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comparison src/video/SDL_blit.h @ 3437:dc2911c207e4

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Thank you automated tests (and bobbens!), fixed alpha blending for accuracy
author Sam Lantinga <slouken@libsdl.org>
date Mon, 16 Nov 2009 09:47:34 +0000
parents 90aec03bf9fd
children 83910f4c373f
comparison
equal deleted inserted replaced
3436:0538362b98d3 3437:dc2911c207e4
442 } 442 }
443 443
444 /* Blend the RGB values of two Pixels based on a source alpha value */ 444 /* Blend the RGB values of two Pixels based on a source alpha value */
445 #define ALPHA_BLEND(sR, sG, sB, A, dR, dG, dB) \ 445 #define ALPHA_BLEND(sR, sG, sB, A, dR, dG, dB) \
446 do { \ 446 do { \
447 dR = (((sR-dR)*(A)+255)>>8)+dR; \ 447 dR = ((((int)(sR-dR)*(int)A)/255)+dR); \
448 dG = (((sG-dG)*(A)+255)>>8)+dG; \ 448 dG = ((((int)(sG-dG)*(int)A)/255)+dG); \
449 dB = (((sB-dB)*(A)+255)>>8)+dB; \ 449 dB = ((((int)(sB-dB)*(int)A)/255)+dB); \
450 } while(0) 450 } while(0)
451 451
452 452
453 /* This is a very useful loop for optimizing blitters */ 453 /* This is a very useful loop for optimizing blitters */
454 #if defined(_MSC_VER) && (_MSC_VER == 1300) 454 #if defined(_MSC_VER) && (_MSC_VER == 1300)