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Text File  |  2001-04-17  |  13.7 KB  |  199 lines
  1.  
  2.  
  3.  
  4. ggggllllBBBBlllleeeennnnddddEEEEqqqquuuuaaaattttiiiioooonnnnEEEEXXXXTTTT((((3333GGGG))))         OOOOppppeeeennnnGGGGLLLL RRRReeeeffffeeeerrrreeeennnncccceeee         ggggllllBBBBlllleeeennnnddddEEEEqqqquuuuaaaattttiiiioooonnnnEEEEXXXXTTTT((((3333GGGG))))
  5.  
  6.  
  7.  
  8. NNNNAAAAMMMMEEEE
  9.      ggggllllBBBBlllleeeennnnddddEEEEqqqquuuuaaaattttiiiioooonnnnEEEEXXXXTTTT - set the blend equation
  10.  
  11.  
  12. CCCC SSSSPPPPEEEECCCCIIIIFFFFIIIICCCCAAAATTTTIIIIOOOONNNN
  13.      void ggggllllBBBBlllleeeennnnddddEEEEqqqquuuuaaaattttiiiioooonnnnEEEEXXXXTTTT( GLenum _m_o_d_e )
  14.  
  15.  
  16. PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRRSSSS
  17.      _m_o_d_e  specifies how source and destination colors are combined.  It must
  18.            be GGGGLLLL____FFFFUUUUNNNNCCCC____AAAADDDDDDDD____EEEEXXXXTTTT, GGGGLLLL____FFFFUUUUNNNNCCCC____SSSSUUUUBBBBTTTTRRRRAAAACCCCTTTT____EEEEXXXXTTTT,
  19.            GGGGLLLL____FFFFUUUUNNNNCCCC____RRRREEEEVVVVEEEERRRRSSSSEEEE____SSSSUUUUBBBBTTTTRRRRAAAACCCCTTTT____EEEEXXXXTTTT, GGGGLLLL____MMMMIIIINNNN____EEEEXXXXTTTT, GGGGLLLL____MMMMAAAAXXXX____EEEEXXXXTTTT,
  20.            GGGGLLLL____AAAALLLLPPPPHHHHAAAA____MMMMIIIINNNN____SSSSGGGGIIIIXXXX, GGGGLLLL____AAAALLLLPPPPHHHHAAAA____MMMMAAAAXXXX____SSSSGGGGIIIIXXXX, or GGGGLLLL____LLLLOOOOGGGGIIIICCCC____OOOOPPPP.
  21.  
  22.  
  23. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  24.      The blend equation determines how a new pixel (the ``source'' color) is
  25.      combined with a pixel already in the framebuffer (the ``destination''
  26.      color).
  27.  
  28.      GGGGLLLL____MMMMIIIINNNN____EEEEXXXXTTTT
  29.           sets the blend equation so that each component of the result color
  30.           is the minimum of the corresponding components of the source and
  31.           destination colors.
  32.  
  33.      GGGGLLLL____MMMMAAAAXXXX____EEEEXXXXTTTT
  34.           sets the blend equation so that each component of the result color
  35.           is the maximum of the corresponding components of the source and
  36.           destination colors.
  37.  
  38.      GGGGLLLL____AAAALLLLPPPPHHHHAAAA____MMMMIIIINNNN____SSSSGGGGIIIIXXXX
  39.           sets the blend equation so that the result color is either the
  40.           source or destination color, according to whether the alpha
  41.           component of the source color is less than, or greater than or equal
  42.           to, the alpha component of the destination color, respectively.
  43.  
  44.      GGGGLLLL____AAAALLLLPPPPHHHHAAAA____MMMMAAAAXXXX____SSSSGGGGIIIIXXXX
  45.           sets the blend equation so that the result color is either the
  46.           source or destination color, according to whether the alpha
  47.           component of the source color is greater than, or less than or equal
  48.           to, the alpha component of the destination color, respectively.
  49.  
  50.      GGGGLLLL____LLLLOOOOGGGGIIIICCCC____OOOOPPPP
  51.           sets the blend equation so that each component of the result color
  52.           is a bitwise logical combination of the corresponding components of
  53.           the source and destination colors.  Use the ggggllllLLLLooooggggiiiiccccOOOOpppp command to
  54.           specify the logical operator.
  55.  
  56.      The remaining blend equations use the source and destination blend
  57.      factors specified by ggggllllBBBBlllleeeennnnddddFFFFuuuunnnncccc.  See ggggllllBBBBlllleeeennnnddddFFFFuuuunnnncccc for a description of
  58.      the various blend factors.
  59.  
  60.  
  61.  
  62.  
  63.                                                                         PPPPaaaaggggeeee 1111
  64.  
  65.  
  66.  
  67.  
  68.  
  69.  
  70. ggggllllBBBBlllleeeennnnddddEEEEqqqquuuuaaaattttiiiioooonnnnEEEEXXXXTTTT((((3333GGGG))))         OOOOppppeeeennnnGGGGLLLL RRRReeeeffffeeeerrrreeeennnncccceeee         ggggllllBBBBlllleeeennnnddddEEEEqqqquuuuaaaattttiiiioooonnnnEEEEXXXXTTTT((((3333GGGG))))
  71.  
  72.  
  73.  
  74.      In the equations that follow, source and destination color components are
  75.      referred to as (Rs,Gs,Bs,As) and (Rd,Gd,Bd,Ad), respectively.  The result
  76.      color is referred to as (Rr,Gr,Br,Ar).  The source and destination blend
  77.      factors are denoted (sR,sG,sB,sA) and (dR,dG,dB,dA), respectively.  For
  78.      these equations all color components are understood to have values
  79.      between 0.0 and 1.0, inclusive.
  80.  
  81.      GGGGLLLL____FFFFUUUUNNNNCCCC____AAAADDDDDDDD____EEEEXXXXTTTT
  82.           sets the blend equation so that the source and destination data are
  83.           added.  Each component of the source color is multiplied by the
  84.           corresponding source factor, then each component of the destination
  85.           color is multiplied by the corresponding destination factor.  The
  86.           result is the componentwise sum of the two products, clamped to the
  87.           range [0,1].
  88.  
  89.                              Rr = min(1,  Rs sR  +  Rd dR)
  90.                              Gr = min(1,  Gs sG  +  Gd dG)
  91.                              Br = min(1,  Bs sB  +  Bd dB)
  92.                              Ar = min(1,  As sA  +  Ad dA)
  93.  
  94.      GGGGLLLL____FFFFUUUUNNNNCCCC____SSSSUUUUBBBBTTTTRRRRAAAACCCCTTTT____EEEEXXXXTTTT
  95.           Is like GGGGLLLL____FFFFUUUUNNNNCCCC____AAAADDDDDDDD____EEEEXXXXTTTT except the product of the destination factor
  96.           and the destination color is componentwise subtracted from the
  97.           product of the source factor and the source color.  The result is
  98.           clamped to the range [0,1].
  99.                              Rr = max(0,  Rs sR  -  Rd dR)
  100.                              Gr = max(0,  Gs sG  -  Gd dG)
  101.                              Br = max(0,  Bs sB  -  Bd dB)
  102.                              Ar = max(0,  As sA  -  Ad dA)
  103.  
  104.      GGGGLLLL____FFFFUUUUNNNNCCCC____RRRREEEEVVVVEEEERRRRSSSSEEEE____SSSSUUUUBBBBTTTTRRRRAAAACCCCTTTT____EEEEXXXXTTTT
  105.           Is like GGGGLLLL____FFFFUUUUNNNNCCCC____AAAADDDDDDDD____EEEEXXXXTTTT except the product of the source factor and
  106.           the source color is componentwise subtracted from the product of the
  107.           destination factor and the destination color.  The result is clamped
  108.           to the range [0,1].
  109.                              Rr = max(0,  Rd dR  -  Rs sR)
  110.                              Gr = max(0,  Gd dG  -  Gs sG)
  111.                              Br = max(0,  Bd dB  -  Bs sB)
  112.                              Ar = max(0,  Ad dA  -  As sA)
  113.  
  114.  
  115.      The GGGGLLLL____MMMMIIIINNNN____EEEEXXXXTTTT and GGGGLLLL____MMMMAAAAXXXX____EEEEXXXXTTTT equations are useful for applications that
  116.      analyze image data (image thresholding against a constant color, for
  117.      example).  The GGGGLLLL____LLLLOOOOGGGGIIIICCCC____OOOOPPPP equation is most commonly used with GGGGLLLL____XXXXOOOORRRR for
  118.      reversible drawing.  The GGGGLLLL____FFFFUUUUNNNNCCCC____AAAADDDDDDDD____EEEEXXXXTTTT equation is useful for anti-
  119.      aliasing and transparency, among other things.
  120.  
  121.      Initially the blend equation is set to GGGGLLLL____FFFFUUUUNNNNCCCC____AAAADDDDDDDD____EEEEXXXXTTTT.
  122.  
  123.  
  124.  
  125.  
  126.  
  127.  
  128.  
  129.                                                                         PPPPaaaaggggeeee 2222
  130.  
  131.  
  132.  
  133.  
  134.  
  135.  
  136. ggggllllBBBBlllleeeennnnddddEEEEqqqquuuuaaaattttiiiioooonnnnEEEEXXXXTTTT((((3333GGGG))))         OOOOppppeeeennnnGGGGLLLL RRRReeeeffffeeeerrrreeeennnncccceeee         ggggllllBBBBlllleeeennnnddddEEEEqqqquuuuaaaattttiiiioooonnnnEEEEXXXXTTTT((((3333GGGG))))
  137.  
  138.  
  139.  
  140. NOTES
  141.      The GGGGLLLL____MMMMIIIINNNN____EEEEXXXXTTTT, GGGGLLLL____MMMMAAAAXXXX____EEEEXXXXTTTT, GGGGLLLL____AAAALLLLPPPPHHHHAAAA____MMMMIIIINNNN____SSSSGGGGIIIIXXXX, GGGGLLLL____AAAALLLLPPPPHHHHAAAA____MMMMAAAAXXXX____SSSSGGGGIIIIXXXX and
  142.      GGGGLLLL____LLLLOOOOGGGGIIIICCCC____OOOOPPPP equations do not use the source or destination factors, only
  143.      the source and destination colors.
  144.  
  145. EEEERRRRRRRROOOORRRRSSSS
  146.      GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____EEEENNNNUUUUMMMM is generated if _m_o_d_e is not one of GGGGLLLL____FFFFUUUUNNNNCCCC____AAAADDDDDDDD____EEEEXXXXTTTT,
  147.      GGGGLLLL____FFFFUUUUNNNNCCCC____SSSSUUUUBBBBTTTTRRRRAAAACCCCTTTT____EEEEXXXXTTTT, GGGGLLLL____FFFFUUUUNNNNCCCC____RRRREEEEVVVVEEEERRRRSSSSEEEE____SSSSUUUUBBBBTTTTRRRRAAAACCCCTTTT____EEEEXXXXTTTT, GGGGLLLL____MMMMAAAAXXXX____EEEEXXXXTTTT,
  148.      GGGGLLLL____MMMMIIIINNNN____EEEEXXXXTTTT, or GGGGLLLL____LLLLOOOOGGGGIIIICCCC____OOOOPPPP.
  149.  
  150.      GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____OOOOPPPPEEEERRRRAAAATTTTIIIIOOOONNNN is generated if ggggllllBBBBlllleeeennnnddddEEEEqqqquuuuaaaattttiiiioooonnnnEEEEXXXXTTTT is executed
  151.      between the execution of ggggllllBBBBeeeeggggiiiinnnn and the corresponding execution of
  152.      ggggllllEEEEnnnndddd.
  153.  
  154. AAAASSSSSSSSOOOOCCCCIIIIAAAATTTTEEEEDDDD GGGGEEEETTTTSSSS
  155.      ggggllllGGGGeeeetttt with an argument of GGGGLLLL____BBBBLLLLEEEENNNNDDDD____EEEEQQQQUUUUAAAATTTTIIIIOOOONNNN____EEEEXXXXTTTT.
  156.  
  157.      ggggllllGGGGeeeettttSSSSttttrrrriiiinnnngggg with an argument of GGGGLLLL____EEEEXXXXTTTTEEEENNNNSSSSIIIIOOOONNNNSSSS.
  158.           This feature is not part of standard GL. The extensions string of
  159.           ggggllllGGGGeeeettttSSSSttttrrrriiiinnnngggg will contain the name bbbblllleeeennnndddd____mmmmiiiinnnnmmmmaaaaxxxx if GGGGLLLL____MMMMIIIINNNN____EEEEXXXXTTTT and
  160.           GGGGLLLL____MMMMAAAAXXXX____EEEEXXXXTTTT are supported.  It will contain the name bbbblllleeeennnndddd____llllooooggggiiiicccc____oooopppp
  161.           if GGGGLLLL____LLLLOOOOGGGGIIIICCCC____OOOOPPPP is supported in RGB mode. It will contain the name
  162.           bbbblllleeeennnndddd____ssssuuuubbbbttttrrrraaaacccctttt if GGGGLLLL____FFFFUUUUNNNNCCCC____SSSSUUUUBBBBTTTTRRRRAAAACCCCTTTT____EEEEXXXXTTTT and
  163.           GGGGLLLL____FFFFUUUUNNNNCCCC____RRRREEEEVVVVEEEERRRRSSSSEEEE____SSSSUUUUBBBBTTTTRRRRAAAACCCCTTTT____EEEEXXXXTTTT are supported.
  164.  
  165.  
  166. MMMMAAAACCCCHHHHIIIINNNNEEEE DDDDEEEEPPPPEEEENNNNDDDDEEEENNNNCCCCIIIIEEEESSSS
  167.      RRRReeeeaaaalllliiiittttyyyyEEEEnnnnggggiiiinnnneeee, RRRReeeeaaaalllliiiittttyyyyEEEEnnnnggggiiiinnnneeee2222, and VVVVTTTTXXXX systems do not support the use of
  168.      blend factor GGGGLLLL____SSSSRRRRCCCC____AAAALLLLPPPPHHHHAAAA____SSSSAAAATTTTUUUURRRRAAAATTTTEEEE with blend equation
  169.      GGGGLLLL____FFFFUUUUNNNNCCCC____RRRREEEEVVVVEEEERRRRSSSSEEEE____SSSSUUUUBBBBTTTTRRRRAAAACCCCTTTT____EEEEXXXXTTTT; this combination produces incorrect
  170.      results.
  171.  
  172.      The SGIX_blend_alpha_minmax extension is supported only on OOOOccccttttaaaannnneeee2222 VVVVPPPPrrrroooo
  173.      systems.
  174.  
  175.  
  176. SSSSEEEEEEEE AAAALLLLSSSSOOOO
  177.      ggggllllGGGGeeeettttSSSSttttrrrriiiinnnngggg, ggggllllBBBBlllleeeennnnddddCCCCoooolllloooorrrrEEEEXXXXTTTT, ggggllllBBBBlllleeeennnnddddFFFFuuuunnnncccc.
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  195.                                                                         PPPPaaaaggggeeee 3333
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  199.