Name

    ARB_texture_env_dot3

Name Strings

    GL_ARB_texture_env_dot3
    
Contact

    Bimal Poddar, Intel, bimal.poddar@intel.com
    Dave Gosselin, ATI Technologies, Inc. (gosselin 'at' ati.com)
    Dan Ginsburg, ATI Technologies, Inc. (dginsbur 'at' ati.com)

Status

    Complete. Approved by ARB on February 16, 2001.

Version

    Last modified date: 2001/02/02

Number

    ARB Extension #19

Dependencies

    This extension is written against the OpenGL 1.2.1 Specification.
    OpenGL 1.1, ARB_multitexture and ARB_texture_env_combine are required 
    for this extension.

Overview

    Adds new operation to the texture combiner operations.

        DOT3_RGB_ARB                    Arg0 <dotprod> Arg1
        DOT3_RGBA_ARB                   Arg0 <dotprod> Arg1

    where Arg0, Arg1 are specified by <params> parameter of 
    TexEnvf, TexEnvi, TexEnvfv, and TexEnviv when the <pname>
    parameter value is SOURCE0_RGB_ARB and SOURCE1_RGB_ARB.
    
Issues

 1. This extension is an ARB version of EXT_texture_env_dot3 which bears
    a copyright by ATI Technologies. Is ATI willing to have the ARB
    go ahead and modify their original spec and use it for the 
    ARB extension.

    - RESOLVED: ATI does not have a problem with the copyright issue.

 2. The EXT version of the spec does not multiply the output by 
    RGB_SCALE_ARB and ALPHA_SCALE_ARB. There is no reason to impose this
    restriction since it makes the scale operations non-orthogonal. 
    Should the enum values for the new tokens in this extension should
    be the same as the original EXT version?

    - RESOLVED: No.

New Procedures and Functions

    None

New Tokens

    Accepted by the <params> parameter of TexEnvf, TexEnvi, TexEnvfv,
    and TexEnviv when the <pname> parameter value is COMBINE_RGB_ARB
    or COMBINE_ALPHA_ARB

        DOT3_RGB_ARB                                    0x86AE
        DOT3_RGBA_ARB                                   0x86AF

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

    None

Additions to Chapter 3 of the GL Specification (Rasterization)

    Added to table 3.20 of the ARB_texture_env_combine spec:

        COMBINE_RGB_ARB         Texture Function
        ---------------         ----------------
        DOT3_RGB_ARB            4*((Arg0_r - 0.5)*(Arg1_r - 0.5) +
                                   (Arg0_g - 0.5)*(Arg1_g - 0.5) +
                                   (Arg0_b - 0.5)*(Arg1_b - 0.5))

                                This value is placed into all three
                                r,g,b components of the output.

        DOT3_RGBA_ARB           4*((Arg0_r - 0.5)*(Arg1_r - 0.5) +
                                   (Arg0_g - 0.5)*(Arg1_g - 0.5) +
                                   (Arg0_b - 0.5)*(Arg1_b - 0.5))

                                This value is placed into all four
                                r,g,b,a components of the output. Note
                                that the result generated from 
                                COMBINE_ALPHA_ARB function is ignored.

Additions to Chapter 4 of the OpenGL 1.2 Specification (Per-Fragment Operations
and the Framebuffer)

    None

Additions to Chapter 5 of the GL Specification (Special Functions)

    None

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

    None

Additions to the GLX Specification

    None

GLX Protocol

    None

Errors

    INVALID_ENUM is generated if <params> value for COMBINE_RGB_ARB
    is not one of REPLACE, MODULATE, ADD, ADD_SIGNED_ARB, 
    INTERPOLATE_ARB, SUBTRACT_ARB, DOT3_RGB_ARB or DOT3_RGBA_ARB.

New State

    None

New Implementation Dependent State

    None

Revision History
    01/02/02  bpoddar   Added original EXT/ARB contributors to the contact
                        list

    00/12/13  bpoddar   Added enum values for DOT3_RGB_ARB and DOT3_RGBA_ARB
                        Added resolution to issue # 1.

    00/12/06  bpoddar   Fixed typos - EXT -> ARB, RED_SCALE -> RGB_SCALE

    00/12/01  bpoddar   Created an ARB version of the ARB_texture_env_dot3 
                        by breaking up the proposed ARB_texture_env_combine
                        spec.