class Bullet extends els.Component{
    @select("C",["A","B","C","D"])
    speed: number;
    accelerate: number;
    @input()
    gravity: number;
    @els.input()
    angle: number;

    test: number = 100;
    test4: number = 100;
    test5: number = 100;
    test6: number = 1000;

    private _dx: number = 0;
    private _dy: number = 0;
    private _lastX: number;
    private _lastY: number;
    private _travelled: number = 0;
    private _radian: number;
    constructor() {
        super();
    }

    create() {
        var inst: els.GameObject        = this.gameobject;
        this._radian                    = els.MathUtils.toRadian(this.angle);
        this._dx                        = Math.cos(this._radian) * this.speed;
        this._dy                        = Math.sin(this._radian) * this.speed;
        this._lastX                     = inst.x;
        this._lastY                     = inst.y;
        this._travelled                 = 0;
    }

    tick(): void{
        var inst: els.GameObject    = this.gameobject;
        var dt: number              = 1 / 60;
        var s: number, a: number;
        if (this.accelerate !== 0) {
            s = new els.Vector2D(this._dx, this._dy).length;
            if (this._dx === 0 && this._dy === 0)
                a = this._radian;
            else
                a = Math.atan2(this._dy, this._dx);
            s += this.accelerate * dt;
            if (s < 0)
                s = 0;
            this._dx = Math.cos(a) * s;
            this._dy = Math.sin(a) * s;

            if (this.gravity !== 0)
                this._dy += this.gravity * dt;
            this._lastX = inst.x;
            this._lastY = inst.y;

            if (this._dx !== 0 || this._dy !== 0) {
                inst.x += this._dx * dt;
                inst.y += this._dy * dt;
                this._travelled += new els.Vector2D(this._dx * dt, this._dy * dt).length;
            }
        }
    }
}