extensions/EXT/GLX_EXT_get_drawable_type.txt

Name

    EXT_get_drawable_type

Name Strings

    GLX_EXT_get_drawable_type

Contributors

    Adam Jackson, Red Hat
    Kyle Brenneman, NVIDIA

Contacts

    Adam Jackson <ajax@redhat.com>

Status

    Complete.

Version

    Version 3, 24 September 2020

Number

    OpenGL Extension #552

Dependencies

    GLX 1.3 or higher is required.

    This extension is written against the text of the GLX 1.4 specification.

Overview

    This extension adds to the set of drawable attributes that are sent in
    a GLXGetDrawableAttributes request, and that can be queried with
    glXQueryDrawable. While this is primarily a convenience for the client
    library implementation, it may also be useful for applications.

New Types

    None

New Procedures and Functions

    None

New Tokens

    New attributes accepted for the <attribute> argument of
    glXQueryDrawable:

        GLX_DRAWABLE_TYPE                       0x8010

Additions to the GLX 1.4 specification

    In Section 3.3.6 "Querying Attributes", add GLX_DRAWABLE_TYPE to the
    list of legal values for the <attribute> parameter. The returned value
    must have exactly one of GLX_{WINDOW,PIXMAP,PBUFFER}_BIT set.

Issues

    1) Why add GLX_DRAWABLE_TYPE?

    An X client may get the XID of a GLXDrawable from another process. When
    this happens, the client library needs to import the drawable's state as
    if the client had created it itself. Since different drawable types may
    require different handling, this attribute allows the client library to
    distinguish between windows, pixmaps, and pbuffers.

    2) Why use GLX_*_BIT for the GLX_DRAWABLE_TYPE value?

    GLX_WINDOW and GLX_PBUFFER exist, but GLX_PIXMAP does not.

    3) Are there other attributes we should add?

    RESOLVED. No, there aren't any other drawable (not fbconfig) attributes in
    core GLX that aren't currently exposed, as far as we can tell. Drawable
    attributes added by GLX extensions can be added in separate extensions.

Revision History

    Version 3, 24 September 2020
    - Resolve issues, assign extension number, and mark as complete.

    Version 2, 9 September 2020
    - Change name to GLX_EXT_get_drawable_type.

    Version 1, 24 August 2020
    - Initial draft.