49 lines
2.1 KiB
C#
49 lines
2.1 KiB
C#
// 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 a 2x2 search window.
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/// </summary>
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/// <remarks>
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/// Faster than using 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.
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/// </remarks>
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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 cellular2x2(float2 P)
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{
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const float K = 0.142857142857f; // 1/7
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const float K2 = 0.0714285714285f; // K/2
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const float jitter = 0.8f; // jitter 1.0 makes F1 wrong more often
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float2 Pi = mod289(floor(P));
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float2 Pf = frac(P);
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float4 Pfx = Pf.x + float4(-0.5f, -1.5f, -0.5f, -1.5f);
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float4 Pfy = Pf.y + float4(-0.5f, -0.5f, -1.5f, -1.5f);
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float4 p = permute(Pi.x + float4(0.0f, 1.0f, 0.0f, 1.0f));
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p = permute(p + Pi.y + float4(0.0f, 0.0f, 1.0f, 1.0f));
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float4 ox = mod7(p) * K + K2;
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float4 oy = mod7(floor(p * K)) * K + K2;
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float4 dx = Pfx + jitter * ox;
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float4 dy = Pfy + jitter * oy;
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float4 d = dx * dx + dy * dy; // d11, d12, d21 and d22, squared
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// Sort out the two smallest distances
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// Do it right and find both F1 and F2
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d.xy = (d.x < d.y) ? d.xy : d.yx; // Swap if smaller
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d.xz = (d.x < d.z) ? d.xz : d.zx;
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d.xw = (d.x < d.w) ? d.xw : d.wx;
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d.y = min(d.y, d.z);
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d.y = min(d.y, d.w);
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return sqrt(d.xy);
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}
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}
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}
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