPE</constant>,
        <constant>GL_TEXTURE_DEPTH_TYPE</constant></term>

        <listitem>
          <para>The data type used to store the component. The types
          <constant>GL_NONE</constant>,
          <constant>GL_SIGNED_NORMALIZED</constant>,
          <constant>GL_UNSIGNED_NORMALIZED</constant>,
          <constant>GL_FLOAT</constant>, <constant>GL_INT</constant>, and
          <constant>GL_UNSIGNED_INT</constant> may be returned to indicate
          signed normalized fixed-point, unsigned normalized fixed-point,
          floating-point, integer unnormalized, and unsigned integer
          unnormalized components, respectively.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>GL_TEXTURE_RED_SIZE</constant>,
        <constant>GL_TEXTURE_GREEN_SIZE</constant>,
        <constant>GL_TEXTURE_BLUE_SIZE</constant>,
        <constant>GL_TEXTURE_ALPHA_SIZE</constant>,
        <constant>GL_TEXTURE_DEPTH_SIZE</constant></term>

        <listitem>
          <para/>

          <para>
            The internal storage resolution of an individual component. The
            resolution chosen by the GL will be a close match for the
            resolution requested by the user with the component argument of
            <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>,
            and
            <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>.
            The initial value is 0.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>GL_TEXTURE_COMPRESSED</constant></term>

        <listitem>
          <para/>

          <para><parameter>params</parameter> returns a single boolean value
          indicating if the texture image is stored in a compressed internal
          format. The initiali value is <constant>GL_FALSE</constant>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>GL_TEXTURE_COMPRESSED_IMAGE_SIZE</constant></term>

        <listitem>
          <para/>

          <para>
            <parameter>params</parameter> returns a single integer value,
            the number of unsigned bytes of the compressed texture image
            that would be returned from
            <citerefentry><refentrytitle>glGetCompressedTexImage</refentrytitle></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>GL_TEXTURE_BUFFER_OFFSET</constant></term>

        <listitem>
          <para/>

          <para><parameter>params</parameter> returns a single integer value,
            the offset into the data store of the buffer bound to a buffer
            texture.
            <citerefentry><refentrytitle>glTexBufferRange</refentrytitle></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>GL_TEXTURE_BUFFER_SIZE</constant></term>

        <listitem>
          <para/>

          <para><parameter>params</parameter> returns a single integer value,
            the size of the range of a data store of the buffer bound to a
            buffer texture.
            <citerefentry><refentrytitle>glTexBufferRange</refentrytitle></citerefentry>.
          </para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 xml:id="notes">
    <title>Notes</title>

    <para>If an error is generated, no change is made to the contents of
    <parameter>params</parameter>.</para>

    <para><function>glGetTexLevelParameter</function> returns the texture
    level parameters for the active texture unit.</para>

    <para><constant>GL_TEXTURE_BUFFER_OFFSET</constant> and
    <constant>GL_TEXTURE_BUFFER_SIZE</constant> are available only if the GL
    version is 4.3 or greater.</para>
  </refsect1>

  <refsect1 xml:id="errors">
    <title>Errors</title>

    <para><constant>GL_INVALID_OPERATION</constant> is generated by
    <function>glGetTextureLevelParameterfv</function> and
    <function>glGetTextureLevelParameteriv</function> functions if
    <parameter>texture</parameter> is not the name of an existing texture
    object.</para>

    <para><constant>GL_INVALID_ENUM</constant> is generated by
    <function>glGetTexLevelParameterfv</function> and
    <function>glGetTexLevelParameteriv</function> functions if
    <parameter>target</parameter> or <parameter>pname</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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
          <!-- eqn: log sub 2: -->

          <mml:msub>
            <mml:mi mathvariant="italic">log</mml:mi>

            <mml:mn>2</mml:mn>
          </mml:msub>
        </mml:math>
      </inlineequation> <emphasis>max</emphasis>, where
    <emphasis>max</emphasis> is the returned value of
    <constant>GL_MAX_TEXTURE_SIZE</constant>.</para>

    <para><constant>GL_INVALID_VALUE</constant> is generated if
    <parameter>target</parameter> is <constant>GL_TEXTURE_BUFFER</constant>
    and <parameter>level</parameter> is not zero.</para>

    <para><constant>GL_INVALID_OPERATION</constant> is generated if
    <constant>GL_TEXTURE_COMPRESSED_IMAGE_SIZE</constant> is queried on
    texture images with an uncompressed internal format or on proxy
    targets.</para>
  </refsect1>
    <refsect1 xml:id="versions"><title>Version Support</title>
        <informaltable>
            <tgroup cols="13" align="left">
                <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apifunchead.xml" xpointer="xpointer(/*/*)"/>
                <tbody>
                    <row>
                        <entry><function>glGetTexLevelParameterfv</function></entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='20']/*)"/>
                    </row>
                    <row>
                        <entry><function>glGetTexLevelParameteriv</function></entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='20']/*)"/>
                    </row>
                    <row>
                        <entry><function>glGetTextureLevelParameterfv</function></entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='45']/*)"/>
                    </row>
                    <row>
                        <entry><function>glGetTextureLevelParameteriv</function></entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='45']/*)"/>
                    </row>
                </tbody>
            </tgroup>
        </informaltable>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetTexParameter</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>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 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 1991-2006
            Silicon Graphics, Inc. Copyright <trademark class="copyright"/> 2010-2014
            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>
