42 lines
961 B
GLSL
42 lines
961 B
GLSL
//!HOOK LUMA
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//!BIND HOOKED
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//!DESC gaussian film grain
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#normal value is 0.05 changed for demo purposes
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#define INTENSITY 0.55
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float permute(float x)
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{
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x = (34.0 * x + 1.0) * x;
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return fract(x * 1.0/289.0) * 289.0;
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}
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float rand(inout float state)
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{
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state = permute(state);
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return fract(state * 1.0/41.0);
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}
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vec4 hook()
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{
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vec3 m = vec3(HOOKED_pos, random) + vec3(1.0);
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float state = permute(permute(m.x) + m.y) + m.z;
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const float a0 = 0.151015505647689;
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const float a1 = -0.5303572634357367;
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const float a2 = 1.365020122861334;
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const float b0 = 0.132089632343748;
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const float b1 = -0.7607324991323768;
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float p = 0.95 * rand(state) + 0.025;
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float q = p - 0.5;
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float r = q * q;
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float grain = q * (a2 + (a1 * r + a0) / (r*r + b1*r + b0));
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grain *= 0.255121822830526; // normalize to [-1,1)
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vec4 color = HOOKED_tex(HOOKED_pos);
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color.rgb += vec3(INTENSITY * grain);
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return color;
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}
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