Attachment 113563 Details for Bug 67676 – version three

version three

EGL_MESA_transparent_alpha.txt (text/plain), 2.96 KB, created by Jonny Lamb on 2015-02-17 11:56:04 UTC

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Creator: Jonny Lamb

Created: 2015-02-17 11:56:04 UTC

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>Name
>
>    EGL_MESA_transparent_alpha
>
>Name Strings
>
>    EGL_MESA_transparent_alpha
>
>Contributors
>
>    Jonny Lamb <jonny.lamb@collabora.co.uk>
>
>Contacts
>
>    Jonny Lamb <jonny.lamb@collabora.co.uk>
>
>Status
>
>    Draft
>
>Version
>
>    Version 3, 2015-02-17
>
>Number
>
>    EGL Extension #XXX
>
>Extension Type
>
>    EGL display extension
>
>Dependencies
>
>    This extension is written against the wording of the 2014.08.17 revision
>    of the EGL 1.5 Specification.
>
>Overview
>
>    This extension defines how to create EGL window surfaces which respect
>    their alpha channels.
>
>New Types
>
>    None
>
>New Procedures and Functions
>
>    None
>
>New Tokens
>
>    Accepted as the value of the EGLConfig attribute EGL_TRANSPARENT_TYPE:
>
>        EGL_TRANSPARENT_ALPHA_MESA                0xXXXX
>
>Additions to the EGL 1.5 Specification
>
>    In section 3.4 "Configuration Management", under the "Other EGLConfig
>    Attribute Descriptions" heading, append to the paragraph which begins with
>    "EGL_TRANSPARENT_TYPE indicates" and ends with "and
>    EGL_TRANSPARENT_BLUE_VALUE, respectively" the following:
>
>    "If the attribute is EGL_TRANSPARENT_ALPHA_MESA then window
>    surfaces created with the EGLConfig will have their alpha channel
>    respected with pre-multiplied alpha implied. Creating non-window
>    surfaces with the EGLConfig will result in an error."
>
>    In the next paragraph replace the first sentence with:
>
>    "If EGL_TRANSPARENT_TYPE is either EGL_NONE or
>    EGL_TRANSPARENT_ALPHA_MESA, then the values for
>    EGL_TRANSPARENT_RED_VALUE, EGL_TRANSPARENT_GREEN_VALUE, and
>    EGL_TRANSPARENT_BLUE_VALUE are undefined."
>
>    Before the paragraph which begins with "EGL_MAX_PBUFFER_WIDTH and
>    EGL_MAX_PBUFFER_HEIGHT indicate" insert the following paragraph:
>
>    "If EGL_TRANSPARENT_TYPE is EGL_TRANSPARENT_ALPHA_MESA and
>    EGL_ALPHA_SIZE is 0, window surfaces created with the EGLConfig
>    will be fully opaque, as if alpha were set to 1.0."
>
>New Behavior
>
>    To determine if the EGL implementation supports this extension, clients
>    should query the EGL_EXTENSIONS string of the current active display.
>
>    To obtain an EGL window surface with a meaningful alpha channel,
>    use an EGLConfig with EGL_TRANSPARENT_TYPE set to
>    EGL_TRANSPARENT_ALPHA_MESA.
>
>Issues
>
>    1. Should non-window surfaces created with EGL_TRANSPARENT_TYPE
>       set to EGL_TRANSPARENT_ALPHA_MESA generate an error or have no
>       effect on the surface?
>
>       RESOLUTION: Yes. Non-window surfaces created with
>       EGL_TRANSPARENT_TYPE set to EGL_TRANSPARENT_ALPHA_MESA will
>       generate an error.
>
>Revision History
>
>    Version 3, 2015-02-17 (Jonny Lamb)
>        - Added pre-multiplied alpha implication.
>
>    Version 2, 2015-02-16 (Jonny Lamb)
>        - Resolved issue #1 to "Yes".
>        - Changed extension type to "display extension" and removed
>          dependency on EGL_EXT_client_extensions.
>        - Added MESA suffix to the new token.
>
>    Version 1, 2014-12-15 (Jonny Lamb)
>        - Initial draft
>
># vim:ai:et:sw=4:ts=4:

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Attachments on bug 67676: 93777 | 94274 | 111864 | 113529 | 113561 | 113563 | 113752 | 144608 | 144609 | 144610 | 144758

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