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PojavLauncherTeam
GitHub Repository: PojavLauncherTeam/mesa
 Path: blob/21.2-virgl/docs/_extra/specs/EGL_MESA_platform_surfaceless.txt
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Name

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    MESA_platform_surfaceless

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Name Strings

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    EGL_MESA_platform_surfaceless

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Contributors

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    Chad Versace <[email protected]>

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    Haixia Shi <[email protected]>

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    Stéphane Marchesin <[email protected]>

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    Zach Reizner <[email protected]>

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    Gurchetan Singh <[email protected]>

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Contacts

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    Chad Versace <[email protected]>

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Status

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    DRAFT

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Version

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    Version 2, 2016-10-13

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Number

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    EGL Extension #TODO

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Extension Type

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    EGL client extension

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Dependencies

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    Requires EGL 1.5 or later; or EGL 1.4 with EGL_EXT_platform_base.

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    This extension is written against the EGL 1.5 Specification (draft

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    20140122).

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    This extension interacts with EGL_EXT_platform_base as follows. If the

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    implementation supports EGL_EXT_platform_base, then text regarding

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    eglGetPlatformDisplay applies also to eglGetPlatformDisplayEXT;

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    eglCreatePlatformWindowSurface to eglCreatePlatformWindowSurfaceEXT; and

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    eglCreatePlatformPixmapSurface to eglCreatePlatformPixmapSurfaceEXT.

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Overview

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    This extension defines a new EGL platform, the "surfaceless" platform. This

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    platfom's defining property is that it has no native surfaces, and hence

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    neither eglCreatePlatformWindowSurface nor eglCreatePlatformPixmapSurface

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    can be used. The platform is independent of any native window system.

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    The platform's intended use case is for enabling OpenGL and OpenGL ES

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    applications on systems where no window system exists. However, the

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    platform's permitted usage is not restricted to this case.  Since the

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    platform is independent of any native window system, it may also be used on

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    systems where a window system is present.

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New Types

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    None

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New Procedures and Functions

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    None

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New Tokens

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    Accepted as the <platform> argument of eglGetPlatformDisplay:

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        EGL_PLATFORM_SURFACELESS_MESA           0x31DD

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Additions to the EGL Specification

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    None.

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New Behavior

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    To determine if the EGL implementation supports this extension, clients

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    should query the EGL_EXTENSIONS string of EGL_NO_DISPLAY.

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    To obtain an EGLDisplay on the surfaceless platform, call

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    eglGetPlatformDisplay with <platform> set to EGL_PLATFORM_SURFACELESS_MESA.

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    The <native_display> parameter must be EGL_DEFAULT_DISPLAY.

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    eglCreatePlatformWindowSurface fails when called with a <display> that

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    belongs to the surfaceless platform. It returns EGL_NO_SURFACE and

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    generates EGL_BAD_NATIVE_WINDOW. The justification for this unconditional

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    failure is that the surfaceless platform has no native windows, and

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    therefore the <native_window> parameter is always invalid.

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    Likewise, eglCreatePlatformPixmapSurface also fails when called with a

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    <display> that belongs to the surfaceless platform.  It returns

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    EGL_NO_SURFACE and generates EGL_BAD_NATIVE_PIXMAP.

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    The surfaceless platform imposes no platform-specific restrictions on the

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    creation of pbuffers, as eglCreatePbufferSurface has no native surface

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    parameter.  Specifically, if the EGLDisplay advertises an EGLConfig whose

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    EGL_SURFACE_TYPE attribute contains EGL_PBUFFER_BIT, then the EGLDisplay

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    permits the creation of pbuffers with that config.

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Issues

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    None.

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Revision History

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    Version 2, 2016-10-13 (Chad Versace)

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        - Assign enum values

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        - Define interfactions with EGL 1.4 and EGL_EXT_platform_base.

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        - Add Gurchetan as contributor, as he implemented the pbuffer support.

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    Version 1, 2016-09-23 (Chad Versace)

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        - Initial version

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        - Posted for review at

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          https://lists.freedesktop.org/archives/mesa-dev/2016-September/129549.html

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