135 lines
4.1 KiB
HLSL
135 lines
4.1 KiB
HLSL
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/******************************************************************************/
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/*
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Project - MudBun
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Publisher - Long Bunny Labs
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http://LongBunnyLabs.com
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Author - Ming-Lun "Allen" Chou
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http://AllenChou.net
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Based on project "webgl-noise" by Ashima Arts.
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Description : Array and textureless GLSL 2D simplex noise function.
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Author : Ian McEwan, Ashima Arts.
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Maintainer : ijm
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Lastmod : 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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*/
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/******************************************************************************/
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#ifndef MUDBUN_SIMPLEX_NOISE_2D
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#define MUDBUN_SIMPLEX_NOISE_2D
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#include "NoiseCommon.cginc"
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// single octave
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float mbn_snoise(float2 v)
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{
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const float4 C = float4( 0.211324865405187, // (3.0-sqrt(3.0))/6.0
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0.366025403784439, // 0.5*(sqrt(3.0)-1.0)
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-0.577350269189626, // -1.0 + 2.0 * C.x
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0.024390243902439); // 1.0 / 41.0
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// First corner
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float2 i = floor(v + dot(v, C.yy));
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float2 x0 = v - i + dot(i, C.xx);
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// Other corners
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float2 i1;
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i1.x = step(x0.y, x0.x);
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i1.y = 1.0 - i1.x;
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// x1 = x0 - i1 + 1.0 * C.xx;
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// x2 = x0 - 1.0 + 2.0 * C.xx;
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float2 x1 = x0 + C.xx - i1;
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float2 x2 = x0 + C.zz;
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// Permutations
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i = mod289(i); // Avoid truncation effects in permutation
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float3 p =
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mbn_permute(mbn_permute(i.y + float3(0.0, i1.y, 1.0))
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+ i.x + float3(0.0, i1.x, 1.0));
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float3 m = max(0.5 - float3(dot(x0, x0), dot(x1, x1), dot(x2, x2)), 0.0);
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m = m * m;
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m = m * m;
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// Gradients: 41 points uniformly over a line, mapped onto a diamond.
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// The ring size 17*17 = 289 is close to a multiple of 41 (41*7 = 287)
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float3 x = 2.0 * frac(p * C.www) - 1.0;
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float3 h = abs(x) - 0.5;
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float3 ox = floor(x + 0.5);
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float3 a0 = x - ox;
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// Normalise gradients implicitly by scaling m
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m *= mbn_taylorInvSqrt(a0 * a0 + h * h);
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// Compute final noise value at P
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float3 g;
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g.x = a0.x * x0.x + h.x * x0.y;
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g.y = a0.y * x1.x + h.y * x1.y;
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g.z = a0.z * x2.x + h.z * x2.y;
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return 130.0 * dot(m, g);
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}
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// multiple octaves
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DEFINE_NOISE_FUNC_MULTIPLE_OCTAVES(mbn_snoise, float, float2, 0.5)
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// single octave
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float3 snoise_grad(float2 v)
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{
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const float4 C = float4( 0.211324865405187, // (3.0-sqrt(3.0))/6.0
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0.366025403784439, // 0.5*(sqrt(3.0)-1.0)
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-0.577350269189626, // -1.0 + 2.0 * C.x
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0.024390243902439); // 1.0 / 41.0
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// First corner
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float2 i = floor(v + dot(v, C.yy));
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float2 x0 = v - i + dot(i, C.xx);
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// Other corners
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float2 i1;
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i1.x = step(x0.y, x0.x);
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i1.y = 1.0 - i1.x;
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// x1 = x0 - i1 + 1.0 * C.xx;
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// x2 = x0 - 1.0 + 2.0 * C.xx;
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float2 x1 = x0 + C.xx - i1;
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float2 x2 = x0 + C.zz;
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// Permutations
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i = mbn_mod289(i); // Avoid truncation effects in permutation
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float3 p =
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mbn_permute(mbn_permute(i.y + float3(0.0, i1.y, 1.0))
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+ i.x + float3(0.0, i1.x, 1.0));
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float3 m = max(0.5 - float3(dot(x0, x0), dot(x1, x1), dot(x2, x2)), 0.0);
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float3 m2 = m * m;
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float3 m3 = m2 * m;
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float3 m4 = m2 * m2;
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// Gradients: 41 points uniformly over a line, mapped onto a diamond.
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// The ring size 17*17 = 289 is close to a multiple of 41 (41*7 = 287)
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float3 x = 2.0 * frac(p * C.www) - 1.0;
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float3 h = abs(x) - 0.5;
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float3 ox = floor(x + 0.5);
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float3 a0 = x - ox;
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// Normalise gradients
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float3 norm = mbn_taylorInvSqrt(a0 * a0 + h * h);
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float2 g0 = float2(a0.x, h.x) * norm.x;
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float2 g1 = float2(a0.y, h.y) * norm.y;
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float2 g2 = float2(a0.z, h.z) * norm.z;
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// Compute noise and gradient at P
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float2 grad =
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-6.0 * m3.x * x0 * dot(x0, g0) + m4.x * g0 +
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-6.0 * m3.y * x1 * dot(x1, g1) + m4.y * g1 +
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-6.0 * m3.z * x2 * dot(x2, g2) + m4.z * g2;
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float3 px = float3(dot(x0, g0), dot(x1, g1), dot(x2, g2));
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return 130.0 * float3(grad, dot(m4, px));
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}
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// multiple octaves
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DEFINE_NOISE_FUNC_MULTIPLE_OCTAVES(snoise_grad, float3, float2, 0.0)
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#endif
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