89 lines
2.6 KiB
JavaScript
89 lines
2.6 KiB
JavaScript
import {epsilon} from "../math.js";
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import {Cardinal} from "./cardinal.js";
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export function point(that, x, y) {
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var x1 = that._x1,
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y1 = that._y1,
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x2 = that._x2,
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y2 = that._y2;
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if (that._l01_a > epsilon) {
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var a = 2 * that._l01_2a + 3 * that._l01_a * that._l12_a + that._l12_2a,
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n = 3 * that._l01_a * (that._l01_a + that._l12_a);
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x1 = (x1 * a - that._x0 * that._l12_2a + that._x2 * that._l01_2a) / n;
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y1 = (y1 * a - that._y0 * that._l12_2a + that._y2 * that._l01_2a) / n;
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}
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if (that._l23_a > epsilon) {
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var b = 2 * that._l23_2a + 3 * that._l23_a * that._l12_a + that._l12_2a,
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m = 3 * that._l23_a * (that._l23_a + that._l12_a);
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x2 = (x2 * b + that._x1 * that._l23_2a - x * that._l12_2a) / m;
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y2 = (y2 * b + that._y1 * that._l23_2a - y * that._l12_2a) / m;
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}
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that._context.bezierCurveTo(x1, y1, x2, y2, that._x2, that._y2);
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}
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function CatmullRom(context, alpha) {
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this._context = context;
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this._alpha = alpha;
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}
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CatmullRom.prototype = {
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areaStart: function() {
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this._line = 0;
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},
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areaEnd: function() {
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this._line = NaN;
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},
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lineStart: function() {
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this._x0 = this._x1 = this._x2 =
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this._y0 = this._y1 = this._y2 = NaN;
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this._l01_a = this._l12_a = this._l23_a =
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this._l01_2a = this._l12_2a = this._l23_2a =
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this._point = 0;
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},
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lineEnd: function() {
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switch (this._point) {
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case 2: this._context.lineTo(this._x2, this._y2); break;
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case 3: this.point(this._x2, this._y2); break;
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}
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if (this._line || (this._line !== 0 && this._point === 1)) this._context.closePath();
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this._line = 1 - this._line;
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},
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point: function(x, y) {
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x = +x, y = +y;
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if (this._point) {
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var x23 = this._x2 - x,
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y23 = this._y2 - y;
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this._l23_a = Math.sqrt(this._l23_2a = Math.pow(x23 * x23 + y23 * y23, this._alpha));
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}
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switch (this._point) {
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case 0: this._point = 1; this._line ? this._context.lineTo(x, y) : this._context.moveTo(x, y); break;
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case 1: this._point = 2; break;
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case 2: this._point = 3; // falls through
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default: point(this, x, y); break;
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}
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this._l01_a = this._l12_a, this._l12_a = this._l23_a;
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this._l01_2a = this._l12_2a, this._l12_2a = this._l23_2a;
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this._x0 = this._x1, this._x1 = this._x2, this._x2 = x;
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this._y0 = this._y1, this._y1 = this._y2, this._y2 = y;
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}
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};
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export default (function custom(alpha) {
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function catmullRom(context) {
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return alpha ? new CatmullRom(context, alpha) : new Cardinal(context, 0);
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}
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catmullRom.alpha = function(alpha) {
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return custom(+alpha);
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};
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return catmullRom;
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})(0.5);
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