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50 lines
1.7 KiB
50 lines
1.7 KiB
#ifndef __CELLULAE_2X2__
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#define __CELLULAE_2X2__
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#include "noiseMath.cginc"
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// 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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// Cellular noise, returning F1 and F2 in a vec2.
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// Speeded up by using 2x2 search window instead of 3x3,
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// at the expense of some strong pattern artifacts.
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// F2 is often wrong and has sharp discontinuities.
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// If you need a smooth F2, use the slower 3x3 version.
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// F1 is sometimes wrong, too, but OK for most purposes.
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float2 cellular2x2(float2 P) {
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const float K = 0.142857142857; // 1/7
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const float K2 = 0.0714285714285; // K/2
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const float jitter = 0.8; // jitter 1.0 makes F1 wrong more often
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float2 Pi = mod289(floor(P));
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float2 Pf = fract(P);
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float4 Pfx = Pf.x + vec4(-0.5, -1.5, -0.5, -1.5);
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float4 Pfy = Pf.y + vec4(-0.5, -0.5, -1.5, -1.5);
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float4 p = permute(Pi.x + vec4(0.0, 1.0, 0.0, 1.0));
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p = permute(p + Pi.y + vec4(0.0, 0.0, 1.0, 1.0));
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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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#if false
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// Cheat and pick only F1
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d.xy = min(d.xy, d.zw);
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d.x = min(d.x, d.y);
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return vec2(sqrt(d.x)); // F1 duplicated, F2 not computed
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#else
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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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#endif
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}
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#endif |