Opentk/Source/Bind/Specifications/Docs/ES20/glCopyTexImage2D.xml
2014-03-28 20:06:55 +01:00

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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="glCopyTexImage2D">
<refmeta>
<refmetainfo>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
</refmetainfo>
<refentrytitle>glCopyTexImage2D</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glCopyTexImage2D</refname>
<refpurpose>copy pixels into a 2D texture image</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glCopyTexImage2D</function></funcdef>
<paramdef>GLenum <parameter>target</parameter></paramdef>
<paramdef>GLint <parameter>level</parameter></paramdef>
<paramdef>GLenum <parameter>internalformat</parameter></paramdef>
<paramdef>GLint <parameter>x</parameter></paramdef>
<paramdef>GLint <parameter>y</parameter></paramdef>
<paramdef>GLsizei <parameter>width</parameter></paramdef>
<paramdef>GLsizei <parameter>height</parameter></paramdef>
<paramdef>GLint <parameter>border</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<!-- eqn: ignoring delim $$ -->
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>target</parameter></term>
<listitem>
<para>
Specifies the target texture of the active texture unit.
Must be <constant>GL_TEXTURE_2D</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>, or
<constant>GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</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 internal format of the texture.
Must be one of the following symbolic constants:
<constant>GL_ALPHA</constant>,
<constant>GL_LUMINANCE</constant>,
<constant>GL_LUMINANCE_ALPHA</constant>,
<constant>GL_RGB</constant>, or
<constant>GL_RGBA</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>x</parameter></term>
<term><parameter>y</parameter></term>
<listitem>
<para>
Specify the window coordinates of the lower left corner
of the rectangular region of pixels to be copied.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>width</parameter></term>
<listitem>
<para>
Specifies the width of the texture image.
All implementations support 2D texture images that are at least 64 texels
wide and cube-mapped texture images that are at least 16 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 images that are at least 64 texels
high and cube-mapped texture images that are at least 16 texels high.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>border</parameter></term>
<listitem>
<para>
Specifies the width of the border.
Must be 0.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para>
Texturing maps a portion of a specified texture image
onto each graphical primitive for which texturing is
active. Texturing is active when the current fragment shader or
vertex shader makes use of built-in texture lookup
functions.
</para>
<para>
<function>glCopyTexImage2D</function> defines a two-dimensional texture image or cube-map texture image
with pixels from the current framebuffer (rather than from
client memory, as is the case for <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>).
</para>
<para>
The screen-aligned pixel rectangle with lower left corner at (<parameter>x</parameter>,
<parameter>y</parameter>) and with a width of <parameter>width</parameter>
and a height of <parameter>height</parameter>
defines the texture array
at the mipmap level specified by <parameter>level</parameter>.
<parameter>internalformat</parameter> specifies the internal format of the texture array.
</para>
<para>
The pixels in the rectangle are processed exactly as if
<citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry> had been called with
<parameter>format</parameter> set to <constant>GL_RGBA</constant>, but the process stops just after
conversion of RGBA values. Subsequent processing is identical to that
described for <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
beginning with the clamping of the R, G, B, and A values to the range
<inlineequation><mml:math>
<!-- eqn: [0,1]:-->
<mml:mfenced open="[" close="]">
<mml:mn>0</mml:mn>
<mml:mn>1</mml:mn>
</mml:mfenced>
</mml:math></inlineequation>
and then conversion to the texture's internal format for storage in the texel
array.
</para>
<para>
The components required for <parameter>internalformat</parameter> must be a subset of
those present in the framebuffer's format. For example, a <constant>GL_RGBA</constant>
framebuffer can be used to supply components for any <parameter>internalformat</parameter>.
However, a <constant>GL_RGB</constant> framebuffer can only be used to supply components for
<constant>GL_RGB</constant> or <constant>GL_LUMINANCE</constant> base internal format textures,
not <constant>GL_ALPHA</constant>, <constant>GL_LUMINANCE_ALPHA</constant>, or
<constant>GL_RGBA</constant> textures.
</para>
<para>
Pixel ordering is such that lower
<inlineequation><mml:math><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation>
and
<inlineequation><mml:math><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation>
screen coordinates correspond to
lower
<inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
and
<inlineequation><mml:math><mml:mi mathvariant="italic">t</mml:mi></mml:math></inlineequation>
texture coordinates.
</para>
<para>
If any of the pixels within the specified rectangle are outside the framebuffer associated with the current
rendering context, then the values obtained for those pixels are undefined.
</para>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para>
A GL implementation may choose to store the texture
array at any internal resolution it chooses.
</para>
<para>
An image with height or width of 0 indicates a NULL texture.
</para>
<para>
<function>glCopyTexImage2D</function>
specifies a two-dimensional or cube-map texture for the current texture unit,
specified with <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>.
</para>
</refsect1>
<refsect1 id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not <constant>GL_TEXTURE_2D</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>, or
<constant>GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</constant>.
</para>
<para>
<constant>GL_INVALID_ENUM</constant> is generated if <parameter>internalformat</parameter> is not an
accepted format.
</para>
<para>
<constant>GL_INVALID_VALUE</constant> is generated if <parameter>target</parameter> is one of the six cube map 2D image targets and the width and height parameters are not equal.
</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>&it;</mml:mo>
<mml:mi mathvariant="italic">max</mml:mi>
</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> when <parameter>target</parameter>
is <constant>GL_TEXTURE_2D</constant> or <constant>GL_MAX_CUBE_MAP_TEXTURE_SIZE</constant> when
<parameter>target</parameter> is not <constant>GL_TEXTURE_2D</constant>.
</para>
<para>
<constant>GL_INVALID_VALUE</constant> is generated if <parameter>width</parameter> or <parameter>height</parameter> is less than 0
or greater than <constant>GL_MAX_TEXTURE_SIZE</constant> when <parameter>target</parameter>
is <constant>GL_TEXTURE_2D</constant> or <constant>GL_MAX_CUBE_MAP_TEXTURE_SIZE</constant> when
<parameter>target</parameter> is not <constant>GL_TEXTURE_2D</constant>.
</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
the currently bound framebuffer's format does not contain a superset of
the components required by the base format of <parameter>internalformat</parameter>.
</para>
<para>
<constant>GL_INVALID_FRAMEBUFFER_OPERATION</constant> is generated if
the currently bound framebuffer is not framebuffer complete (i.e. the
return value from <citerefentry><refentrytitle>glCheckFramebufferStatus</refentrytitle></citerefentry>
is not <constant>GL_FRAMEBUFFER_COMPLETE</constant>).
</para>
</refsect1>
<refsect1 id="associatedgets"><title>Associated Gets</title>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry>
with argument <constant>GL_MAX_TEXTURE_SIZE</constant> or
<constant>GL_MAX_CUBE_MAP_TEXTURE_SIZE</constant>
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glCheckFramebufferStatus</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glCompressedTexImage2D</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glCompressedTexSubImage2D</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glTexParameter</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glTexSubImage2D</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 id="copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"></trademark> 1991-2006
Silicon Graphics, Inc. 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>