Opentk/Source/Bind/Specifications/Docs/ES20/glCheckFramebufferStatus.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="glCheckFramebufferStatus">
<refmeta>
<refmetainfo>
<copyright>
<year>2005</year>
<holder>Sams Publishing</holder>
</copyright>
</refmetainfo>
<refentrytitle>glCheckFramebufferStatus</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glCheckFramebufferStatus</refname>
<refpurpose>return the framebuffer completeness status of a framebuffer object</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>GLenum <function>glCheckFramebufferStatus</function></funcdef>
<paramdef>GLenum <parameter>target</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>target</parameter></term>
<listitem>
<para>
Specifies the target framebuffer object.
The symbolic constant must be <constant>GL_FRAMEBUFFER</constant>.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para>
<function>glCheckFramebufferStatus</function> returns a symbolic
constant that identifies whether or not the currently bound
framebuffer is framebuffer complete, and if not, which of the rules
of framebuffer completeness is violated.
</para>
<para>
If the framebuffer is complete, then
<constant>GL_FRAMEBUFFER_COMPLETE</constant> is returned.
If the framebuffer is not complete, the return values are as follows:
</para>
<variablelist>
<varlistentry>
<term><constant>GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT</constant></term>
<listitem>
<para>
Not all framebuffer attachment points are framebuffer
attachment complete. This means that at least one
attachment point with a renderbuffer or texture
attached has its attached object no longer in existence
or has an attached image with a width or height of
zero, or the color attachment point has a
non-color-renderable image attached, or the
depth attachment point has a non-depth-renderable
image attached, or the stencil attachment point has a
non-stencil-renderable image attached.
</para>
<para>
Color-renderable formats include <constant>GL_RGBA4</constant>,
<constant>GL_RGB5_A1</constant>, and
<constant>GL_RGB565</constant>.
<constant>GL_DEPTH_COMPONENT16</constant> is the only
depth-renderable format.
<constant>GL_STENCIL_INDEX8</constant> is the only
stencil-renderable format.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS</constant></term>
<listitem>
<para>
Not all attached images have the same width and height.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT</constant></term>
<listitem>
<para>
No images are attached to the framebuffer.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_FRAMEBUFFER_UNSUPPORTED</constant></term>
<listitem>
<para>
The combination of internal formats of the attached
images violates an implementation-dependent set of
restrictions.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
If the currently bound framebuffer is not framebuffer complete,
then it is an error to attempt to use the framebuffer for
writing or reading. This means that rendering commands
(<citerefentry><refentrytitle>glClear</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>, and
<citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>)
as well as commands that read the framebuffer
(<citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>, and
<citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>)
will generate the error <constant>GL_INVALID_FRAMEBUFFER_OPERATION</constant>
if called while the framebuffer is not framebuffer complete.
</para>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para>
It is strongly advised, thought not required, that an application
call <function>glCheckFramebufferStatus</function> to see if the
framebuffer is complete prior to rendering. This is because some
implementations may not support rendering to particular combinations
of internal formats. In this case,
<constant>GL_FRAMEBUFFER_UNSUPPORTED</constant>
is returned.
</para>
<para>
The default window-system-provided framebuffer is always
framebuffer complete, and thus <constant>GL_FRAMEBUFFER_COMPLETE</constant>
is returned when <constant>GL_FRAMEBUFFER_BINDING</constant> is 0.
</para>
<para>
Additionally, if an error occurs, zero is returned.
</para>
</refsect1>
<refsect1 id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not <constant>GL_FRAMEBUFFER</constant>.
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>glBindRenderbuffer</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glRenderbufferStorage</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 id="copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"></trademark> 2008 Khronos Group.
This material may be distributed subject to the terms and conditions set forth in
the Open Publication License, v 1.0, 8 June 1999.
<ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
</para>
</refsect1>
</refentry>