Merged r4992:4993 from branches/SDL-1.2: increased alpha blend accuracy.
--- a/src/video/SDL_blit.h Sun Jan 10 05:39:46 2010 +0000
+++ b/src/video/SDL_blit.h Sun Jan 10 06:18:39 2010 +0000
@@ -444,9 +444,9 @@
/* Blend the RGB values of two Pixels based on a source alpha value */
#define ALPHA_BLEND(sR, sG, sB, A, dR, dG, dB) \
do { \
- dR = ((((int)(sR-dR)*(int)A)/255)+dR); \
- dG = ((((int)(sG-dG)*(int)A)/255)+dG); \
- dB = ((((int)(sB-dB)*(int)A)/255)+dB); \
+ dR = (((((int)(sR-dR)*((int)A))+255)/255)+dR); \
+ dG = (((((int)(sG-dG)*((int)A))+255)/255)+dG); \
+ dB = (((((int)(sB-dB)*((int)A))+255)/255)+dB); \
} while(0)