2 // Description : Array and textureless GLSL 2D/3D/4D simplex
4 // Author : Ian McEwan, Ashima Arts.
6 // Lastmod : 20110822 (ijm)
7 // License : Copyright (C) 2011 Ashima Arts. All rights reserved.
8 // Distributed under the MIT License. See LICENSE file.
9 // https://github.com/ashima/webgl-noise
13 return x - floor(x * (1.0 / 289.0)) * 289.0;
17 return x - floor(x * (1.0 / 289.0)) * 289.0;
20 vec4 permute(vec4 x) {
21 return mod289(((x*34.0)+1.0)*x);
24 vec4 taylorInvSqrt(vec4 r)
26 return 1.79284291400159 - 0.85373472095314 * r;
31 const vec2 C = vec2(1.0/6.0, 1.0/3.0) ;
32 const vec4 D = vec4(0.0, 0.5, 1.0, 2.0);
35 vec3 i = floor(v + dot(v, C.yyy) );
36 vec3 x0 = v - i + dot(i, C.xxx) ;
39 vec3 g = step(x0.yzx, x0.xyz);
41 vec3 i1 = min( g.xyz, l.zxy );
42 vec3 i2 = max( g.xyz, l.zxy );
44 // x0 = x0 - 0.0 + 0.0 * C.xxx;
45 // x1 = x0 - i1 + 1.0 * C.xxx;
46 // x2 = x0 - i2 + 2.0 * C.xxx;
47 // x3 = x0 - 1.0 + 3.0 * C.xxx;
48 vec3 x1 = x0 - i1 + C.xxx;
49 vec3 x2 = x0 - i2 + C.yyy; // 2.0*C.x = 1/3 = C.y
50 vec3 x3 = x0 - D.yyy; // -1.0+3.0*C.x = -0.5 = -D.y
54 vec4 p = permute( permute( permute(
55 i.z + vec4(0.0, i1.z, i2.z, 1.0 ))
56 + i.y + vec4(0.0, i1.y, i2.y, 1.0 ))
57 + i.x + vec4(0.0, i1.x, i2.x, 1.0 ));
59 // Gradients: 7x7 points over a square, mapped onto an octahedron.
60 // The ring size 17*17 = 289 is close to a multiple of 49 (49*6 = 294)
61 float n_ = 0.142857142857; // 1.0/7.0
62 vec3 ns = n_ * D.wyz - D.xzx;
64 vec4 j = p - 49.0 * floor(p * ns.z * ns.z); // mod(p,7*7)
66 vec4 x_ = floor(j * ns.z);
67 vec4 y_ = floor(j - 7.0 * x_ ); // mod(j,N)
69 vec4 x = x_ *ns.x + ns.yyyy;
70 vec4 y = y_ *ns.x + ns.yyyy;
71 vec4 h = 1.0 - abs(x) - abs(y);
73 vec4 b0 = vec4( x.xy, y.xy );
74 vec4 b1 = vec4( x.zw, y.zw );
76 //vec4 s0 = vec4(lessThan(b0,0.0))*2.0 - 1.0;
77 //vec4 s1 = vec4(lessThan(b1,0.0))*2.0 - 1.0;
78 vec4 s0 = floor(b0)*2.0 + 1.0;
79 vec4 s1 = floor(b1)*2.0 + 1.0;
80 vec4 sh = -step(h, vec4(0.0));
82 vec4 a0 = b0.xzyw + s0.xzyw*sh.xxyy ;
83 vec4 a1 = b1.xzyw + s1.xzyw*sh.zzww ;
85 vec3 p0 = vec3(a0.xy,h.x);
86 vec3 p1 = vec3(a0.zw,h.y);
87 vec3 p2 = vec3(a1.xy,h.z);
88 vec3 p3 = vec3(a1.zw,h.w);
91 vec4 norm = taylorInvSqrt(vec4(dot(p0,p0), dot(p1,p1), dot(p2, p2), dot(p3,p3)));
97 // Mix final noise value
98 vec4 m = max(0.6 - vec4(dot(x0,x0), dot(x1,x1), dot(x2,x2), dot(x3,x3)), 0.0);
100 return 42.0 * dot( m*m, vec4( dot(p0,x0), dot(p1,x1),
101 dot(p2,x2), dot(p3,x3) ) );
104 #pragma glslify: export(snoise)