@awayfl/awayfl-player/lib/Box2D/Common/Math/b2Mat22.ts

Flash Player emulator for executing SWF files (published for FP versions 6 and up) in javascript

import { b2Vec2 } from '../Math';

/**
* A 2-by-2 matrix. Stored in column-major order.
*/
export class b2Mat22 {
	readonly __fast__ = true;

	constructor() {
		this.col1.x = this.col2.y = 1.0;
	}

	public static FromAngle(angle: number): b2Mat22 {
		const mat: b2Mat22 = new b2Mat22();
		mat.Set(angle);
		return mat;
	}

	public static FromVV(c1: b2Vec2, c2: b2Vec2): b2Mat22 {
		const mat: b2Mat22 = new b2Mat22();
		mat.SetVV(c1, c2);
		return mat;
	}

	public Set(angle: number): void {
		const c: number = Math.cos(angle);
		const s: number = Math.sin(angle);
		this.col1.x = c; this.col2.x = -s;
		this.col1.y = s; this.col2.y = c;
	}

	public SetVV(c1: b2Vec2, c2: b2Vec2): void {
		this.col1.SetV(c1);
		this.col2.SetV(c2);
	}

	public Copy(): b2Mat22 {
		const mat: b2Mat22 = new b2Mat22();
		mat.SetM(this);
		return mat;
	}

	public SetM(m: b2Mat22): void {
		//@ts-ignore
		this.col1.SetV(m.col1 || m.$Bgcol1);
		//@ts-ignore
		this.col2.SetV(m.col2 || m.$Bgcol2);
	}

	public AddM(m: b2Mat22): void {
		this.col1.x += m.col1.x;
		this.col1.y += m.col1.y;
		this.col2.x += m.col2.x;
		this.col2.y += m.col2.y;
	}

	public SetIdentity(): void {
		this.col1.x = 1.0; this.col2.x = 0.0;
		this.col1.y = 0.0; this.col2.y = 1.0;
	}

	public SetZero(): void {
		this.col1.x = 0.0; this.col2.x = 0.0;
		this.col1.y = 0.0; this.col2.y = 0.0;
	}

	public GetAngle(): number {
		return Math.atan2(this.col1.y, this.col1.x);
	}

	/**
     * Compute the inverse of this matrix, such that inv(A) * A = identity.
     */
	public GetInverse(out: b2Mat22): b2Mat22 {
		const a: number = this.col1.x;
		const b: number = this.col2.x;
		const c: number = this.col1.y;
		const d: number = this.col2.y;
		//var B:b2Mat22 = new b2Mat22();
		let det: number = a * d - b * c;
		if (det != 0.0) {
			det = 1.0 / det;
		}
		out.col1.x =  det * d;	out.col2.x = -det * b;
		out.col1.y = -det * c;	out.col2.y =  det * a;
		return out;
	}

	// Solve A * x = b
	public Solve(out: b2Vec2, bX: number, bY: number): b2Vec2 {
		//float32 a11 = col1.x, a12 = col2.x, a21 = col1.y, a22 = col2.y;
		const a11: number = this.col1.x;
		const a12: number = this.col2.x;
		const a21: number = this.col1.y;
		const a22: number = this.col2.y;
		//float32 det = a11 * a22 - a12 * a21;
		let det: number = a11 * a22 - a12 * a21;
		if (det != 0.0) {
			det = 1.0 / det;
		}
		out.x = det * (a22 * bX - a12 * bY);
		out.y = det * (a11 * bY - a21 * bX);

		return out;
	}

	public Abs(): void {
		this.col1.Abs();
		this.col2.Abs();
	}

	public col1: b2Vec2 = new b2Vec2();
	public col2: b2Vec2 = new b2Vec2();
}