100 lines
4.0 KiB
C#
100 lines
4.0 KiB
C#
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//
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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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public static float snoise(float4 v)
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{
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// (math.sqrt(5) - 1)/4 = F4, used once below
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const float F4 = 0.309016994374947451f;
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float4 C = float4( 0.138196601125011f, // (5 - math.sqrt(5))/20 G4
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0.276393202250021f, // 2 * G4
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0.414589803375032f, // 3 * G4
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-0.447213595499958f); // -1 + 4 * G4
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// First corner
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float4 i = floor(v + dot(v, float4(F4)) );
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float4 x0 = v - i + dot(i, C.xxxx);
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// Other corners
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// Rank sorting originally contributed by Bill Licea-Kane, AMD (formerly ATI)
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float4 i0 = float4(0.0f);
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float3 isX = step( x0.yzw, x0.xxx );
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float3 isYZ = step( x0.zww, x0.yyz );
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// i0.x = math.dot( isX, float3( 1.0 ) );
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i0.x = isX.x + isX.y + isX.z;
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i0.yzw = 1.0f - isX;
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// i0.y += math.dot( isYZ.xy, float2( 1.0 ) );
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i0.y += isYZ.x + isYZ.y;
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i0.zw += 1.0f - isYZ.xy;
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i0.z += isYZ.z;
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i0.w += 1.0f - isYZ.z;
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// i0 now contains the unique values 0,1,2,3 in each channel
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float4 i3 = clamp( i0, 0.0f, 1.0f );
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float4 i2 = clamp( i0-1.0f, 0.0f, 1.0f );
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float4 i1 = clamp( i0-2.0f, 0.0f, 1.0f );
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// x0 = x0 - 0.0 + 0.0 * C.xxxx
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// x1 = x0 - i1 + 1.0 * C.xxxx
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// x2 = x0 - i2 + 2.0 * C.xxxx
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// x3 = x0 - i3 + 3.0 * C.xxxx
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// x4 = x0 - 1.0 + 4.0 * C.xxxx
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float4 x1 = x0 - i1 + C.xxxx;
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float4 x2 = x0 - i2 + C.yyyy;
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float4 x3 = x0 - i3 + C.zzzz;
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float4 x4 = x0 + C.wwww;
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// Permutations
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i = mod289(i);
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float j0 = permute( permute( permute( permute(i.w) + i.z) + i.y) + i.x);
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float4 j1 = permute( permute( permute( permute (
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i.w + float4(i1.w, i2.w, i3.w, 1.0f ))
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+ i.z + float4(i1.z, i2.z, i3.z, 1.0f ))
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+ i.y + float4(i1.y, i2.y, i3.y, 1.0f ))
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+ i.x + float4(i1.x, i2.x, i3.x, 1.0f ));
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// Gradients: 7x7x6 points over a cube, mapped onto a 4-cross polytope
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// 7*7*6 = 294, which is close to the ring size 17*17 = 289.
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float4 ip = float4(1.0f/294.0f, 1.0f/49.0f, 1.0f/7.0f, 0.0f) ;
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float4 p0 = grad4(j0, ip);
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float4 p1 = grad4(j1.x, ip);
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float4 p2 = grad4(j1.y, ip);
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float4 p3 = grad4(j1.z, ip);
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float4 p4 = grad4(j1.w, ip);
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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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p4 *= taylorInvSqrt(dot(p4,p4));
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// Mix contributions from the five corners
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float3 m0 = max(0.6f - float3(dot(x0,x0), dot(x1,x1), dot(x2,x2)), 0.0f);
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float2 m1 = max(0.6f - float2(dot(x3,x3), dot(x4,x4) ), 0.0f);
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m0 = m0 * m0;
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m1 = m1 * m1;
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return 49.0f * ( dot(m0*m0, float3( dot( p0, x0 ), dot( p1, x1 ), dot( p2, x2 )))
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+ dot(m1*m1, float2( dot( p3, x3 ), dot( p4, x4 ) ) ) ) ;
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}
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}
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}
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