xref: /third_party/EGL/extensions/EXT/EGL_EXT_config_select_group.txt

Name

    EGL_EXT_config_select_group

Name Strings

    EGL_EXT_config_select_group

Contributors

    Hal Gentz <zegentzy@protonmail.com>
    Adam Jackson <ajax@redhat.com>
    Robert Mader <robert.mader@posteo.de>

Contacts

    Hal Gentz <zegentzy@protonmail.com>

Status

    Draft

Version

    Version 4, 2021-06-24

Number

    EGL Extension #145

Extension Type

    EGL client extension

Dependencies

    This extension is written against the wording of the 2014.08.27 revision
    of the EGL 1.5 Specification.

Overview

    This extension provides a mechanism to lower the config selection priority
    of the configs returned by eglChooseConfig. A new config attribute is
    introduced, providing a way for the implementation to group configs into
    different config selection categories.  The config selection priorities of
    all the configs in one category may be higher or lower than the ones in
    other categories.  The config selection priorities in one category follow
    the rules of eglChooseConfig. See also GLX_SGIX_visual_select_group.

New Types

    None

New Procedures and Functions

    None

New Tokens

    Accepted as a new EGLConfig attribute:

        EGL_CONFIG_SELECT_GROUP_EXT                0x34C0

Additions to the EGL 1.5 Specification

    In section 3.4 "Configuration Management", under the "Buffer Descriptions
    and Attributes" heading, append to table 3.1 the following:

    "EGL_CONFIG_SELECT_GROUP_EXT | integer | the config select group"

    In section 3.4 "Configuration Management", under the "Other EGLConfig
    Attribute Descriptions" heading, append to the end the following:

    "The attribute EGL_CONFIG_SELECT_GROUP_EXT is used to specify the config
    selection category of the config. Configs in the i-th category have a higher
    config selection priority than those found in the (i+1)-th category.

    "The attribute EGL_CONFIG_SELECT_GROUP_EXT is used by the implementation to
    override the default sorting rules, by collecting configurations into
    groups. It is not accepted by the <attrib_list> parameter of
    eglChooseConfig, but it is accepted as the <attribute> in
    eglGetConfigAtrrib."

    In section 3.4 "Configuration Management", under the "Sorting of EGLConfigs"
    heading, append to table 3.4 the following:

    "EGL_CONFIG_SELECT_GROUP_EXT | 0 | Ignore | Smaller | 0"

    In section 3.4 "Configuration Management", under the "Sorting of EGLConfigs"
    heading, append before the list entry which starts with "1. Special: by
    EGL_CONFIG_CAVEAT" the following entry:

    "0. Smaller EGL_CONFIG_SELECT_GROUP_EXT."

Issues

    None

Revision History

    Version 4, 2021-06-24 (Robert Mader)
        - Moved to EXT, changed enum value to 0x34C0.

    Version 3, 2020-04-06 (Robert Mader)
        - Changed enum value to 0x31DF, added contributors.

    Version 2, 2019-07-11 (Hal Gentz)
        - Resolved issues pointed out by Adam Jackson.

    Version 1, 2019-06-21 (Hal Gentz)
        - Initial draft