Mark Schrandt

                /// 

                /// Represents the physics-based  AimIndicator.
                /// 
                public override void Update(GameTime gameTime)
                {
                    base.Update(gameTime);
                    if (!IsAiming) return;

                    _aimTimer += (float)gameTime.ElapsedGameTime.TotalSeconds;
                    IsVisible = true;

                    var dir = new Vector2(MathF.Cos(_rotation), MathF.Sin(_rotation));
                    var vel = dir * InitialSpeed;
                    var dt = (float)gameTime.ElapsedGameTime.TotalSeconds;

                    for (int i = 0; i < DotCount && i < _aimDots.Count; i++)
                    {
                        vel += Gravity * dt;
                        _aimDots[i].Place(position + vel * dt * i * 2);
                    }
                }

                /// 

                /// Represents a physics-based arrow projectile.
                /// 
                public override void Update(GameTime gameTime)
                {
                    var dt = (float)gameTime.ElapsedGameTime.TotalSeconds;
                    // apply gravity
                    _velocity += _gravity * dt;
                    // update position
                    position += _velocity * dt;
                    // update rotation to face movement direction
                    rotation = MathF.Atan2(_velocity.Y, _velocity.X);
                }

                /// 

                /// Shoots an arrow following the current trajectory.
                /// 
                public Arrow Shoot()
                {
                    // calculate initial velocity and direction
                    var dir = new Vector2(MathF.Cos(_rotation), MathF.Sin(_rotation));
                    var initialVelocity = dir * InitialSpeed;
        
                    // create arrow at indicator position
                    var arrow = new Arrow(position, initialVelocity, Gravity);
                    StopAiming();
                    IsVisible = false;
                    return arrow;
                }
              

                // Rotate an object continuously
                void Update() {
                  transform.Rotate(Vector3.up * 20 * Time.deltaTime);
                }