the-cannon-2_part1_update-cannon.ts

update(dt) {
    const { angleSpeed } = this;

    if (angleSpeed !== 0) {
        const angle = this.angle = MathUtilities.clamp(this.angle + angleSpeed * dt, 
                                                       this.leftMaxAngle * -1, 
                                                       this.rightMaxAngle);
        this.barrel.rotation = angle;
    }
}