62 lines
2.7 KiB
C#
62 lines
2.7 KiB
C#
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// Cellular noise ("Worley noise") in 2D in GLSL.
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// Copyright (c) Stefan Gustavson 2011-04-19. All rights reserved.
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// This code is released under the conditions of the MIT license.
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// See LICENSE file for details.
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// https://github.com/stegu/webgl-noise
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using static Unity.Mathematics.math;
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namespace Unity.Mathematics
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{
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public static partial class noise
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{
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/// <summary>
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/// 2D Cellular noise ("Worley noise") with standard 3x3 search window for good feature point values.
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/// </summary>
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/// <param name="P">A point in 2D space.</param>
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/// <returns>Feature points. F1 is in the x component, F2 in the y component.</returns>
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public static float2 cellular(float2 P)
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{
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const float K = 0.142857142857f; // 1/7
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const float Ko = 0.428571428571f; // 3/7
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const float jitter = 1.0f; // Less gives more regular pattern
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float2 Pi = mod289(floor(P));
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float2 Pf = frac(P);
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float3 oi = float3(-1.0f, 0.0f, 1.0f);
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float3 of = float3(-0.5f, 0.5f, 1.5f);
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float3 px = permute(Pi.x + oi);
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float3 p = permute(px.x + Pi.y + oi); // p11, p12, p13
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float3 ox = frac(p * K) - Ko;
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float3 oy = mod7(floor(p * K)) * K - Ko;
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float3 dx = Pf.x + 0.5f + jitter * ox;
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float3 dy = Pf.y - of + jitter * oy;
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float3 d1 = dx * dx + dy * dy; // d11, d12 and d13, squared
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p = permute(px.y + Pi.y + oi); // p21, p22, p23
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ox = frac(p * K) - Ko;
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oy = mod7(floor(p * K)) * K - Ko;
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dx = Pf.x - 0.5f + jitter * ox;
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dy = Pf.y - of + jitter * oy;
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float3 d2 = dx * dx + dy * dy; // d21, d22 and d23, squared
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p = permute(px.z + Pi.y + oi); // p31, p32, p33
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ox = frac(p * K) - Ko;
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oy = mod7(floor(p * K)) * K - Ko;
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dx = Pf.x - 1.5f + jitter * ox;
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dy = Pf.y - of + jitter * oy;
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float3 d3 = dx * dx + dy * dy; // d31, d32 and d33, squared
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// Sort out the two smallest distances (F1, F2)
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float3 d1a = min(d1, d2);
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d2 = max(d1, d2); // Swap to keep candidates for F2
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d2 = min(d2, d3); // neither F1 nor F2 are now in d3
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d1 = min(d1a, d2); // F1 is now in d1
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d2 = max(d1a, d2); // Swap to keep candidates for F2
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d1.xy = (d1.x < d1.y) ? d1.xy : d1.yx; // Swap if smaller
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d1.xz = (d1.x < d1.z) ? d1.xz : d1.zx; // F1 is in d1.x
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d1.yz = min(d1.yz, d2.yz); // F2 is now not in d2.yz
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d1.y = min(d1.y, d1.z); // nor in d1.z
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d1.y = min(d1.y, d2.x); // F2 is in d1.y, we're done.
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return sqrt(d1.xy);
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}
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}
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}
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