arcade-physics
Version:
Use Arcade Physics without Phaser.
65 lines • 2.51 kB
JavaScript
;
/**
* @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 Vector2_1 = __importDefault(require("../../math/Vector2"));
// Adapted from http://bjornharrtell.github.io/jsts/doc/api/jsts_geom_Triangle.js.html
/**
* Computes the determinant of a 2x2 matrix. Uses standard double-precision arithmetic, so is susceptible to round-off error.
*
* @function det
* @private
* @since 3.0.0
*
* @param {number} m00 - The [0,0] entry of the matrix.
* @param {number} m01 - The [0,1] entry of the matrix.
* @param {number} m10 - The [1,0] entry of the matrix.
* @param {number} m11 - The [1,1] entry of the matrix.
*
* @return {number} the determinant.
*/
function det(m00, m01, m10, m11) {
return m00 * m11 - m01 * m10;
}
/**
* Computes the circumcentre of a triangle. The circumcentre is the centre of
* the circumcircle, the smallest circle which encloses the triangle. It is also
* the common intersection point of the perpendicular bisectors of the sides of
* the triangle, and is the only point which has equal distance to all three
* vertices of the triangle.
*
* @function Phaser.Geom.Triangle.CircumCenter
* @since 3.0.0
*
* @generic {Phaser.Math.Vector2} O - [out,$return]
*
* @param {Phaser.Geom.Triangle} triangle - The Triangle to get the circumcenter of.
* @param {Phaser.Math.Vector2} [out] - The Vector2 object to store the position in. If not given, a new Vector2 instance is created.
*
* @return {Phaser.Math.Vector2} A Vector2 object holding the coordinates of the circumcenter of the Triangle.
*/
const CircumCenter = (triangle, out) => {
if (out === undefined) {
out = new Vector2_1.default();
}
const cx = triangle.x3;
const cy = triangle.y3;
const ax = triangle.x1 - cx;
const ay = triangle.y1 - cy;
const bx = triangle.x2 - cx;
const by = triangle.y2 - cy;
const denom = 2 * det(ax, ay, bx, by);
const numx = det(ay, ax * ax + ay * ay, by, bx * bx + by * by);
const numy = det(ax, ax * ax + ay * ay, bx, bx * bx + by * by);
out.x = cx - numx / denom;
out.y = cy + numy / denom;
return out;
};
exports.default = CircumCenter;
//# sourceMappingURL=CircumCenter.js.map