plotboilerplate
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A simple javascript plotting boilerplate for 2d stuff.
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JavaScript
;
/**
* @author Rosettcode, rewritten and ported to TypeScript by Ikaros Kappler
* @date 2020-05-04
* @modified 2020-08-17 Ported this function from vanilla JS to TypeScript.
* @version 1.0.1
*
* @file convexHull
* @public
**/
Object.defineProperty(exports, "__esModule", { value: true });
exports.getConvexHull = void 0;
/**
* @description The Convex Hull algorithm, found at RosettaCode:
*
* https://rosettacode.org/wiki/Convex_hull#JavaScript
*
* @requires XYCoords
*
* @global
* @name convexHull
* @param {Array<XYCoords>} points - The points on the 2D plane to find the convex hull for.
* @return {Array<XYCoords>} A ordered array of points defining the convex hull.
**/
var getConvexHull = function (points) {
points.sort(comparison);
var L = [];
for (var i = 0; i < points.length; i++) {
while (L.length >= 2 && cross(L[L.length - 2], L[L.length - 1], points[i]) <= 0) {
L.pop();
}
L.push(points[i]);
}
var U = [];
for (var i = points.length - 1; i >= 0; i--) {
while (U.length >= 2 && cross(U[U.length - 2], U[U.length - 1], points[i]) <= 0) {
U.pop();
}
U.push(points[i]);
}
L.pop();
U.pop();
return L.concat(U);
};
exports.getConvexHull = getConvexHull;
/**
* Compare two vertices to create an order on the 2D plane.
*
* @name comparison
* @private
* @param {XYCoords} a - The first of the two points to compare.
* @param {XYCoords} b - The second of the two points to compare.
* @return {number} A number indicating the order (negative if `a` is 'smaller', 0 if both are equal, positive if `a` is 'larger').
**/
var comparison = function (a, b) {
return a.x == b.x ? a.y - b.y : a.x - b.x;
};
/**
* Calculate the cross product of the three coordinates, interpreted as vectors.
*
* @name cross
* @private
* @param {XYCoords} a
* @param {XYCoords} b
* @param {XYCoords} o
* @return {number} The cross product of the three 'vectors'.
**/
var cross = function (a, b, o) {
return (a.x - o.x) * (b.y - o.y) - (a.y - o.y) * (b.x - o.x);
};
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