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GL_NV_blend_square
homeprevnext Name
  
    NV_blend_square  
  
homeprevnext Name Strings
  
    GL_NV_blend_square  
  
homeprevnext Contact
  
    Matt Craighead, NVIDIA Corporation (mcraighead 'at' nvidia.com)  
    Mark J. Kilgard, NVIDIA Corporation (mjk 'at' nvidia.com)  
  
homeprevnext Notice
  
    Copyright NVIDIA Corporation, 1999.  
  
homeprevnext Status
  
    Shipping (version 1.1)  
  
homeprevnext Version
  
    Date: 1/14/2000  Version: 1.1  
    $Date$ $Revision$  
  
homeprevnext Number
  
    194  
  
homeprevnext Dependencies
  
    Written based on the wording of the OpenGL 1.2.1 specification.  
  
homeprevnext Overview
  
    It is useful to be able to multiply a number by itself in the blending  
    stages -- for example, in certain types of specular lighting effects  
    where a result from a dot product needs to be taken to a high power.  
  
    This extension provides four additional blending factors to permit  
    this and other effects: SRC_COLOR and ONE_MINUS_SRC_COLOR for source  
    blending factors, and DST_COLOR and ONE_MINUS_DST_COLOR for destination  
    blending factors.  
  
    Direct3D provides capability bits for advertising these additional  
    blend modes.  
  
homeprevnext Issues
  
    None  
  
homeprevnext New Procedures and Functions
  
    None  
  
homeprevnext New Tokens
  
    None  
  
homeprevnext Additions to Chapter 2 of the OpenGL 1.2.1 Specification (OpenGL Operation)
  
    None  
  
homeprevnext Additions to Chapter 3 of the OpenGL 1.2.1 Specification (Rasterization)
  
    None  
  
homeprevnext Additions to Chapter 4 of the OpenGL 1.2.1 Specification (Per-Fragment Operations and the Framebuffer)
  
    Two lines are added to each of tables 4.1 and 4.2:  
  
        Value                           Blend Factors  
        -----                           -------------  
        ZERO                            (0, 0, 0, 0)  
        ONE                             (1, 1, 1, 1)  
        SRC_COLOR                       (Rs, Gs, Bs, As)                                        NEW  
        ONE_MINUS_SRC_COLOR             (1, 1, 1, 1) - (Rs, Gs, Bs, As)                         NEW  
        DST_COLOR                       (Rd, Gd, Bd, Ad)  
        ONE_MINUS_DST_COLOR             (1, 1, 1, 1) - (Rd, Gd, Bd, Ad)  
        SRC_ALPHA                       (As, As, As, As) / Ka  
        ONE_MINUS_SRC_ALPHA             (1, 1, 1, 1) - (As, As, As, As) / Ka  
        DST_ALPHA                       (Ad, Ad, Ad, Ad) / Ka  
        ONE_MINUS_DST_ALPHA             (1, 1, 1, 1) - (Ad, Ad, Ad, Ad) / Ka  
        CONSTANT_COLOR                  (Rc, Gc, Bc, Ac)  
        ONE_MINUS_CONSTANT_COLOR        (1, 1, 1, 1) - (Rc, Gc, Bc, Ac)  
        CONSTANT_ALPHA                  (Ac, Ac, Ac, Ac)  
        ONE_MINUS_CONSTANT_ALPHA        (1, 1, 1, 1) - (Ac, Ac, Ac, Ac)  
        SRC_ALPHA_SATURATE              (f, f, f, 1)  
  
        Table 4.1: Values controlling the source blending function and the  
        source blending values they compute.  f = min(As, 1 - Ad).  
  
        Value                           Blend Factors  
        -----                           -------------  
        ZERO                            (0, 0, 0, 0)  
        ONE                             (1, 1, 1, 1)  
        SRC_COLOR                       (Rs, Gs, Bs, As)  
        ONE_MINUS_SRC_COLOR             (1, 1, 1, 1) - (Rs, Gs, Bs, As)  
        DST_COLOR                       (Rd, Gd, Bd, Ad)                                        NEW  
        ONE_MINUS_DST_COLOR             (1, 1, 1, 1) - (Rd, Gd, Bd, Ad)                         NEW  
        SRC_ALPHA                       (As, As, As, As) / Ka  
        ONE_MINUS_SRC_ALPHA             (1, 1, 1, 1) - (As, As, As, As) / Ka  
        DST_ALPHA                       (Ad, Ad, Ad, Ad) / Ka  
        ONE_MINUS_DST_ALPHA             (1, 1, 1, 1) - (Ad, Ad, Ad, Ad) / Ka  
        CONSTANT_COLOR_EXT              (Rc, Gc, Bc, Ac)  
        ONE_MINUS_CONSTANT_COLOR_EXT    (1, 1, 1, 1) - (Rc, Gc, Bc, Ac)  
        CONSTANT_ALPHA_EXT              (Ac, Ac, Ac, Ac)  
        ONE_MINUS_CONSTANT_ALPHA_EXT    (1, 1, 1, 1) - (Ac, Ac, Ac, Ac)  
  
        Table 4.2: Values controlling the destination blending function and  
        the destination blending values they compute.  
  
homeprevnext Additions to Chapter 5 of the OpenGL 1.2.1 Specification (Special Functions)
  
    None  
  
homeprevnext Additions to Chapter 6 of the OpenGL 1.2.1 Specification (State and State Requests)
  
    None  
  
homeprevnext Additions to the AGL/GLX/WGL Specifications
  
    None  
  
homeprevnext GLX Protocol
  
    None  
  
homeprevnext Errors
  
    None  
  
homeprevnext New State
  
(table 6.15, page 205)  
    Get Value                 Type  Get Command   Initial Value   Sec    Attribute  
    ------------------------  ----  ------------  -------------   -----  ---------  
    BLEND_SRC                  Z15  GetIntegerv        ONE        4.1.6  color-buffer  
    BLEND_DST                  Z14  GetIntegerv        ZERO       4.1.6  color-buffer  
  
NOTE: the only change is that Z13 changes to Z15 and Z12 changes to Z14  
  
homeprevnext New Implementation Dependent State
  
    None  
  
homeprevnext Revision History
  
    None  
    None  
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