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lizheng
213 lines
11 KiB
XML
Executable File
213 lines
11 KiB
XML
Executable File
<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:base="" xml:id="eglCreateContext">
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<info>
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<copyright>
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<year>2003-2018</year>
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<holder>The Khronos Group Inc.</holder>
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</copyright>
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</info>
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<refmeta>
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<refentrytitle>eglCreateContext</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>eglCreateContext</refname>
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<refpurpose>
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create a new <acronym>EGL</acronym> rendering context
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</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>EGLContext <function>eglCreateContext</function></funcdef>
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<paramdef>EGLDisplay <parameter>display</parameter></paramdef>
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<paramdef>EGLConfig <parameter>config</parameter></paramdef>
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<paramdef>EGLContext <parameter>share_context</parameter></paramdef>
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<paramdef>EGLint const * <parameter>attrib_list</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1 xml:id="parameters"><title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><parameter>display</parameter></term>
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<listitem><para>
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Specifies the
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<acronym>EGL</acronym>
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display connection.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>config</parameter></term>
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<listitem><para>Specifies the EGL frame buffer configuration that
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defines the frame buffer resource available to the rendering context.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>share_context</parameter></term>
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<listitem><para>
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Specifies another
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<acronym>EGL</acronym>
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rendering context with which to share data, as
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defined by the client API corresponding to the
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contexts. Data is also shared with all other
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contexts with which
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<parameter>share_context</parameter> shares data.
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<constant>EGL_NO_CONTEXT</constant> indicates that
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no sharing is to take place.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>attrib_list</parameter></term>
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<listitem><para>
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Specifies attributes and attribute values for the
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context being created. Only the attribute
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<constant>EGL_CONTEXT_CLIENT_VERSION</constant> may
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be specified.
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</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 xml:id="description"><title>Description</title>
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<para>
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<function>eglCreateContext</function> creates an EGL
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rendering context for the current rendering API (as set with
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<function>eglBindAPI</function>) and returns a handle to the
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context. The context can then be used to render into an EGL
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drawing surface. If <function>eglCreateContext</function>
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fails to create a rendering context,
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<constant>EGL_NO_CONTEXT</constant> is returned.
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</para>
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<para>
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If <parameter>share_context</parameter> is not
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<constant>EGL_NO_CONTEXT</constant>, then all shareable data
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in the context (as defined by the client API specification
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for the current rendering API) are shared by context
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<parameter>share_context</parameter>, all other contexts
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<parameter>share_context</parameter> already shares with,
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and the newly created context. An arbitrary number of
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rendering contexts can share data. However, all rendering
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contexts that share data must themselves exist in the same
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address space. Two rendering contexts share an address space
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if both are owned by a single process.
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</para>
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<para>
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<parameter>attrib_list</parameter> specifies a list of
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attributes for the context. The list has the same structure
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as described for <function>eglChooseConfig</function>. The
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attributes and attribute values which may be specified are
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as follows:
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</para>
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<variablelist>
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<varlistentry>
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<term><constant>EGL_CONTEXT_MAJOR_VERSION</constant></term>
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<listitem><para>
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Must be followed by an integer specifying the requested
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major version of an OpenGL or OpenGL ES context. The
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default value is 1. This attribute is an alias of the
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older <constant>EGL_CONTEXT_CLIENT_VERSION</constant>,
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and the tokens may be used interchangeably.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EGL_CONTEXT_MINOR_VERSION</constant></term>
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<listitem><para>
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Must be followed by an integer specifying the requested
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minor version of an OpenGL or OpenGL ES context. The
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default value is 0.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EGL_CONTEXT_OPENGL_PROFILE_MASK</constant></term>
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<listitem><para>
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Must be followed by an integer bitmask specifying the
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<firstterm>profile</firstterm> of an OpenGL context.
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Bits which may be set include
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<constant>EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT</constant>
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for a core profile and
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<constant>EGL_CONTEXT_OPENGL_COMPATIBILITY_PROFILE_BIT</constant>
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for a compatibility profile. The default value is
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<constant>EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT</constant>.
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All OpenGL 3.2 and later implementations are required to
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implement the core profile, but implementation of the
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compatibility profile is optional.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EGL_CONTEXT_OPENGL_DEBUG</constant></term>
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<listitem><para>
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Must be followed by <constant>EGL_TRUE</constant>,
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specifying that an OpenGL or OpenGL ES <firstterm>debug
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context</firstterm> should be created, or
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<constant>EGL_FALSE</constant>, if a non-debug context
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should be created. The default value is
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<constant>EGL_FALSE</constant>.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE</constant></term>
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<listitem><para>
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Must be followed by <constant>EGL_TRUE</constant>,
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specifying that a
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<firstterm>forward-compatible</firstterm> OpenGL context
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should be created, or <constant>EGL_FALSE</constant>, if
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a non-forward-compatible context should be created. The
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default value is <constant>EGL_FALSE</constant>.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EGL_CONTEXT_OPENGL_ROBUST_ACCESS</constant></term>
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<listitem><para>
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Must be followed by <constant>EGL_TRUE</constant>,
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specifying that an OpenGL or OpenGL ES context
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supporting <firstterm>robust buffer access</firstterm>
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should be created, or <constant>EGL_FALSE</constant>, if
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a non-robust context should be created. The default
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value is <constant>EGL_FALSE</constant>.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY</constant></term>
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<listitem><para>
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Must be followed by
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<constant>EGL_LOSE_CONTEXT_ON_RESET</constant>,
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specifying that an OpenGL or OpenGL ES context with
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reset notification behavior
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<constant>GL_LOSE_CONTEXT_ON_RESET_ARB</constant> should
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be created, or
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<constant>EGL_NO_RESET_NOTIFICATION</constant>,
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specifying that an OpenGL or OpenGL ES context with
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reset notification behavior
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<constant>GL_NO_RESET_NOTIFICATION_ARB</constant> should
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be created, as described by the
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<constant>GL_ARB_robustness</constant> extension.
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</para><para>
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If the
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<constant>EGL_CONTEXT_OPENGL_ROBUST_ACCESS</constant>
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attribute is not set to <constant>EGL_TRUE</constant>,
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context creation will not fail, but the resulting
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context may not support robust buffer access, and
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therefore may not support the requested reset
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notification strategy The default value for
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<constant>EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY</constant>
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is <constant>EGL_NO_RESET_NOTIFICATION</constant> .
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</para></listitem>
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</varlistentry>
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</variablelist>
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<para>
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There are many possible interactions between requested OpenGL
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and OpenGL ES context creation attributes, depending on the API
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versions and extensions supported by the implementation. These
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interactions are described in detail in the EGL 1.5
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Specification, but are not listed here for compactness. The
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requested attributes may not be able to be satisfied, but
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context creation may still succeed. Applications should ensure
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that the OpenGL or OpenGL ES contexts supports needed features
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before using them, by determining the actual context version,
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supported extensions, and supported context flags using runtime
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queries.
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</para>
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</refsect1>
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</refentry>
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