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98 lines
3.6 KiB
98 lines
3.6 KiB
// |
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// Description : Array and textureless GLSL 2D/3D/4D simplex |
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// noise functions. |
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// Author : Ian McEwan, Ashima Arts. |
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// Maintainer : stegu |
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// Lastmath.mod : 20110822 (ijm) |
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// License : Copyright (C) 2011 Ashima Arts. All rights reserved. |
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// Distributed under the MIT License. See LICENSE file. |
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// https://github.com/ashima/webgl-noise |
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// https://github.com/stegu/webgl-noise |
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// |
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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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/// Simplex noise. |
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/// </summary> |
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/// <param name="v">Input coordinate.</param> |
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/// <returns>Noise value.</returns> |
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public static float snoise(float3 v) |
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{ |
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float2 C = float2(1.0f / 6.0f, 1.0f / 3.0f); |
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float4 D = float4(0.0f, 0.5f, 1.0f, 2.0f); |
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// First corner |
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float3 i = floor(v + dot(v, C.yyy)); |
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float3 x0 = v - i + dot(i, C.xxx); |
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// Other corners |
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float3 g = step(x0.yzx, x0.xyz); |
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float3 l = 1.0f - g; |
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float3 i1 = min(g.xyz, l.zxy); |
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float3 i2 = max(g.xyz, l.zxy); |
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// x0 = x0 - 0.0 + 0.0 * C.xxx; |
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// x1 = x0 - i1 + 1.0 * C.xxx; |
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// x2 = x0 - i2 + 2.0 * C.xxx; |
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// x3 = x0 - 1.0 + 3.0 * C.xxx; |
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float3 x1 = x0 - i1 + C.xxx; |
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float3 x2 = x0 - i2 + C.yyy; // 2.0*C.x = 1/3 = C.y |
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float3 x3 = x0 - D.yyy; // -1.0+3.0*C.x = -0.5 = -D.y |
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// Permutations |
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i = mod289(i); |
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float4 p = permute(permute(permute( |
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i.z + float4(0.0f, i1.z, i2.z, 1.0f)) |
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+ i.y + float4(0.0f, i1.y, i2.y, 1.0f)) |
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+ i.x + float4(0.0f, i1.x, i2.x, 1.0f)); |
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// Gradients: 7x7 points over a square, mapped onto an octahedron. |
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// The ring size 17*17 = 289 is close to a multiple of 49 (49*6 = 294) |
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float n_ = 0.142857142857f; // 1.0/7.0 |
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float3 ns = n_ * D.wyz - D.xzx; |
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float4 j = p - 49.0f * floor(p * ns.z * ns.z); // math.mod(p,7*7) |
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float4 x_ = floor(j * ns.z); |
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float4 y_ = floor(j - 7.0f * x_); // math.mod(j,N) |
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float4 x = x_ * ns.x + ns.yyyy; |
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float4 y = y_ * ns.x + ns.yyyy; |
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float4 h = 1.0f - abs(x) - abs(y); |
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float4 b0 = float4(x.xy, y.xy); |
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float4 b1 = float4(x.zw, y.zw); |
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//float4 s0 = float4(math.lessThan(b0,0.0))*2.0 - 1.0; |
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//float4 s1 = float4(math.lessThan(b1,0.0))*2.0 - 1.0; |
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float4 s0 = floor(b0) * 2.0f + 1.0f; |
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float4 s1 = floor(b1) * 2.0f + 1.0f; |
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float4 sh = -step(h, float4(0.0f)); |
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float4 a0 = b0.xzyw + s0.xzyw * sh.xxyy; |
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float4 a1 = b1.xzyw + s1.xzyw * sh.zzww; |
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float3 p0 = float3(a0.xy, h.x); |
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float3 p1 = float3(a0.zw, h.y); |
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float3 p2 = float3(a1.xy, h.z); |
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float3 p3 = float3(a1.zw, h.w); |
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//Normalise gradients |
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float4 norm = taylorInvSqrt(float4(dot(p0, p0), dot(p1, p1), dot(p2, p2), dot(p3, p3))); |
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p0 *= norm.x; |
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p1 *= norm.y; |
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p2 *= norm.z; |
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p3 *= norm.w; |
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// Mix final noise value |
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float4 m = max(0.6f - float4(dot(x0, x0), dot(x1, x1), dot(x2, x2), dot(x3, x3)), 0.0f); |
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m = m * m; |
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return 42.0f * dot(m * m, float4(dot(p0, x0), dot(p1, x1), dot(p2, x2), dot(p3, x3))); |
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} |
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} |
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}
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