Opentk/Source/Bind/Specifications/Docs/GL/glGetTexLevelParameter.xml

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<!DOCTYPE refentry [ <!ENTITY % mathent SYSTEM "math.ent"> %mathent; ]>
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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glGetTexLevelParameter">
<info>
<copyright>
<year>2013</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>
</funcsynopsis>
<funcsynopsis>
<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>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 xml:id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>target</parameter></term>
<listitem>
<para>
Specifies the symbolic name of the target texture,
one of
<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>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>glGetTexLevelParameter</function> returns in <parameter>params</parameter> texture parameter values for a specific
level-of-detail value,
specified as <parameter>level</parameter>.
<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>.
</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>, 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>
<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>
<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>
<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>
<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>
<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_ENUM</constant> is generated 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">
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<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="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"/> 2010-2013
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>