| 1 | import {epsilon} from "../math.js";
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| 2 | import {Cardinal} from "./cardinal.js";
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| 3 |
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| 4 | export function point(that, x, y) {
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| 5 | var x1 = that._x1,
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| 6 | y1 = that._y1,
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| 7 | x2 = that._x2,
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| 8 | y2 = that._y2;
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| 9 |
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| 10 | if (that._l01_a > epsilon) {
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| 11 | var a = 2 * that._l01_2a + 3 * that._l01_a * that._l12_a + that._l12_2a,
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| 12 | n = 3 * that._l01_a * (that._l01_a + that._l12_a);
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| 13 | x1 = (x1 * a - that._x0 * that._l12_2a + that._x2 * that._l01_2a) / n;
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| 14 | y1 = (y1 * a - that._y0 * that._l12_2a + that._y2 * that._l01_2a) / n;
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| 15 | }
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| 16 |
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| 17 | if (that._l23_a > epsilon) {
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| 18 | var b = 2 * that._l23_2a + 3 * that._l23_a * that._l12_a + that._l12_2a,
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| 19 | m = 3 * that._l23_a * (that._l23_a + that._l12_a);
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| 20 | x2 = (x2 * b + that._x1 * that._l23_2a - x * that._l12_2a) / m;
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| 21 | y2 = (y2 * b + that._y1 * that._l23_2a - y * that._l12_2a) / m;
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| 22 | }
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| 23 |
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| 24 | that._context.bezierCurveTo(x1, y1, x2, y2, that._x2, that._y2);
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| 25 | }
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| 26 |
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| 27 | function CatmullRom(context, alpha) {
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| 28 | this._context = context;
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| 29 | this._alpha = alpha;
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| 30 | }
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| 31 |
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| 32 | CatmullRom.prototype = {
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| 33 | areaStart: function() {
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| 34 | this._line = 0;
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| 35 | },
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| 36 | areaEnd: function() {
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| 37 | this._line = NaN;
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| 38 | },
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| 39 | lineStart: function() {
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| 40 | this._x0 = this._x1 = this._x2 =
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| 41 | this._y0 = this._y1 = this._y2 = NaN;
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| 42 | this._l01_a = this._l12_a = this._l23_a =
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| 43 | this._l01_2a = this._l12_2a = this._l23_2a =
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| 44 | this._point = 0;
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| 45 | },
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| 46 | lineEnd: function() {
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| 47 | switch (this._point) {
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| 48 | case 2: this._context.lineTo(this._x2, this._y2); break;
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| 49 | case 3: this.point(this._x2, this._y2); break;
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| 50 | }
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| 51 | if (this._line || (this._line !== 0 && this._point === 1)) this._context.closePath();
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| 52 | this._line = 1 - this._line;
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| 53 | },
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| 54 | point: function(x, y) {
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| 55 | x = +x, y = +y;
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| 56 |
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| 57 | if (this._point) {
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| 58 | var x23 = this._x2 - x,
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| 59 | y23 = this._y2 - y;
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| 60 | this._l23_a = Math.sqrt(this._l23_2a = Math.pow(x23 * x23 + y23 * y23, this._alpha));
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| 61 | }
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| 62 |
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| 63 | switch (this._point) {
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| 64 | case 0: this._point = 1; this._line ? this._context.lineTo(x, y) : this._context.moveTo(x, y); break;
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| 65 | case 1: this._point = 2; break;
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| 66 | case 2: this._point = 3; // falls through
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| 67 | default: point(this, x, y); break;
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| 68 | }
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| 69 |
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| 70 | this._l01_a = this._l12_a, this._l12_a = this._l23_a;
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| 71 | this._l01_2a = this._l12_2a, this._l12_2a = this._l23_2a;
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| 72 | this._x0 = this._x1, this._x1 = this._x2, this._x2 = x;
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| 73 | this._y0 = this._y1, this._y1 = this._y2, this._y2 = y;
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| 74 | }
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| 75 | };
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| 76 |
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| 77 | export default (function custom(alpha) {
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| 78 |
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| 79 | function catmullRom(context) {
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| 80 | return alpha ? new CatmullRom(context, alpha) : new Cardinal(context, 0);
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| 81 | }
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| 82 |
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| 83 | catmullRom.alpha = function(alpha) {
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| 84 | return custom(+alpha);
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| 85 | };
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| 86 |
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| 87 | return catmullRom;
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| 88 | })(0.5);
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