Name

eglCreateContext — create a new EGL rendering context

C Specification

EGLContext eglCreateContext( EGLDisplay display,
  EGLConfig config,
  EGLContext share_context,
  EGLint const * attrib_list);
 

Parameters

display

Specifies the EGL display connection.

config

Specifies the EGL frame buffer configuration that defines the frame buffer resource available to the rendering context.

share_context

Specifies another EGL rendering context with which to share data, as defined by the client API corresponding to the contexts. Data is also shared with all other contexts with which share_context shares data. EGL_NO_CONTEXT indicates that no sharing is to take place.

attrib_list

Specifies attributes and attribute values for the context being created.

Description

eglCreateContext creates an EGL rendering context for the current rendering API (as set with eglBindAPI) and returns a handle to the context. The context can then be used to render into an EGL drawing surface. If eglCreateContext fails to create a rendering context, EGL_NO_CONTEXT is returned.

If share_context is not EGL_NO_CONTEXT, then all shareable data in the context (as defined by the client API specification for the current rendering API) are shared by context share_context, all other contexts share_context already shares with, and the newly created context. An arbitrary number of rendering contexts can share data. However, all rendering contexts that share data must themselves exist in the same address space. Two rendering contexts share an address space if both are owned by a single process.

attrib_list specifies a list of attributes for the context. The list has the same structure as described for eglChooseConfig. The attributes and attribute values which may be specified are as follows:

EGL_CONTEXT_MAJOR_VERSION

Must be followed by an integer specifying the requested major version of an OpenGL or OpenGL ES context. The default value is 1. This attribute is an alias of the older EGL_CONTEXT_CLIENT_VERSION, and the tokens may be used interchangeably.

EGL_CONTEXT_MINOR_VERSION

Must be followed by an integer specifying the requested minor version of an OpenGL or OpenGL ES context. The default value is 0.

EGL_CONTEXT_OPENGL_PROFILE_MASK

Must be followed by an integer bitmask specifying the profile of an OpenGL context. Bits which may be set include EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT for a core profile and EGL_CONTEXT_OPENGL_COMPATIBILITY_PROFILE_BIT for a compatibility profile. The default value is EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT. All OpenGL 3.2 and later implementations are required to implement the core profile, but implementation of the compatibility profile is optional.

EGL_CONTEXT_OPENGL_DEBUG

Must be followed by EGL_TRUE, specifying that an OpenGL or OpenGL ES debug context should be created, or EGL_FALSE, if a non-debug context should be created. The default value is EGL_FALSE.

EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE

Must be followed by EGL_TRUE, specifying that a forward-compatible OpenGL context should be created, or EGL_FALSE, if a non-forward-compatible context should be created. The default value is EGL_FALSE.

EGL_CONTEXT_OPENGL_ROBUST_ACCESS

Must be followed by EGL_TRUE, specifying that an OpenGL or OpenGL ES context supporting robust buffer access should be created, or EGL_FALSE, if a non-robust context should be created. The default value is EGL_FALSE.

EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY

Must be followed by EGL_LOSE_CONTEXT_ON_RESET, specifying that an OpenGL or OpenGL ES context with reset notification behavior GL_LOSE_CONTEXT_ON_RESET_ARB should be created, or EGL_NO_RESET_NOTIFICATION, specifying that an OpenGL or OpenGL ES context with reset notification behavior GL_NO_RESET_NOTIFICATION_ARB should be created, as described by the GL_ARB_robustness extension.

If the EGL_CONTEXT_OPENGL_ROBUST_ACCESS attribute is not set to EGL_TRUE, context creation will not fail, but the resulting context may not support robust buffer access, and therefore may not support the requested reset notification strategy The default value for EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY is EGL_NO_RESET_NOTIFICATION .

There are many possible interactions between requested OpenGL and OpenGL ES context creation attributes, depending on the API versions and extensions supported by the implementation. These interactions are described in detail in the EGL 1.5 Specification, but are not listed here for compactness. The requested attributes may not be able to be satisfied, but context creation may still succeed. Applications should ensure that the OpenGL or OpenGL ES contexts supports needed features before using them, by determining the actual context version, supported extensions, and supported context flags using runtime queries.