// Based on IQ's gradient noise formula.
private float Noise2D3G(float2 p)
{
float2 i = Hlsl.Floor(p);
p -= i;
float4 v = default;
v.X = Hlsl.Dot(Hash22(i), p);
v.Y = Hlsl.Dot(Hash22(i + float2.UnitX), p - float2.UnitX);
v.Z = Hlsl.Dot(Hash22(i + float2.UnitY), p - float2.UnitY);
v.W = Hlsl.Dot(Hash22(i + 1.0f), p - 1.0f);
p = p * p * p * (p * (p * 6.0f - 15.0f) + 10.0f);
return(Hlsl.Lerp(Hlsl.Lerp(v.X, v.Y, p.X), Hlsl.Lerp(v.Z, v.W, p.X), p.Y));
}
// Smooth 2D noise
private static float Noise2D(float2 p)
{
float2 i = Hlsl.Floor(p);
p -= i;
float4 v = default;
v.X = Hlsl.Dot(Hash22B(i), p);
v.Y = Hlsl.Dot(Hash22B(i + float2.UnitX), p - float2.UnitX);
v.Z = Hlsl.Dot(Hash22B(i + float2.UnitY), p - float2.UnitY);
v.W = Hlsl.Dot(Hash22B(i + 1.0f), p - 1.0f);
p = p * p * (3.0f - 2.0f * p);
return(Hlsl.Lerp(Hlsl.Lerp(v.X, v.Y, p.X), Hlsl.Lerp(v.Z, v.W, p.X), p.Y));
}
/// <inheritdoc/>
public float4 Execute()
{
float2 uv = (ThreadIds.XY - (float2)DispatchSize.XY * 0.5f) / DispatchSize.Y;
float3 col = 0;
float t = time * 0.3f;
for (float i = 0.0f; i <= 1.0f; i += 1.0f / NumberOfLayers)
{
float d = Hlsl.Frac(i + t);
float s = Hlsl.Lerp(5.0f, 0.5f, d);
float f = d * Hlsl.SmoothStep(1.0f, 0.9f, d);
col += Tex(new float3(uv.X * s, uv.Y * s, i * 4.0f)).XYZ *f;
}
col /= NumberOfLayers;
col *= new float3(2, 1.0f, 2.0f);
col = Hlsl.Pow(col, 0.5f);
return(new(col.X, col.Y, col.Z, 1.0f));
}