pandory500/SDL-mirror
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Updated blend semantics so blending uses the following formula:

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dstRGB = (srcRGB * srcA) + (dstRGB * (1-srcA))
    dstA = srcA + (dstA * (1-srcA))
This allows proper compositing semantics without requiring premultiplied alpha.

Needs full unit test coverage and bug fixes!
This commit is contained in:
Sam Lantinga 2013-07-23 08:06:49 -07:00
parent a99edf3519
commit 32188834b5
17 changed files with 362 additions and 1001 deletions
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6
src/render/opengles2/SDL_render_gles2.c
View file

@ -994,15 +994,15 @@ GLES2_SetBlendMode(GLES2_DriverContext *rdata, int blendMode)
break;
case SDL_BLENDMODE_BLEND:
rdata->glEnable(GL_BLEND);
rdata->glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
rdata->glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
break;
case SDL_BLENDMODE_ADD:
rdata->glEnable(GL_BLEND);
rdata->glBlendFunc(GL_SRC_ALPHA, GL_ONE);
rdata->glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE, GL_ZERO, GL_ONE);
break;
case SDL_BLENDMODE_MOD:
rdata->glEnable(GL_BLEND);
rdata->glBlendFunc(GL_ZERO, GL_SRC_COLOR);
rdata->glBlendFuncSeparate(GL_ZERO, GL_SRC_COLOR, GL_ZERO, GL_ONE);
break;
}
rdata->current.blendMode = blendMode;