kc3-lang/angle/extensions/ANGLE_request_extension.txt

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• Author : Geoff Lang
  Date : 2016-11-29 10:37:36
  Hash : c339c4e5
  Message : Split WebGL compatibility into two extensions. The mechanism for requesting extensions is now a separate extension. Added a way to query the extensions that support enabling. BUG=angleproject:1523 Change-Id: I2efaa9f6d67b12ecae325f455404e34ba04d0e7c Reviewed-on: https://chromium-review.googlesource.com/414529 Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>

• extensions/ANGLE_request_extension.txt

• Name
  
      ANGLE_request_extension
  
  Name Strings
  
      GL_ANGLE_request_extension
  
  Contributors
  
      Geoff Lang
  
  Contact
  
      Geoff Lang (geofflang 'at' google.com)
  
  Notice
  
      Copyright (c) 2016 The Khronos Group Inc. Copyright terms at
          http://www.khronos.org/registry/speccopyright.html
  
  Status
  
      Draft
  
  Version
  
      Version 1, November 28, 2016
  
  Number
  
      OpenGL ES Extension #??
  
  Dependencies
  
      Requires OpenGL ES 2.0
  
      Written against the OpenGL ES 3.0 specification.
  
  Overview
  
      This extension allows the client to query extensions that can be enabled and
      explicitly request than an extension be enabled.
  
  New Procedures and Functions
  
      void RequestExtension(const char *name)
  
  New Tokens
  
      Accepted by the <name> parameter of GetString and GetStringi:
  
          REQUESTABLE_EXTENSIONS_ANGLE      0x93A8
  
      Accepted by the <value> parameter of the GetInteger* functions:
  
          NUM_REQUESTABLE_EXTENSIONS_ANGLE  0x93A9
  
  Additions to the OpenGL ES 3.0 Specification
  
      Add the following paragraph to the end paragraph 4 of section 6.1.6, String
      Queries:
  
      "REQUESTABLE_EXTENSIONS_ANGLE returns a list of extensions that can be
      enabled at runtime by calling RequestExtension."
  
      Change the following section of paragraph 6 of section 6.1.6, String Queries:
  
      - "name may only be EXTENSIONS, indicating that the extension name
      - corresponding to the indexth supported extension should be returned.
      - <index> may range from zero to the value of NUM_EXTENSIONS minus one"
      + "name may be EXTENSIONS or REQUESTABLE_EXTENSIONS_ANGLE, indicating that
      + the extension name corresponding to the indexth supported or requestable
      + extension should be returned. <index> may range from zero to the value of
      + NUM_EXTENSIONS and NUM_REQUESTABLE_EXTENSIONS_ANGLE minus one"
  
      The command
  
         void RequestExtension(const char *name)
  
      enables the requestable OpenGL ES extension named <name>. If the extension
      was not requestable, INVALID_OPERATION is generated.
  
  New State
  
      Add to Table 6.30 (Implementation Dependent Version and Extension Support)
  
      Get value                        Type Get Cmd     Min Value Description                      Sec.
      -------------------------------- ---- ----------- --------- -------------------------------- -----
      NUM_REQUESTABLE_EXTENSIONS_ANGLE Z+   GetIntegerv -         Number of individual requestable 6.1.6
                                                                  extension names
  
  Interactions with the OpenGL ES 2.0 specification:
  
      Remove all references to GetStringi and NUM_REQUESTABLE_EXTENSIONS_ANGLE.
  
  Issues
  
      (1) How can the user determine which extensions can be enabled without
          potentially generating errors?
  
        This can be solved by:
        a) Never generate an error in EnableExtensions, simply return false when
           the extension is not recognized or cannot be enabled.
        b) Add another query for the extensions that the context supports
           enabling.
  
        RESOLVED: Use (b) because it allows the context to explicity advertise
        which extensions support enabling and doesn't generate errors in the
        normal use case.
  
  Revision History
  
      Rev.    Date         Author     Changes
      ----  -------------  ---------  ----------------------------------------
        1    Nov 28, 2016  geofflang  Initial version