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vdr-plugin-softhdcuvid/shaders/filmgrain.glsl

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961 B
GLSL

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