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Fixed alpha composition when destination alpha is transparent. 

Jianyu Guan

I found I make a big mistake that when dstA==0, I just simply let *dstp=*srcp and forgot to make dstRGB = srcRGB*srcA.

The if consition "(*dstp & amask) == 0" in BlitRGBtoRGBPixelAlphaMMX and BlitRGBtoRGBPixelAlphaMMX3dNow should be removed.
Sam Lantinga 2013-08-16 09:20:33 -07:00
parent 89bc80f1ae
commit 76b7b1e96c
1 changed files with 2 additions and 2 deletions
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4
src/video/SDL_blit_A.c
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@ -352,7 +352,7 @@ BlitRGBtoRGBPixelAlphaMMX(SDL_BlitInfo * info)
Uint32 alpha = *srcp & amask;
if (alpha == 0) {
/* do nothing */
} else if (alpha == amask || (*dstp & amask) == 0) {
} else if (alpha == amask) {
*dstp = *srcp;
} else {
src1 = _mm_cvtsi32_si64(*srcp); /* src(ARGB) -> src1 (0000ARGB)*/
@ -545,7 +545,7 @@ BlitRGBtoRGBPixelAlphaMMX3DNOW(SDL_BlitInfo * info)
alpha = *srcp & amask;
if (alpha == 0) {
/* do nothing */
} else if (alpha == amask || (*dstp & amask) == 0) {
} else if (alpha == amask) {
*dstp = *srcp;
} else {
src1 = _mm_cvtsi32_si64(*srcp); /* src(ARGB) -> src1 (0000ARGB)*/