update() {
		// apply timer.tick to delta time for linear interpolation (when enabled)
		// #761 add delta time in body update
		const deltaTime = /* dt * */ timer.tick;

		// apply force if defined
		if (this.force.x !== 0) {
			this.vel.x += this.force.x * deltaTime;
		}
		if (this.force.y !== 0) {
			this.vel.y += this.force.y * deltaTime;
		}

		// apply friction if defined
		if (this.friction.x > 0) {
			const fx = this.friction.x * deltaTime;
			const nx = this.vel.x + fx;
			const x = this.vel.x - fx;

			this.vel.x = nx < 0 ? nx : x > 0 ? x : 0;
		}
		if (this.friction.y > 0) {
			const fy = this.friction.y * deltaTime;
			const ny = this.vel.y + fy;
			const y = this.vel.y - fy;

			this.vel.y = ny < 0 ? ny : y > 0 ? y : 0;
		}

		// cap velocity
		if (this.vel.y !== 0) {
			this.vel.y = clamp(this.vel.y, -this.maxVel.y, this.maxVel.y);
		}
		if (this.vel.x !== 0) {
			this.vel.x = clamp(this.vel.x, -this.maxVel.x, this.maxVel.x);
		}

		// check if falling / jumping
		this.falling = this.vel.y * Math.sign(this.force.y) > 0;
		this.jumping = this.falling ? false : this.jumping;

		// update the body ancestor position
		this.ancestor.pos.add(this.vel);

		// returns true if vel is different from 0
		return this.vel.x !== 0 || this.vel.y !== 0;
	}
Updates the parent's position as well as computes the new body's velocity based
on the values of force/friction.  Velocity chages are proportional to the
me.timer.tick value (which can be used to scale velocities).  The approach to moving the
parent renderable is to compute new values of the Body.vel property then add them to
the parent.pos value thus changing the postion the amount of Body.vel each time the
update call is made. <br>
Updates to Body.vel are bounded by maxVel (which defaults to viewport size if not set) <br>
At this time a call to Body.Update does not call the onBodyUpdate callback that is listed in the constructor arguments.
@protected
@param {number} dt - time since the last update in milliseconds.
@returns {boolean} true if resulting velocity is different than 0