Shader "Hidden/Post FX/Grain Generator"
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{
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CGINCLUDE
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#pragma exclude_renderers d3d11_9x
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#pragma target 3.0
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#include "UnityCG.cginc"
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#include "Common.cginc"
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float _Phase;
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// Implementation based on Timothy Lottes' "Large Grain"
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// Reference code: https://www.shadertoy.com/view/4sSXDW
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// Other article of interest: http://devlog-martinsh.blogspot.fr/2013/05/image-imperfections-and-film-grain-post.html
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float Noise(float2 n, float x)
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{
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n += x;
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return frac(sin(dot(n.xy, float2(12.9898, 78.233))) * 43758.5453);
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}
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float Step1(float2 uv, float n)
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{
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float b = 2.0, c = -12.0;
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return (1.0 / (4.0 + b * 4.0 + abs(c))) * (
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Noise(uv + float2(-1.0, -1.0), n) +
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Noise(uv + float2( 0.0, -1.0), n) * b +
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Noise(uv + float2( 1.0, -1.0), n) +
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Noise(uv + float2(-1.0, 0.0), n) * b +
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Noise(uv + float2( 0.0, 0.0), n) * c +
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Noise(uv + float2( 1.0, 0.0), n) * b +
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Noise(uv + float2(-1.0, 1.0), n) +
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Noise(uv + float2( 0.0, 1.0), n) * b +
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Noise(uv + float2( 1.0, 1.0), n)
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);
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}
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float Step2(float2 uv, float n)
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{
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float b = 2.0, c = 4.0;
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return (1.0 / (4.0 + b * 4.0 + abs(c))) * (
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Step1(uv + float2(-1.0, -1.0), n) +
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Step1(uv + float2( 0.0, -1.0), n) * b +
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Step1(uv + float2( 1.0, -1.0), n) +
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Step1(uv + float2(-1.0, 0.0), n) * b +
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Step1(uv + float2( 0.0, 0.0), n) * c +
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Step1(uv + float2( 1.0, 0.0), n) * b +
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Step1(uv + float2(-1.0, 1.0), n) +
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Step1(uv + float2( 0.0, 1.0), n) * b +
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Step1(uv + float2( 1.0, 1.0), n)
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);
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}
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float Step3BW(float2 uv)
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{
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return Step2(uv, frac(_Phase));
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}
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float3 Step3(float2 uv)
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{
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float a = Step2(uv, 0.07 * frac(_Phase));
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float b = Step2(uv, 0.11 * frac(_Phase));
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float c = Step2(uv, 0.13 * frac(_Phase));
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return float3(a, b, c);
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}
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float4 FragGrain(VaryingsDefault i) : SV_Target
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{
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float grain = Step3BW(i.uv * float2(192.0, 192.0));
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return float4(grain.xxx, 1.0);
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}
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float4 FragGrainColored(VaryingsDefault i) : SV_Target
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{
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float3 grain = Step3(i.uv * float2(192.0, 192.0));
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return float4(grain, 1.0);
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}
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ENDCG
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SubShader
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{
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Cull Off ZWrite Off ZTest Always
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Pass
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{
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CGPROGRAM
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#pragma vertex VertDefault
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#pragma fragment FragGrain
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ENDCG
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}
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Pass
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{
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CGPROGRAM
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#pragma vertex VertDefault
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#pragma fragment FragGrainColored
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ENDCG
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}
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}
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}
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