EXT_platform_device

Name

EXT_platform_device

Name Strings

EGL_EXT_platform_device

Contributors

James Jones
Daniel Kartch
  

Contacts

James Jones, NVIDIA  (jajones 'at' nvidia.com)

Status

Complete

Version

Version 6 - May 16th, 2014

Number

EGL Extension #73

Extension Type

EGL device extension

Dependencies

Requires EGL_EXT_device_base

Requires EGL_EXT_platform_base or EGL 1.5

Written against the wording of EGL 1.5

Overview

Increasingly, EGL and its client APIs are being used in place of
"native" rendering APIs to implement the basic graphics
functionality of native windowing systems.  This creates demand
for a method to initialize EGL displays and surfaces directly on
top of native GPU or device objects rather than native window
system objects.  The mechanics of enumerating the underlying
native devices and constructing EGL displays and surfaces from
them have been solved in various platform and implementation-
specific ways.  The EGL device family of extensions offers a
standardized framework for bootstrapping EGL without the use of
any underlying "native" APIs or functionality.

This extension defines a method to create an EGLDisplay from an
EGLDeviceEXT by treating the EGLDeviceEXT as an EGLNativeDisplay
object.
  

New Types

None

New Functions

None

New Tokens

Accepted by the <platform> parameter of eglGetPlatformDisplayEXT
and eglGetPlatformDisplay:

    EGL_PLATFORM_DEVICE_EXT                  0x313F
  

Replace the last paragraph of section 2.1 "Native Window System and Rendering APIs"

"This specification defines only the EGLDeviceEXT platform, and
behavior specific to it.  Implementations may support other
platforms, but their existence and behavior is defined by
extensions.  To detect support for other platforms, clients should
query the EGL_EXTENSIONS string of EGL_NO_DISPLAY using
eglQueryString (see section 3.3).
  

Replace the second sentence of the paragraph following the eglGetPlatformDisplay prototype

"The only valid value for <platform> is EGL_PLATFORM_DEVICE_EXT.
When <platform> is EGL_PLATFORM_DEVICE_EXT, <native_display> must
be an EGLDeviceEXT object.  Platform-specific extensions may
define other valid values for <platform>."
  

Add the following sentence to the end of the second paragraph after the eglCreatePlatformWindowSurface prototype.

"There are no valid values of <native_window> when <dpy> belongs
to the EGL_PLATFORM_DEVICE_EXT platform."
  

Add the following sentence to the end of the second paragraph after the eglCreatePlatformPixmapSurface prototype.

"There are no valid values of <native_pixmap> when <dpy> belongs
to the EGL_PLATFORM_DEVICE_EXT platform.
  

Issues

1.  Do EGLDevice-backed displays support window or pixmap surfaces?
    If so, what native objects are they associated with?  If not,
    are EGLDevice-backed displays useful in any way?

    RESOLVED: This extension defines no method to create window or
    pixmap surfaces on the EGLDeviceEXT platform.  Other
    extensions may define such functionality.  Presumably, if
    there are no other extensions that expose native window or
    pixmap types associated with EGL devices, EGLDeviceEXT-backed
    displays could expose EGLConfigs that only support rendering
    to EGLStreamKHR or EGLPbuffer surfaces.

2.  Should the EGL_PLATFORM_DEVICE_EXT platform be included in the
    EGL specification as a special "blessed" platform, or exist
    only as an extension like other platforms?

    RESOLVED: EGL devices are defined as part of the EGL
    specification, so there's no reason to exclude their
    associated platform from the core EGL specification.  They are
    not native objects, therefore they can not be referred to as a
    native platform, even though they are used interchangeably
    with native objects in this extension.
  

Revision History:

#6  (May 16th, 2014) James Jones
    - Marked the extension complete
    - Marked all issues resolved

#5  (April 8th, 2014) James Jones
    - Updated wording based on the EGL 1.5 spec
    - Assigned values to tokens

#4  (November 6th, 2013) James Jones
    - Specified this is a device extension
    - Requires, rather than interacts with EGL_EXT_platform_base
    - Removed EGL_SUPPORTS_PLATFORM_DEVICE_EXT.  There is no need
      for a separate query now that the name string is listed in
      the per-device extension string

#3  (April 23rd, 2013) James Jones
    - Fixed minor typos

#2  (April 18th, 2013) James Jones
    - Moved eglGetDisplayPointerEXT to a stand-alone extension
    - Renamed from EGL_EXT_device_display to
      EGL_EXT_platform_device
    - Filled in the actual spec language modifications
    - Replaced issue 2, since the original was moved to
      EGL_EXT_display_attributes
    - Reworded issue 1.
    - Fixed some typos

#1  (April 16th, 2013) James Jones
    - Initial Draft
  