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Weight RGB values by alpha

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Alexander van Gessel 2017-11-05 18:02:47 +01:00 • committed by Charles Dang
parent 8f730f2dd3
commit e226ef324a
1 changed files with 13 additions and 7 deletions
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20
src/sdl/utils.cpp
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@ -1622,22 +1622,28 @@ surface blur_alpha_surface(const surface &surf, int depth)
Average() : alpha(), red(), green(), blue()
{}
Average& operator+=(const Pixel& pix){
red += pix.red;
green += pix.green;
blue += pix.blue;
red += pix.alpha * pix.red;
green += pix.alpha * pix.green;
blue += pix.alpha * pix.blue;
alpha += pix.alpha;
return *this;
}
Average& operator-=(const Pixel& pix){
red -= pix.red;
green -= pix.green;
blue -= pix.blue;
red -= pix.alpha * pix.red;
green -= pix.alpha * pix.green;
blue -= pix.alpha * pix.blue;
alpha -= pix.alpha;
return *this;
}
Uint32 operator()(unsigned num){
const Uint32 ff = 0xff;
return (std::min(alpha/num,ff) << 24) | (std::min(red/num,ff) << 16) | (std::min(green/num,ff) << 8) | std::min(blue/num,ff);
if(!alpha){
return 0;
}
return (std::min(alpha/num,ff) << 24)
| (std::min(red/alpha,ff) << 16)
| (std::min(green/alpha,ff) << 8)
| std::min(blue/alpha,ff);
}
};