noise.glsl (1988B)
1 vec4 permute(vec4 x){return mod(((x*34.0)+1.0)*x, 289.0);} 2 vec4 taylorInvSqrt(vec4 r){return 1.79284291400159 - 0.85373472095314 * r;} 3 4 float snoise(vec3 v){ 5 const vec2 C = vec2(1.0/6.0, 1.0/3.0) ; 6 const vec4 D = vec4(0.0, 0.5, 1.0, 2.0); 7 8 // First corner 9 vec3 i = floor(v + dot(v, C.yyy) ); 10 vec3 x0 = v - i + dot(i, C.xxx) ; 11 12 // Other corners 13 vec3 g = step(x0.yzx, x0.xyz); 14 vec3 l = 1.0 - g; 15 vec3 i1 = min( g.xyz, l.zxy ); 16 vec3 i2 = max( g.xyz, l.zxy ); 17 18 // x0 = x0 - 0. + 0.0 * C 19 vec3 x1 = x0 - i1 + 1.0 * C.xxx; 20 vec3 x2 = x0 - i2 + 2.0 * C.xxx; 21 vec3 x3 = x0 - 1. + 3.0 * C.xxx; 22 23 // Permutations 24 i = mod(i, 289.0 ); 25 vec4 p = permute( permute( permute( 26 i.z + vec4(0.0, i1.z, i2.z, 1.0 )) 27 + i.y + vec4(0.0, i1.y, i2.y, 1.0 )) 28 + i.x + vec4(0.0, i1.x, i2.x, 1.0 )); 29 30 // Gradients 31 // ( N*N points uniformly over a square, mapped onto an octahedron.) 32 float n_ = 1.0/7.0; // N=7 33 vec3 ns = n_ * D.wyz - D.xzx; 34 35 vec4 j = p - 49.0 * floor(p * ns.z *ns.z); // mod(p,N*N) 36 37 vec4 x_ = floor(j * ns.z); 38 vec4 y_ = floor(j - 7.0 * x_ ); // mod(j,N) 39 40 vec4 x = x_ *ns.x + ns.yyyy; 41 vec4 y = y_ *ns.x + ns.yyyy; 42 vec4 h = 1.0 - abs(x) - abs(y); 43 44 vec4 b0 = vec4( x.xy, y.xy ); 45 vec4 b1 = vec4( x.zw, y.zw ); 46 47 vec4 s0 = floor(b0)*2.0 + 1.0; 48 vec4 s1 = floor(b1)*2.0 + 1.0; 49 vec4 sh = -step(h, vec4(0.0)); 50 51 vec4 a0 = b0.xzyw + s0.xzyw*sh.xxyy ; 52 vec4 a1 = b1.xzyw + s1.xzyw*sh.zzww ; 53 54 vec3 p0 = vec3(a0.xy,h.x); 55 vec3 p1 = vec3(a0.zw,h.y); 56 vec3 p2 = vec3(a1.xy,h.z); 57 vec3 p3 = vec3(a1.zw,h.w); 58 59 //Normalise gradients 60 vec4 norm = taylorInvSqrt(vec4(dot(p0,p0), dot(p1,p1), dot(p2, p2), dot(p3,p3))); 61 p0 *= norm.x; 62 p1 *= norm.y; 63 p2 *= norm.z; 64 p3 *= norm.w; 65 66 // Mix final noise value 67 vec4 m = max(0.6 - vec4(dot(x0,x0), dot(x1,x1), dot(x2,x2), dot(x3,x3)), 0.0); 68 m = m * m; 69 return 42.0 * dot( m*m, vec4( dot(p0,x0), dot(p1,x1), 70 dot(p2,x2), dot(p3,x3) ) ); 71 }