xref: /third_party/openGLES/extensions/S3/S3_s3tc.txt

XXX - Not complete yet!!!

Name

    S3_s3tc

Name Strings

    GL_S3_s3tc

Contact

    Unknown.

IP Status

    There is significant IP associated with the S3TC format. In 1999 S3
    told the OpenGL ARB that they would not license it for general use
    in OpenGL. IHVs shipping this extension probably have executed
    licenses directly with S3 or its successors (Sonic Blue, S3
    Graphics).

    The current ownership of the S3TC IP is unknown to the ARB. It is
    known that when S3 exited the graphics hardware business, part of
    their operations were sold to ATI and part were spun off to a joint
    Taiwanese venture with Via Technologies, called S3 Graphics.

Status

    Shipping in several vendor drivers.
    Deprecated in favor of EXT_texture_compression_s3tc.

Version

    Unknown

Number

    276

Dependencies

    OpenGL 1.1 is required.
    The extension is not specified; only the new tokens are known.

Overview

    This extension allows specifying texture data in compressed S3TC
    format.

Issues

  * Need a specification, at least at a functional level. No
    detailed online documentation can be found in Google, only
    enum values.

New Procedures and Functions

    None.

New Tokens

    Accepted by the ??? parameter of ??? (presumably by the <format>
    argument of TexImage2D?):

        RGB_S3TC                            0x83A0
        RGB4_S3TC                           0x83A1
        RGBA_S3TC                           0x83A2
        RGBA4_S3TC                          0x83A3
        RGBA_DXT5_S3TC                      0x83A4
        RGBA4_DXT5_S3TC                     0x83A5

Additions to Chapter 2 of the OpenGL 1.2 Specification (OpenGL Operation)

    Unknown.

Additions to Chapter 3 of the OpenGL 1.2.1 Specification (Rasterization)

    Unknown. Probably only changes to accepted client texture formats
    for 2D textures.

Additions to Chapter 4 of the OpenGL 1.2.1 Specification (Per-Fragment
Operations and the Frame Buffer)

    Unknown.

Additions to Chapter 5 of the OpenGL 1.2.1 Specification (Special Functions)

    Unknown.

Additions to Chapter 6 of the OpenGL 1.2 Specification (State and State
Requests)

    Unknown.

Additions to Appendix A of the OpenGL 1.2.1 Specification (Invariance)

    Unknown.

Additions to the GLX / WGL / AGL Specifications

    None

GLX Protocol

    Unknown. Passing compressed data would affect the computed data
    size, so some enhancements to the existing TexImage2D protocol might
    be needed.

Errors

    Unknown.

New State

    Unknown.

Revision History

  * Revision 2, January 17, 2003 (Mark Kilgard) - Document
    RGBA_DXT5_S3TC and RGBA4_DXT5_S3TC enumerants. Update status as
    deprecated in favor of EXT_texture_compression_s3tc spec.

  * Revision 1, December 18, 2002 (Jon Leech) - Minimal documentation on
    the extension based on public header files.