kc3-lang/angle/extensions/EGL_ANGLE_surface_orientation.txt

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  Commit

• Author : Geoff Lang
  Date : 2015-12-16 13:31:57
  Hash : 7f448b58
  Message : Add an EGL_ANGLE_surface_orientation extension. BUG=angleproject:1262 Change-Id: Ifbb0f5302311a68a0c6f02baaea706cbb7055a52 Reviewed-on: https://chromium-review.googlesource.com/320011 Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>

• extensions/EGL_ANGLE_surface_orientation.txt

• Name
  
      ANGLE_surface_orientation
  
  Name Strings
  
      EGL_ANGLE_surface_orientation
  
  Contributors
  
      Geoff Lang, Google
  
  Contacts
  
      Geoff Lang, Google (geofflang 'at' google 'dot' com)
  
  Status
  
      Draft
  
  Version
  
      Version 1, 2015-12-15
  
  Number
  
      EGL Extension XXX
  
  Extension Type
  
      EGL display extension
  
  Dependencies
  
      Written based on the wording of the EGL 1.5 Specification
      (August 7 2014).
  
  Overview
  
      This extension provides a mechanism for querying the most optimal
      orientation of a window surface and creating window sufraces with
      non-default orientations for the most performant rendering.
  
  New Types
  
      None
  
  New Procedures and Functions
  
      None
  
  New Tokens
  
      New EGLConfig bitmask attribute name:
  
          EGL_OPTIMAL_SURFACE_ORIENTATION_ANGLE 0x33A7
  
      Accepted as an attribute name in the <attrib_list> argument of
      eglCreateWindowSurface and attribute name in the <attribute>
      argument of eglQuerySurface:
  
          EGL_SURFACE_ORIENTATION_ANGLE 0x33A8
  
      Valid bitfields in the EGL_OPTIMAL_SURFACE_ORIENTATION_ANGLE bitmask
      attribute of EGLConfig and EGL_SURFACE_ORIENTATION_ANGLE bitmask attribute
      of eglCreateWindowSurface:
  
          EGL_SURFACE_ORIENTATION_INVERT_X_ANGLE 0x0001
          EGL_SURFACE_ORIENTATION_INVERT_Y_ANGLE 0x0002
  
  Additions to the EGL Specification
  
      Additions to Chapter 3 of the EGL 1.5 Specification (EGL Functions and Errors)
  
      Add to table 3.1 (EGLConfig Attributes)
  
      Attribute                              Type     Notes
      -------------------------------------  -------  ----------------------
      EGL_OPTIMAL_SURFACE_ORIENTATION_ANGLE  bitmask  Optimal window surface
                                                      orientation.
  
  
      Add a paragraph to section 3.4, section Other EGLConfig Attribute
      Descriptions.
  
      "EGL_OPTIMAL_SURFACE_ORIENTATION_ANGLE is a mask indicating which
      window surface orientation will provide the best performance."
  
      Add to table 3.4 (Default values and match criteria for EGLConfig
      attributes):
  
      Attribute                              Default  Selection  Sort     Sort
                                                      Criteria   Order    Priority
      -------------------------------------  -------  ---------  -------  --------
      EGL_OPTIMAL_SURFACE_ORIENTATION_ANGLE  0        Exact      None
  
      Add a paragraph to section 3.5.1, section Creating On-Screen Rendering
      Surfaces.
  
      EGL_SURFACE_ORIENTATION_ANGLE attribute specifies how the surface's content
      will appear on the screen. If its value contains
      EGL_SURFACE_ORIENTATION_INVERT_X_ANGLE then all displayed content will be
      inverted along the vertical axis. Similarly, if its value contains
      EGL_SURFACE_ORIENTATION_INVERT_Y_ANGLE then all displayed content will be
      inverted along the horizontal axis.
  
      Add to table 3.5 (Queryable surface attributes and types):
  
      Attribute                      Type     Description
      -----------------------------  -------  ----------------------
      EGL_SURFACE_ORIENTATION_ANGLE  bitmask  Orientation of surface
  
      Add a paragraph to section 3.5.6, Surface Attributes:
  
      "Querying EGL_SURFACE_ORIENTATION_ANGLE returns the orientation of the
      surface.  For a window surface, this is the same attribute value specified
      when the surface was created.  For other types of surfaces, it is always
      0."
  
  Issues
  
      1) What about dirty regions and sub regions specified by extensions such as
         NV_post_sub_buffer?
  
         These regions will be applied to the same region of the window as
         before because they are often specified based on events from the
         operating system.  The content in these regions will be displayed
         according to the value of EGL_SURFACE_ORIENTATION_ANGLE.
  
  Revision History
  
      Version 1, 2015-12-15 (Geoff Lang)
        - Initial draft