matrix.js 2.4 KB

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  1. /**
  2. * @fileoverview 矩阵运算,本来是要引入 gl-matrix, 但是考虑到 g-mobile 对大小有限制,同时 g-webgl 使用的 matrix 不一致
  3. * 所以,这里仅实现 2D 几个运算,上层自己引入 gl-matrix
  4. * @author dxq613@gmail.com
  5. */
  6. /**
  7. * 3阶矩阵相乘
  8. * @param {number[]} a 矩阵1
  9. * @param {number[]} b 矩阵2
  10. */
  11. export function multiplyMatrix(a, b) {
  12. var out = [];
  13. var a00 = a[0];
  14. var a01 = a[1];
  15. var a02 = a[2];
  16. var a10 = a[3];
  17. var a11 = a[4];
  18. var a12 = a[5];
  19. var a20 = a[6];
  20. var a21 = a[7];
  21. var a22 = a[8];
  22. var b00 = b[0];
  23. var b01 = b[1];
  24. var b02 = b[2];
  25. var b10 = b[3];
  26. var b11 = b[4];
  27. var b12 = b[5];
  28. var b20 = b[6];
  29. var b21 = b[7];
  30. var b22 = b[8];
  31. out[0] = b00 * a00 + b01 * a10 + b02 * a20;
  32. out[1] = b00 * a01 + b01 * a11 + b02 * a21;
  33. out[2] = b00 * a02 + b01 * a12 + b02 * a22;
  34. out[3] = b10 * a00 + b11 * a10 + b12 * a20;
  35. out[4] = b10 * a01 + b11 * a11 + b12 * a21;
  36. out[5] = b10 * a02 + b11 * a12 + b12 * a22;
  37. out[6] = b20 * a00 + b21 * a10 + b22 * a20;
  38. out[7] = b20 * a01 + b21 * a11 + b22 * a21;
  39. out[8] = b20 * a02 + b21 * a12 + b22 * a22;
  40. return out;
  41. }
  42. /**
  43. * 3阶矩阵同2阶向量相乘
  44. * @param {number[]} m 矩阵
  45. * @param {number[]} v 二阶向量
  46. */
  47. export function multiplyVec2(m, v) {
  48. var out = [];
  49. var x = v[0];
  50. var y = v[1];
  51. out[0] = m[0] * x + m[3] * y + m[6];
  52. out[1] = m[1] * x + m[4] * y + m[7];
  53. return out;
  54. }
  55. /**
  56. * 矩阵的逆
  57. * @param {number[]} a 矩阵
  58. */
  59. export function invert(a) {
  60. var out = [];
  61. var a00 = a[0];
  62. var a01 = a[1];
  63. var a02 = a[2];
  64. var a10 = a[3];
  65. var a11 = a[4];
  66. var a12 = a[5];
  67. var a20 = a[6];
  68. var a21 = a[7];
  69. var a22 = a[8];
  70. var b01 = a22 * a11 - a12 * a21;
  71. var b11 = -a22 * a10 + a12 * a20;
  72. var b21 = a21 * a10 - a11 * a20;
  73. // Calculate the determinant
  74. var det = a00 * b01 + a01 * b11 + a02 * b21;
  75. if (!det) {
  76. return null;
  77. }
  78. det = 1.0 / det;
  79. out[0] = b01 * det;
  80. out[1] = (-a22 * a01 + a02 * a21) * det;
  81. out[2] = (a12 * a01 - a02 * a11) * det;
  82. out[3] = b11 * det;
  83. out[4] = (a22 * a00 - a02 * a20) * det;
  84. out[5] = (-a12 * a00 + a02 * a10) * det;
  85. out[6] = b21 * det;
  86. out[7] = (-a21 * a00 + a01 * a20) * det;
  87. out[8] = (a11 * a00 - a01 * a10) * det;
  88. return out;
  89. }
  90. //# sourceMappingURL=matrix.js.map