Opentk/Source/Bind/Specifications/Docs/ES31/glEnable.xml
2014-03-28 20:06:55 +01:00

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<!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="glEnable">
<info>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
<copyright>
<year>2010-2014</year>
<holder>Khronos Group</holder>
</copyright>
</info>
<refmeta>
<refentrytitle>glEnable</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glEnable</refname>
<refpurpose>enable or disable server-side GL capabilities</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glEnable</function></funcdef>
<paramdef>GLenum <parameter>cap</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glDisable</function></funcdef>
<paramdef>GLenum <parameter>cap</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 xml:id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>cap</parameter></term>
<listitem>
<para>
Specifies a symbolic constant indicating a GL capability.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 xml:id="description"><title>Description</title>
<para>
<function>glEnable</function> and
<citerefentry><refentrytitle>glDisable</refentrytitle></citerefentry>
enable and disable various capabilities. Use
<citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry>
or
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry>
to determine the current setting of any capability. The initial
value for each capability with the exception of
<constant>GL_DITHER</constant> is <constant>GL_FALSE</constant>.
The initial value for <constant>GL_DITHER</constant> is
<constant>GL_TRUE</constant>.
</para>
<para>
Both <function>glEnable</function> and <citerefentry><refentrytitle>glDisable</refentrytitle></citerefentry> take a single argument, <parameter>cap</parameter>,
which can assume one of the following values:
</para>
<variablelist>
<varlistentry>
<term><constant>GL_BLEND</constant></term>
<listitem>
<para>
If enabled,
blend the computed fragment color values with the values in the color
buffers. See <citerefentry><refentrytitle>glBlendFunc</refentrytitle></citerefentry>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_CULL_FACE</constant></term>
<listitem>
<para>
</para>
<para>
If enabled,
cull polygons based on their winding in window coordinates.
See <citerefentry><refentrytitle>glCullFace</refentrytitle></citerefentry>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_DEPTH_TEST</constant></term>
<listitem>
<para>
If enabled,
do depth comparisons and update the depth buffer. Note that even if
the depth buffer exists and the depth mask is non-zero, the
depth buffer is not updated if the depth test is disabled. See
<citerefentry><refentrytitle>glDepthFunc</refentrytitle></citerefentry> and
<citerefentry><refentrytitle>glDepthRangef</refentrytitle></citerefentry>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_DITHER</constant> </term>
<listitem>
<para>
If enabled,
dither color components or indices before they are written to the
color buffer.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_POLYGON_OFFSET_FILL</constant></term>
<listitem>
<para>
If enabled, an offset is added to depth values of a polygon's
fragments before the depth comparison is performed.
See <citerefentry><refentrytitle>glPolygonOffset</refentrytitle></citerefentry>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_PRIMITIVE_RESTART_FIXED_INDEX</constant></term>
<listitem>
<para>
Enables primitive restarting. If enabled, any one of the draw commands
which transfers a set of generic attribute array elements to the GL will restart
the primitive when the index of the vertex is equal to
<inlineequation>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:msup>
<mml:mn>2</mml:mn>
<mml:mi>n</mml:mi>
</mml:msup>
<mml:mo>&minus;</mml:mo>
<mml:mn>1</mml:mn>
</mml:math>
</inlineequation>
where <emphasis>n</emphasis> is 8, 16 or 32 if the type is
<constant>GL_UNSIGNED_BYTE</constant>,
<constant>GL_UNSIGNED_SHORT</constant>, or
<constant>GL_UNSIGNED_INT</constant>, respectively.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_RASTERIZER_DISCARD</constant></term>
<listitem>
<para>
If enabled, primitives are discarded immediately before the rasterization stage,
but after the optional transform feedback stage.
<citerefentry><refentrytitle>glClear</refentrytitle></citerefentry> and
<citerefentry><refentrytitle>glClearBuffer</refentrytitle></citerefentry>* commands
are also ignored.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_SAMPLE_ALPHA_TO_COVERAGE</constant></term>
<listitem>
<para>
If enabled,
compute a temporary coverage value where each bit is determined by the
alpha value at the corresponding sample location. The temporary coverage
value is then ANDed with the fragment coverage value.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_SAMPLE_COVERAGE</constant></term>
<listitem>
<para>
If enabled,
the fragment's coverage is ANDed with the temporary coverage value. If
<constant>GL_SAMPLE_COVERAGE_INVERT</constant> is set to <constant>GL_TRUE</constant>, invert the coverage
value.
See <citerefentry><refentrytitle>glSampleCoverage</refentrytitle></citerefentry>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_SCISSOR_TEST</constant></term>
<listitem>
<para>
If enabled,
discard fragments that are outside the scissor rectangle.
See <citerefentry><refentrytitle>glScissor</refentrytitle></citerefentry>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_STENCIL_TEST</constant></term>
<listitem>
<para>
If enabled,
do stencil testing and update the stencil buffer.
See <citerefentry><refentrytitle>glStencilFunc</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glStencilOp</refentrytitle></citerefentry>.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 xml:id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_ENUM</constant> is generated if <parameter>cap</parameter> is not one of the values
listed previously.
</para>
</refsect1>
<refsect1 xml:id="associatedgets"><title>Associated Gets</title>
<para>
<citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 xml:id="versions">
<title>API Version Support</title>
<informaltable>
<tgroup cols="4" align="left">
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apifunchead.xml" xpointer="xpointer(/*/*)"/>
<tbody>
<row>
<entry><function>glEnable</function></entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='es20']/*)"/>
</row>
<row>
<entry><function>glDisable</function></entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='es20']/*)"/>
</row>
</tbody>
</tgroup>
</informaltable>
</refsect1>
<refsect1 xml:id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>glBlendFunc</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glCullFace</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDepthFunc</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDepthRangef</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glPolygonOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glSampleCoverage</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glScissor</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glStencilFunc</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glStencilOp</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>