118 lines
3.1 KiB
HLSL
118 lines
3.1 KiB
HLSL
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//
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// GLSL textureless classic 2D noise "cnoise",
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// with an RSL-style periodic variant "pnoise".
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// Author: Stefan Gustavson (stefan.gustavson@liu.se)
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// Version: 2011-08-22
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//
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// Many thanks to Ian McEwan of Ashima Arts for the
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// ideas for permutation and gradient selection.
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//
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// Copyright (c) 2011 Stefan Gustavson. 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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float4 mod(float4 x, float4 y)
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{
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return x - y * floor(x / y);
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}
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float4 mod289(float4 x)
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{
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return x - floor(x / 289.0) * 289.0;
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}
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float4 permute(float4 x)
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{
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return mod289(((x*34.0)+1.0)*x);
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}
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float4 taylorInvSqrt(float4 r)
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{
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return (float4)1.79284291400159 - r * 0.85373472095314;
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}
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float2 fade(float2 t) {
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return t*t*t*(t*(t*6.0-15.0)+10.0);
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}
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// Classic Perlin noise
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float cnoise(float2 P)
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{
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float4 Pi = floor(P.xyxy) + float4(0.0, 0.0, 1.0, 1.0);
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float4 Pf = frac (P.xyxy) - float4(0.0, 0.0, 1.0, 1.0);
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Pi = mod289(Pi); // To avoid truncation effects in permutation
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float4 ix = Pi.xzxz;
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float4 iy = Pi.yyww;
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float4 fx = Pf.xzxz;
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float4 fy = Pf.yyww;
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float4 i = permute(permute(ix) + iy);
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float4 gx = frac(i / 41.0) * 2.0 - 1.0 ;
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float4 gy = abs(gx) - 0.5 ;
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float4 tx = floor(gx + 0.5);
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gx = gx - tx;
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float2 g00 = float2(gx.x,gy.x);
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float2 g10 = float2(gx.y,gy.y);
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float2 g01 = float2(gx.z,gy.z);
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float2 g11 = float2(gx.w,gy.w);
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float4 norm = taylorInvSqrt(float4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11)));
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g00 *= norm.x;
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g01 *= norm.y;
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g10 *= norm.z;
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g11 *= norm.w;
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float n00 = dot(g00, float2(fx.x, fy.x));
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float n10 = dot(g10, float2(fx.y, fy.y));
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float n01 = dot(g01, float2(fx.z, fy.z));
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float n11 = dot(g11, float2(fx.w, fy.w));
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float2 fade_xy = fade(Pf.xy);
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float2 n_x = lerp(float2(n00, n01), float2(n10, n11), fade_xy.x);
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float n_xy = lerp(n_x.x, n_x.y, fade_xy.y);
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return 2.3 * n_xy;
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}
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// Classic Perlin noise, periodic variant
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float pnoise(float2 P, float2 rep)
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{
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float4 Pi = floor(P.xyxy) + float4(0.0, 0.0, 1.0, 1.0);
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float4 Pf = frac (P.xyxy) - float4(0.0, 0.0, 1.0, 1.0);
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Pi = mod(Pi, rep.xyxy); // To create noise with explicit period
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Pi = mod289(Pi); // To avoid truncation effects in permutation
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float4 ix = Pi.xzxz;
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float4 iy = Pi.yyww;
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float4 fx = Pf.xzxz;
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float4 fy = Pf.yyww;
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float4 i = permute(permute(ix) + iy);
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float4 gx = frac(i / 41.0) * 2.0 - 1.0 ;
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float4 gy = abs(gx) - 0.5 ;
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float4 tx = floor(gx + 0.5);
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gx = gx - tx;
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float2 g00 = float2(gx.x,gy.x);
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float2 g10 = float2(gx.y,gy.y);
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float2 g01 = float2(gx.z,gy.z);
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float2 g11 = float2(gx.w,gy.w);
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float4 norm = taylorInvSqrt(float4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11)));
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g00 *= norm.x;
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g01 *= norm.y;
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g10 *= norm.z;
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g11 *= norm.w;
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float n00 = dot(g00, float2(fx.x, fy.x));
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float n10 = dot(g10, float2(fx.y, fy.y));
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float n01 = dot(g01, float2(fx.z, fy.z));
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float n11 = dot(g11, float2(fx.w, fy.w));
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float2 fade_xy = fade(Pf.xy);
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float2 n_x = lerp(float2(n00, n01), float2(n10, n11), fade_xy.x);
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float n_xy = lerp(n_x.x, n_x.y, fade_xy.y);
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return 2.3 * n_xy;
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}
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