arcade-physics/lib/geom/polygon/GetPoints.js

Use Arcade Physics without Phaser.

"use strict";
/**
 * @author       Richard Davey <rich@photonstorm.com>
 * @copyright    2020 Photon Storm Ltd.
 * @license      {@link https://opensource.org/licenses/MIT|MIT License}
 */
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
const Length_1 = __importDefault(require("../line/Length"));
const Line_1 = __importDefault(require("../line/Line"));
const Perimeter_1 = __importDefault(require("./Perimeter"));
/**
 * Returns an array of Point objects containing the coordinates of the points around the perimeter of the Polygon,
 * based on the given quantity or stepRate values.
 *
 * @function Phaser.Geom.Polygon.GetPoints
 * @since 3.12.0
 *
 * @param {Phaser.Geom.Polygon} polygon - The Polygon to get the points from.
 * @param {number} quantity - The amount of points to return. If a falsey value the quantity will be derived from the `stepRate` instead.
 * @param {number} [stepRate] - Sets the quantity by getting the perimeter of the Polygon and dividing it by the stepRate.
 * @param {array} [output] - An array to insert the points in to. If not provided a new array will be created.
 *
 * @return {Phaser.Geom.Point[]} An array of Point objects pertaining to the points around the perimeter of the Polygon.
 */
const GetPoints = (polygon, quantity, stepRate, out) => {
    if (out === undefined) {
        out = [];
    }
    const points = polygon.points;
    const perimeter = (0, Perimeter_1.default)(polygon);
    //  If quantity is a falsey value (false, null, 0, undefined, etc) then we calculate it based on the stepRate instead.
    if (!quantity && stepRate > 0) {
        quantity = perimeter / stepRate;
    }
    for (let i = 0; i < quantity; i++) {
        const position = perimeter * (i / quantity);
        let accumulatedPerimeter = 0;
        for (let j = 0; j < points.length; j++) {
            const pointA = points[j];
            const pointB = points[(j + 1) % points.length];
            const line = new Line_1.default(pointA.x, pointA.y, pointB.x, pointB.y);
            const length = (0, Length_1.default)(line);
            if (position < accumulatedPerimeter || position > accumulatedPerimeter + length) {
                accumulatedPerimeter += length;
                continue;
            }
            const point = line.getPoint((position - accumulatedPerimeter) / length);
            out.push(point);
            break;
        }
    }
    return out;
};
exports.default = GetPoints;
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