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Fixed bug 3159 - SDL_blit_slow with BLENDING does not work 

Fritzor

Source Suface is ABGR and Destination Surface is ABGR. We use software blending. In the Switch-Case statement for SDL_COPY_BLEND (Line 126) the alpha-channel is not calculated like in every SDL_blit_auto - function. So if the destination Surface has alpha - channel of zero the resulting surface has zero as well.
Add:  ?dstA = srcA + ((255 - srcA) * dstA) / 255;? to code and everything is okay.
This commit is contained in:
Sam Lantinga 2016-10-01 13:40:01 -07:00
parent 13dd2ccda8
commit 473051f6bb
1 changed files with 1 additions and 0 deletions
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src/video/SDL_blit_slow.c
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@ -129,6 +129,7 @@ SDL_Blit_Slow(SDL_BlitInfo * info)
dstR = srcR + ((255 - srcA) * dstR) / 255; dstR = srcR + ((255 - srcA) * dstR) / 255;
dstG = srcG + ((255 - srcA) * dstG) / 255; dstG = srcG + ((255 - srcA) * dstG) / 255;
dstB = srcB + ((255 - srcA) * dstB) / 255; dstB = srcB + ((255 - srcA) * dstB) / 255;
dstA = srcA + ((255 - srcA) * dstA) / 255;
break; break;
case SDL_COPY_ADD: case SDL_COPY_ADD:
dstR = srcR + dstR; dstR = srcR + dstR;