48 lines
1.3 KiB
GLSL
48 lines
1.3 KiB
GLSL
// https://en.wikipedia.org/wiki/Ordered_dithering
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#define BAYER 4
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#if BAYER == 2
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const float threshold[4] = float[4](
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1/4.,2/4.,
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3/4.,1/4.
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);
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#elif BAYER == 4
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const float threshold[16] = float[16](
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1/16., 9/16., 3/16., 11/16.,
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13/16., 5/16., 15/16., 7/16.,
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4/16., 12/16., 2/16., 10/16.,
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16/16., 8/16., 14/16., 6/16.
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);
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#else // 8
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const float threshold[64] = float[64](
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1/64.,33/64., 9/64.,41/64., 3/64.,35/64.,11/64.,43/64.,
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49/64.,17/64.,57/64.,25/64.,51/64.,19/64.,59/64.,27/64.,
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13/64.,45/64., 5/64.,37/64.,15/64.,47/64., 7/64.,39/64.,
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61/64.,29/64.,53/64.,21/64.,63/64.,31/64.,55/64.,23/64.,
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4/64.,36/64.,12/64.,42/64., 2/64.,34/64.,10/64.,42/64.,
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52/64.,20/64.,60/64.,28/64.,50/64.,18/64.,58/64.,26/64.,
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16/64.,48/64., 8/64.,40/64.,14/64.,46/64., 6/64.,38/64.,
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64/64.,32/64.,56/64.,24/64.,62/64.,30/64.,54/64.,22/64.
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);
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#endif
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void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
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vec2 uv = fragCoord/iResolution.xy;
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vec4 src = texture(iChannel0, uv);
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int x = int(fragCoord.x) % BAYER;
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int y = int(fragCoord.y) % BAYER;
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float luma = dot(vec3(0.2126, 0.7152, 0.0722), src.rgb);
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luma = step(threshold[BAYER*x+y], luma); // find closest
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fragColor = vec4(vec3(luma), src.a);
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}
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