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  1.  
  2. /**********************************************************************************/
  3. /**********************************************************************************/
  4.  
  5. /*
  6. * A speed-improved perlin and simplex noise algorithms for 2D.
  7. *
  8. * Based on example code by Stefan Gustavson (stegu@itn.liu.se).
  9. * Optimisations by Peter Eastman (peastman@drizzle.stanford.edu).
  10. * Better rank ordering method by Stefan Gustavson in 2012.
  11. * Converted to Javascript by Joseph Gentle.
  12. *
  13. * Version 2012-03-09
  14. *
  15. * This code was placed in the public domain by its original author,
  16. * Stefan Gustavson. You may use it as you see fit, but
  17. * attribution is appreciated.
  18. *
  19. */
  20.  
  21. (function(global){
  22. var module = global.Noise = {};
  23.  
  24. function Grad(x, y, z) {
  25. this.x = x; this.y = y; this.z = z;
  26. }
  27.  
  28. Grad.prototype.dot2 = function(x, y) {
  29. return this.x*x + this.y*y;
  30. };
  31.  
  32. Grad.prototype.dot3 = function(x, y, z) {
  33. return this.x*x + this.y*y + this.z*z;
  34. };
  35.  
  36. var grad3 = [new Grad(1,1,0),new Grad(-1,1,0),new Grad(1,-1,0),new Grad(-1,-1,0),
  37. new Grad(1,0,1),new Grad(-1,0,1),new Grad(1,0,-1),new Grad(-1,0,-1),
  38. new Grad(0,1,1),new Grad(0,-1,1),new Grad(0,1,-1),new Grad(0,-1,-1)];
  39.  
  40. var p = [151,160,137,91,90,15,
  41. 131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
  42. 190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
  43. 88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
  44. 77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
  45. 102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
  46. 135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
  47. 5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
  48. 223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
  49. 129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
  50. 251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
  51. 49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
  52. 138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180];
  53. // To remove the need for index wrapping, double the permutation table length
  54. var perm = new Array(512);
  55. var gradP = new Array(512);
  56.  
  57. // This isn't a very good seeding function, but it works ok. It supports 2^16
  58. // different seed values. Write something better if you need more seeds.
  59. module.seed = function(seed) {
  60. if(seed > 0 && seed < 1) {
  61. // Scale the seed out
  62. seed *= 65536;
  63. }
  64.  
  65. seed = Math.floor(seed);
  66. if(seed < 256) {
  67. seed |= seed << 8;
  68. }
  69.  
  70. for(var i = 0; i < 256; i++) {
  71. var v;
  72. if (i & 1) {
  73. v = p[i] ^ (seed & 255);
  74. } else {
  75. v = p[i] ^ ((seed>>8) & 255);
  76. }
  77.  
  78. perm[i] = perm[i + 256] = v;
  79. gradP[i] = gradP[i + 256] = grad3[v % 12];
  80. }
  81. };
  82.  
  83. module.seed(Date.now());
  84. //module.seed(0);
  85.  
  86. /*
  87. for(var i=0; i<256; i++) {
  88. perm[i] = perm[i + 256] = p[i];
  89. gradP[i] = gradP[i + 256] = grad3[perm[i] % 12];
  90. }*/
  91.  
  92. // Skewing and unskewing factors for 2, 3, and 4 dimensions
  93. var F2 = 0.5*(Math.sqrt(3)-1);
  94. var G2 = (3-Math.sqrt(3))/6;
  95.  
  96. var F3 = 1/3;
  97. var G3 = 1/6;
  98.  
  99. // 2D simplex noise
  100. module.simplex2 = function(xin, yin) {
  101. var n0, n1, n2; // Noise contributions from the three corners
  102. // Skew the input space to determine which simplex cell we're in
  103. var s = (xin+yin)*F2; // Hairy factor for 2D
  104. var i = Math.floor(xin+s);
  105. var j = Math.floor(yin+s);
  106. var t = (i+j)*G2;
  107. var x0 = xin-i+t; // The x,y distances from the cell origin, unskewed.
  108. var y0 = yin-j+t;
  109. // For the 2D case, the simplex shape is an equilateral triangle.
  110. // Determine which simplex we are in.
  111. var i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords
  112. if(x0>y0) { // lower triangle, XY order: (0,0)->(1,0)->(1,1)
  113. i1=1; j1=0;
  114. } else { // upper triangle, YX order: (0,0)->(0,1)->(1,1)
  115. i1=0; j1=1;
  116. }
  117. // A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
  118. // a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
  119. // c = (3-sqrt(3))/6
  120. var x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
  121. var y1 = y0 - j1 + G2;
  122. var x2 = x0 - 1 + 2 * G2; // Offsets for last corner in (x,y) unskewed coords
  123. var y2 = y0 - 1 + 2 * G2;
  124. // Work out the hashed gradient indices of the three simplex corners
  125. i &= 255;
  126. j &= 255;
  127. var gi0 = gradP[i+perm[j]];
  128. var gi1 = gradP[i+i1+perm[j+j1]];
  129. var gi2 = gradP[i+1+perm[j+1]];
  130. // Calculate the contribution from the three corners
  131. var t0 = 0.5 - x0*x0-y0*y0;
  132. if(t0<0) {
  133. n0 = 0;
  134. } else {
  135. t0 *= t0;
  136. n0 = t0 * t0 * gi0.dot2(x0, y0); // (x,y) of grad3 used for 2D gradient
  137. }
  138. var t1 = 0.5 - x1*x1-y1*y1;
  139. if(t1<0) {
  140. n1 = 0;
  141. } else {
  142. t1 *= t1;
  143. n1 = t1 * t1 * gi1.dot2(x1, y1);
  144. }
  145. var t2 = 0.5 - x2*x2-y2*y2;
  146. if(t2<0) {
  147. n2 = 0;
  148. } else {
  149. t2 *= t2;
  150. n2 = t2 * t2 * gi2.dot2(x2, y2);
  151. }
  152. // Add contributions from each corner to get the final noise value.
  153. // The result is scaled to return values in the interval [-1,1].
  154. return 70 * (n0 + n1 + n2);
  155. };
  156.  
  157.  
  158.  
  159. })(this);
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