eden-emu/SDL
20
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Fixed bug 4903 - Lack of color multiply with alpha (SDL_BLENDMODE_MOD + SDL_BLENDMODE_BLEND) blending mode for all renderers

Browse source 
Konrad

This kind of blending is rather quite useful and in my opinion should be available for all renderers. I do need it myself, but since I didn't want to use a custom blending mode which is supported only by certain renderers (e.g. not in software which is quite important for me) I did write implementation of SDL_BLENDMODE_MUL for all renderers altogether.

SDL_BLENDMODE_MUL implements following equation:

dstRGB = (srcRGB * dstRGB) + (dstRGB * (1-srcA))
dstA = (srcA * dstA) + (dstA * (1-srcA))

Background:

https://i.imgur.com/UsYhydP.png

Blended texture:

https://i.imgur.com/0juXQcV.png

Result for SDL_BLENDMODE_MOD:

https://i.imgur.com/wgNSgUl.png

Result for SDL_BLENDMODE_MUL:

https://i.imgur.com/Veokzim.png

I think I did cover all possibilities within included patch, but I didn't write any tests for SDL_BLENDMODE_MUL, so it would be lovely if someone could do it.
This commit is contained in:
Sam Lantinga 2020-01-16 08:52:59 -08:00
parent 669729a8a0
commit 981e0d367c
19 changed files with 819 additions and 159 deletions
Download patch file Download diff file Expand all files Collapse all files

7
src/render/psp/SDL_render_psp.c
View file

@ -676,7 +676,12 @@ PSP_SetBlendMode(SDL_Renderer * renderer, int blendMode)
case SDL_BLENDMODE_MOD:
sceGuTexFunc(GU_TFX_MODULATE , GU_TCC_RGBA);
sceGuEnable(GU_BLEND);
sceGuBlendFunc( GU_ADD, GU_FIX, GU_SRC_COLOR, 0, 0);
sceGuBlendFunc(GU_ADD, GU_FIX, GU_SRC_COLOR, 0, 0);
break;
case SDL_BLENDMODE_MUL:
sceGuTexFunc(GU_TFX_MODULATE , GU_TCC_RGBA);
sceGuEnable(GU_BLEND);
sceGuBlendFunc(GU_ADD, GU_DST_COLOR, GU_ONE_MINUS_SRC_ALPHA, 0, 0);
break;
}
data->currentBlendMode = blendMode;