75 lines
2.5 KiB
JavaScript
75 lines
2.5 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports["default"] = void 0;
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var _vecks = require("vecks");
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/**
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* Create the arcs point for a LWPOLYLINE. The start and end are excluded
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*
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* See diagram.png in this directory for description of points and angles used.
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*/
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var _default = function _default(from, to, bulge, resolution) {
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// Resolution in degrees
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if (!resolution) {
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resolution = 5;
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}
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// If the bulge is < 0, the arc goes clockwise. So we simply
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// reverse a and b and invert sign
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// Bulge = tan(theta/4)
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var theta;
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var a;
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var b;
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if (bulge < 0) {
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theta = Math.atan(-bulge) * 4;
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a = new _vecks.V2(from[0], from[1]);
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b = new _vecks.V2(to[0], to[1]);
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} else {
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// Default is counter-clockwise
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theta = Math.atan(bulge) * 4;
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a = new _vecks.V2(to[0], to[1]);
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b = new _vecks.V2(from[0], from[1]);
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}
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var ab = b.sub(a);
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var lengthAB = ab.length();
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var c = a.add(ab.multiply(0.5));
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// Distance from center of arc to line between form and to points
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var lengthCD = Math.abs(lengthAB / 2 / Math.tan(theta / 2));
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var normAB = ab.norm();
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var d;
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if (theta < Math.PI) {
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var normDC = new _vecks.V2(normAB.x * Math.cos(Math.PI / 2) - normAB.y * Math.sin(Math.PI / 2), normAB.y * Math.cos(Math.PI / 2) + normAB.x * Math.sin(Math.PI / 2));
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// D is the center of the arc
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d = c.add(normDC.multiply(-lengthCD));
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} else {
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var normCD = new _vecks.V2(normAB.x * Math.cos(Math.PI / 2) - normAB.y * Math.sin(Math.PI / 2), normAB.y * Math.cos(Math.PI / 2) + normAB.x * Math.sin(Math.PI / 2));
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// D is the center of the arc
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d = c.add(normCD.multiply(lengthCD));
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}
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// Add points between start start and eng angle relative
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// to the center point
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var startAngle = Math.atan2(b.y - d.y, b.x - d.x) / Math.PI * 180;
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var endAngle = Math.atan2(a.y - d.y, a.x - d.x) / Math.PI * 180;
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if (endAngle < startAngle) {
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endAngle += 360;
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}
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var r = b.sub(d).length();
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var startInter = Math.floor(startAngle / resolution) * resolution + resolution;
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var endInter = Math.ceil(endAngle / resolution) * resolution - resolution;
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var points = [];
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for (var i = startInter; i <= endInter; i += resolution) {
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points.push(d.add(new _vecks.V2(Math.cos(i / 180 * Math.PI) * r, Math.sin(i / 180 * Math.PI) * r)));
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}
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// Maintain the right ordering to join the from and to points
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if (bulge < 0) {
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points.reverse();
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}
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return points.map(function (p) {
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return [p.x, p.y];
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});
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};
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exports["default"] = _default; |