gpu/GLES2/extensions/CHROMIUM/CHROMIUM_texture_mailbox.txt

Name

    CHROMIUM_texture_mailbox

Name Strings

    GL_CHROMIUM_texture_mailbox

Version

    Last Modifed Date: June 11, 2018

Dependencies

    OpenGL ES 2.0 is required.

Overview

    This extension defines a way of sharing texture image data between texture
    objects in different contexts where the contexts would not normally share
    texture resources. Two new functions are exported.
    glProduceTextureDirectCHROMIUM generates a name that can be used to identify
    texture image data outside the scope of a context group and associates a
    texture object with that global mailbox name.
    glCreateAndConsumeTextureCHROMIUM associates the texture object referenced
    by a mailbox name to a texture name.

New Procedures and Functions

    void glProduceTextureDirectCHROMIUM (GLuint texture, GLbyte *mailbox)

    Generates a unique name identifying a mailbox, and associates the specified
    texture object with the mailbox name. The name is generated using a
    cryptographic random number generator and is intended to be difficult to
    guess. The scope of the name is implementation specific, for example it
    might not span multiple displays.

    A given texture object can be associated with several mailbox names.

    This operation does not change the texture bindings or alter the bound
    texture in any way.

    <texture> Specifies the name of a texture.

    <mailbox> returns a GL_MAILBOX_SIZE_CHROMIUM byte sized name.

    INVALID_OPERATION is generated if <texture> is not a valid texture.


    GLuint glCreateAndConsumeTextureCHROMIUM (const GLbyte *mailbox)

    Returns a new texture name pointing to the texture object associated with
    the mailbox name. Does not alter the texture bindings or alter the currently
    bound texture in any way. All the contexts that have consumed the texture
    object, as well as produced it share the texture object, as if the contexts
    were part of the share group. The texture object is deleted once all
    contexts have deleted the texture name associated with the texture object,
    and detached it from all framebuffer objects as well as texture unit
    bindings. See Appendix C of the OpenGL ES 2.0 specification for details
    relative to visibility in one context of changes to the shared texture
    object in another context.

    If glCreateAndConsumeTextureCHROMIUM generates an error, the new texture
    name remains unbound.  It is treated in the same way as a new texture name
    returned by GenTextures.

    INVALID_OPERATION is generated if <mailbox> is not associated with a texture
    object.

New Tokens

    The size of a mailbox name in bytes.

        GL_MAILBOX_SIZE_CHROMIUM                             16

Errors

    None.

New Tokens

    None.

New State

    None.

Revision History

    2011-04-25   Documented the extension
    2013-05-23   Major revision in Produce/Consume semantics, introducing
                 sharing.
    2014-06-02   Added glProduceTextureDirectCHROMIUM and
                 glCreateAndConsumeTextureCHROMIUM definitions.
    2016-08-03   Allow unbinding mailbox using glProduceTextureDirectCHROMIUM.
    2017-10-20   Remove glConsumeTextureCHROMIUM and update
                 glCreateAndConsumeTextureCHROMIUM definition.
    2017-11-20   Remove glProduceTextureCHROMIUM.  Removed <target> arguments
                 from glProduceTextureDirectCHROMIUM and
                 glCreateAndConsumeTextureCHROMIUM, and updated definition.
    2018-06-11   Merge glGenMailboxCHROMIUM into glProduceTextureDirectCHROMIUM.
                 Update documentation to reflect reality.