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93 lines
2.5 KiB
JavaScript
93 lines
2.5 KiB
JavaScript
// Ported from Stefan Gustavson's java implementation
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// http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
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// Sean McCullough banksean@gmail.com
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var SimplexNoise = function(gen) {
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this.rand = gen;
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this.grad3 = [
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[1,1,0],[-1,1,0],[1,-1,0],[-1,-1,0],
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[1,0,1],[-1,0,1],[1,0,-1],[-1,0,-1],
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[0,1,1],[0,-1,1],[0,1,-1],[0,-1,-1]
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];
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this.simplex = [
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[0,1,2,3],[0,1,3,2],[0,0,0,0],[0,2,3,1],[0,0,0,0],[0,0,0,0],[0,0,0,0],[1,2,3,0],
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[0,2,1,3],[0,0,0,0],[0,3,1,2],[0,3,2,1],[0,0,0,0],[0,0,0,0],[0,0,0,0],[1,3,2,0],
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[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0],
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[1,2,0,3],[0,0,0,0],[1,3,0,2],[0,0,0,0],[0,0,0,0],[0,0,0,0],[2,3,0,1],[2,3,1,0],
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[1,0,2,3],[1,0,3,2],[0,0,0,0],[0,0,0,0],[0,0,0,0],[2,0,3,1],[0,0,0,0],[2,1,3,0],
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[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0],
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[2,0,1,3],[0,0,0,0],[0,0,0,0],[0,0,0,0],[3,0,1,2],[3,0,2,1],[0,0,0,0],[3,1,2,0],
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[2,1,0,3],[0,0,0,0],[0,0,0,0],[0,0,0,0],[3,1,0,2],[0,0,0,0],[3,2,0,1],[3,2,1,0]
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];
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};
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SimplexNoise.prototype.setSeed = function(seed) {
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this.p = [];
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this.rand.seed = seed;
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for (var i=0; i<256; i++) {
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this.p[i] = Math.floor(this.rand.nextRange(0, 255));
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}
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this.perm = [];
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for(var i=0; i<512; i++) {
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this.perm[i]=this.p[i & 255];
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}
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}
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SimplexNoise.prototype.dot = function(g, x, y) {
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return g[0]*x + g[1]*y;
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};
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SimplexNoise.prototype.noise = function(xin, yin) {
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var n0, n1, n2;
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var F2 = 0.5*(Math.sqrt(3.0)-1.0);
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var s = (xin+yin)*F2;
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var i = Math.floor(xin+s);
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var j = Math.floor(yin+s);
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var G2 = (3.0-Math.sqrt(3.0))/6.0;
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var t = (i+j)*G2;
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var X0 = i-t;
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var Y0 = j-t;
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var x0 = xin-X0;
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var y0 = yin-Y0;
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var i1, j1;
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if(x0>y0) {i1=1; j1=0;}
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else {i1=0; j1=1;}
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var x1 = x0 - i1 + G2;
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var y1 = y0 - j1 + G2;
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var x2 = x0 - 1.0 + 2.0 * G2;
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var y2 = y0 - 1.0 + 2.0 * G2;
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var ii = i & 255;
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var jj = j & 255;
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var gi0 = this.perm[ii+this.perm[jj]] % 12;
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var gi1 = this.perm[ii+i1+this.perm[jj+j1]] % 12;
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var gi2 = this.perm[ii+1+this.perm[jj+1]] % 12;
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var t0 = 0.5 - x0*x0-y0*y0;
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if(t0<0) n0 = 0.0;
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else {
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t0 *= t0;
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n0 = t0 * t0 * this.dot(this.grad3[gi0], x0, y0);
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}
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var t1 = 0.5 - x1*x1-y1*y1;
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if(t1<0) n1 = 0.0;
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else {
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t1 *= t1;
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n1 = t1 * t1 * this.dot(this.grad3[gi1], x1, y1);
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}
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var t2 = 0.5 - x2*x2-y2*y2;
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if(t2<0) n2 = 0.0;
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else {
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t2 *= t2;
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n2 = t2 * t2 * this.dot(this.grad3[gi2], x2, y2);
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}
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return 70.0 * (n0 + n1 + n2);
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};
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