mirror of
https://github.com/RetroDECK/Duckstation.git
synced 2025-04-10 19:15:14 +00:00
74 lines
3.4 KiB
HLSL
74 lines
3.4 KiB
HLSL
////////////////////////////////////////////////////////////////////////////////
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// Triangular Dither //
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// By The Sandvich Maker //
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// Ported to ReShade by TreyM //
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////////////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////////////
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// //
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// Usage: //
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// Include this file in your shader like so: #include "TriDither.fx" //
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// //
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// For shader developers, use this syntax to do a function call in your //
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// code as the last thing before exiting a given shader. You should dither //
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// anytime data is going to be truncated to a lower bitdepth. Color input //
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// must be a float3 value. //
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// //
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// input.rgb += TriDither(input.rgb, uv, bits); //
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// //
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// "bits" is an integer number that determines the bit depth //
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// being dithered to. Usually 8, sometimes 10 //
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// You can automate this by letting Reshade decide like so: //
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// //
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// input += TriDither(input, uv, BUFFER_COLOR_BIT_DEPTH); //
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// //
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// Manual setup looks something like this for an 8-bit backbuffer: //
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// //
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// input.rgb += TriDither(input.rgb, uv, 8); //
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// //
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////////////////////////////////////////////////////////////////////////////////
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uniform float DitherTimer < source = "timer"; >;
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#define remap(v, a, b) (((v) - (a)) / ((b) - (a)))
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float rand21(float2 uv)
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{
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float2 noise = frac(sin(dot(uv, float2(12.9898, 78.233) * 2.0)) * 43758.5453);
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return (noise.x + noise.y) * 0.5;
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}
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float rand11(float x)
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{
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return frac(x * 0.024390243);
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}
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float permute(float x)
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{
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return ((34.0 * x + 1.0) * x) % 289.0;
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}
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float3 TriDither(float3 color, float2 uv, int bits)
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{
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float bitstep = exp2(bits) - 1.0;
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float lsb = 1.0 / bitstep;
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float lobit = 0.5 / bitstep;
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float hibit = (bitstep - 0.5) / bitstep;
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float3 m = float3(uv, rand21(uv + (DitherTimer * 0.001))) + 1.0;
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float h = permute(permute(permute(m.x) + m.y) + m.z);
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float3 noise1, noise2;
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noise1.x = rand11(h); h = permute(h);
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noise2.x = rand11(h); h = permute(h);
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noise1.y = rand11(h); h = permute(h);
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noise2.y = rand11(h); h = permute(h);
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noise1.z = rand11(h); h = permute(h);
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noise2.z = rand11(h);
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float3 lo = saturate(remap(color.xyz, 0.0, lobit));
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float3 hi = saturate(remap(color.xyz, 1.0, hibit));
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float3 uni = noise1 - 0.5;
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float3 tri = noise1 - noise2;
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return lerp(uni, tri, min(lo, hi)) * lsb;
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}
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