rimworld-animation-studio/Library/PackageCache/com.unity.mathematics@1.1.0/Unity.Mathematics/Noise/cellular2x2.cs
2022-09-13 00:36:34 -05:00

46 lines
1.9 KiB
C#

// Cellular noise ("Worley noise") in 2D in GLSL.
// Copyright (c) Stefan Gustavson 2011-04-19. All rights reserved.
// This code is released under the conditions of the MIT license.
// See LICENSE file for details.
// https://github.com/stegu/webgl-noise
using static Unity.Mathematics.math;
namespace Unity.Mathematics
{
public static partial class noise
{
// Cellular noise, returning F1 and F2 in a float2.
// Speeded up by umath.sing 2x2 search window instead of 3x3,
// at the expense of some strong pattern artifacts.
// F2 is often wrong and has sharp discontinuities.
// If you need a smooth F2, use the slower 3x3 version.
// F1 is sometimes wrong, too, but OK for most purposes.
public static float2 cellular2x2(float2 P)
{
const float K = 0.142857142857f; // 1/7
const float K2 = 0.0714285714285f; // K/2
const float jitter = 0.8f; // jitter 1.0 makes F1 wrong more often
float2 Pi = mod289(floor(P));
float2 Pf = frac(P);
float4 Pfx = Pf.x + float4(-0.5f, -1.5f, -0.5f, -1.5f);
float4 Pfy = Pf.y + float4(-0.5f, -0.5f, -1.5f, -1.5f);
float4 p = permute(Pi.x + float4(0.0f, 1.0f, 0.0f, 1.0f));
p = permute(p + Pi.y + float4(0.0f, 0.0f, 1.0f, 1.0f));
float4 ox = mod7(p) * K + K2;
float4 oy = mod7(floor(p * K)) * K + K2;
float4 dx = Pfx + jitter * ox;
float4 dy = Pfy + jitter * oy;
float4 d = dx * dx + dy * dy; // d11, d12, d21 and d22, squared
// Sort out the two smallest distances
// Do it right and find both F1 and F2
d.xy = (d.x < d.y) ? d.xy : d.yx; // Swap if smaller
d.xz = (d.x < d.z) ? d.xz : d.zx;
d.xw = (d.x < d.w) ? d.xw : d.wx;
d.y = min(d.y, d.z);
d.y = min(d.y, d.w);
return sqrt(d.xy);
}
}
}