// Parameters from our host
// x: #sceneid.#scenetime (float)
// y: undefined
// z: Snare drum intensity (amiga ball radius gain)
// w: undefined
uniform vec4 Z; 

float rnd(vec2 p)
{
	p.x += p.y * 57.;
	return sin(cos(p.x) * p.x);
}

float scale;
vec2 hash( vec2 p )
{
	p = mod(p, scale);
	p = vec2( dot(p,vec2(127.1,311.7)),
			  dot(p,vec2(269.5,183.3)) );

	return -1.0 + 2.0*fract(sin(p)*43758.5453123);
}

float noise( in vec2 p, float s )
{
	scale = s;
	p *= s;
    vec2 i = floor( p );
    vec2 f = fract( p );
	
	vec2 u = f*f*(3.0-2.0*f);

    return mix( mix( dot( hash( i + vec2(0.0,0.0) ), f - vec2(0.0,0.0) ), 
                     dot( hash( i + vec2(1.0,0.0) ), f - vec2(1.0,0.0) ), u.x),
                mix( dot( hash( i + vec2(0.0,1.0) ), f - vec2(0.0,1.0) ), 
                     dot( hash( i + vec2(1.0,1.0) ), f - vec2(1.0,1.0) ), u.x), u.y);
}

float voronoi(vec2 p)
{
	p = mod(p, 1.0);
	float min1 = 1, min2 = 1; float seed = 10; const int numPoints = 256;
	for (int i = 0; i < numPoints; ++i)
	{
		vec2 pointPos = vec2(rnd(vec2(0, seed++)), rnd(vec2(1, seed++)))*.5+.5;
		//pointPos += vec2(sin(Z.z+rnd(vec2(0, seed++))), cos(Z.z+rnd(vec2(1, seed++))))*0.1;
		vec2 d = abs(p - pointPos);
		vec2 s = step(0.5, d);
		d = s+d*(-s*2+1);
		float dist = length(d);
		if (dist < min2)
		{
			if (dist < min1)
			{
				min2 = min1;
				min1 = dist;
			}
			else
			{
				min2 = dist;
			}
		}
	}

	//return pow(1.0 - (min2 - min1), 32.0);
	return (min2 - min1) * 8.0;
}

void main()
{
	vec2 p = gl_FragCoord.xy / Z.xy;
	float l = voronoi(p);
	
	float f = 0.5;
	float seed = 10.0;
	for (float t = 2.0; t <= Z.x; t *= 2.0)
	{
		f += (0.5 / pow(t, 0.6)) * noise(p,t);
	}
	gl_FragColor = vec4(l,f,l,1);
}