/*
   Complex grain shader ported over from MariENB
   (C)2012-2022 Marisa the Magician

   Edited for reduced texture sampling (3 fetches instead of 6).
*/
const float nf = .0005;
const vec3 nm = vec3(2.05,3.11,2.22);
const float np = 3.95;
const float bnp = 1.7;

#define darkmask(a,b) (a>0.5)?(2.0*a*(0.5+b)):(1.0-2.0*(1.0-a)*(1.0-((0.5+b))))

vec3 grain( in vec3 res, in vec2 coord )
{
	float ts = Timer*nf;
	float nx = texture(NoiseTexture,coord*nm.x+vec2(ts,0.)).x;
	float ny = texture(NoiseTexture,coord*nm.y+vec2(0.,ts)).x;
	float n = clamp(texture(NoiseTexture,vec2(nx,ny)*nm.z+vec2(ts,ts)).x,0.,1.);
	float nt = pow(n,np);
	float bn = 1.-clamp((res.r+res.g+res.b)/3.,0.,1.);
	bn = pow(bn,bnp);
	res.rgb += vec3(nt*bn*ni);
	return res;
}

void main()
{
	vec2 coord = TexCoord;
	vec4 res = texture(InputTexture,coord);
	vec2 sfact = max(vec2(640.,400.),vec2(textureSize(InputTexture,0))*.5);
	coord = floor(coord*sfact)/sfact;
	res.rgb = grain(res.rgb,coord);
	FragColor = res;
}