shake(intensity, duration, axis, onComplete, force) {
		if (this._shake.duration === 0 || force === true) {
			this._shake.intensity = intensity;
			this._shake.duration = duration;
			this._shake.axis = axis || this.AXIS.BOTH;
			this._shake.onComplete =
				typeof onComplete === "function" ? onComplete : undefined;
		}
	}
shake the camera
@param {number} intensity - maximum offset that the screen can be moved
while shaking
@param {number} duration - expressed in milliseconds
@param {number} [axis=me.game.viewport.AXIS.BOTH] - specify on which axis to apply the shake effect (see {@link Camera2d.AXIS})
@param {Function} [onComplete] - callback once shaking effect is over
@param {boolean} [force] - if true this will override the current effect
@example
// shake it baby !
me.game.viewport.shake(10, 500, me.game.viewport.AXIS.BOTH);