arcade-physics/lib/geom/intersects/GetLineToLine.js

Use Arcade Physics without Phaser.

"use strict";
/**
 * @author       Richard Davey
 * @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 Vector3_1 = __importDefault(require("../../math/Vector3"));
/**
 * Checks for intersection between the two line segments and returns the intersection point as a Vector3,
 * or `null` if the lines are parallel, or do not intersect.
 *
 * The `z` property of the Vector3 contains the intersection distance, which can be used to find
 * the closest intersecting point from a group of line segments.
 *
 * @function Phaser.Geom.Intersects.GetLineToLine
 * @since 3.50.0
 *
 * @param {Phaser.Geom.Line} line1 - The first line segment to check.
 * @param {Phaser.Geom.Line} line2 - The second line segment to check.
 * @param {Phaser.Math.Vector3} [out] - A Vector3 to store the intersection results in.
 *
 * @return {Phaser.Math.Vector3} A Vector3 containing the intersection results, or `null`.
 */
const GetLineToLine = (line1, line2, out) => {
    const x1 = line1.x1;
    const y1 = line1.y1;
    const x2 = line1.x2;
    const y2 = line1.y2;
    const x3 = line2.x1;
    const y3 = line2.y1;
    const x4 = line2.x2;
    const y4 = line2.y2;
    const dx1 = x2 - x1;
    const dy1 = y2 - y1;
    const dx2 = x4 - x3;
    const dy2 = y4 - y3;
    const denom = dy2 * dx1 - dx2 * dy1;
    //  Make sure there is not a division by zero - this also indicates that the lines are parallel.
    //  If numA and numB were both equal to zero the lines would be on top of each other (coincidental).
    //  This check is not done because it is not necessary for this implementation (the parallel check accounts for this).
    if (dx1 === 0 || denom === 0) {
        return false;
    }
    const T2 = (dx1 * (y3 - y1) + dy1 * (x1 - x3)) / (dx2 * dy1 - dy2 * dx1);
    const T1 = (x3 + dx2 * T2 - x1) / dx1;
    //  Intersects?
    if (T1 < 0 || T2 < 0 || T2 > 1) {
        return null;
    }
    if (out === undefined) {
        out = new Vector3_1.default();
    }
    return out.set(x1 + dx1 * T1, y1 + dy1 * T1, T1);
};
exports.default = GetLineToLine;
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