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26 lines
428 B
Plaintext
26 lines
428 B
Plaintext
/*
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* simulate scanlines by darkening every other line.
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*
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*/
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kernel vec4 scanline(sampler image, float strength)
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{
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vec4 fudge = vec4( 0.4, 0.4, 0.4, 0.0 );
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vec2 coord = samplerCoord(image);
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vec4 pixel = sample(image, coord);
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fudge *= strength;
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float yy = mod(coord.y, 2.0);
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fudge *= (yy < 1.0) ? 1.0 : -1.0;
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pixel = unpremultiply(pixel);
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pixel += fudge;
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return premultiply(pixel);
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}
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