/// <summary>
        /// Handles input, performs physics, and animates the player sprite.
        /// </summary>
        /// <remarks>
        /// We pass in all of the input states so that our game is only polling the hardware
        /// once per frame. We also pass the game's orientation because when using the accelerometer,
        /// we need to reverse our motion when the orientation is in the LandscapeRight orientation.
        /// </remarks>
        public void Update(
            GameTime gameTime,
            KeyboardState keyboardState,
            GamePadState gamePadState,
            AccelerometerState accelState,
            DisplayOrientation orientation)
        {
            GetInput(keyboardState, gamePadState, accelState, orientation);

            ApplyPhysics(gameTime);

            if (IsAlive && IsOnGround)
            {
                if (Math.Abs(Velocity.X) - 0.02f > 0)
                {
                    sprite.PlayAnimation(runAnimation);
                }
                else
                {
                    sprite.PlayAnimation(idleAnimation);
                }
            }

            // Clear input.
            movement  = 0.0f;
            isJumping = false;
        }
        /// <summary>
        /// Gets player horizontal movement and jump commands from input.
        /// </summary>
        private void GetInput(
            KeyboardState keyboardState,
            GamePadState gamePadState,
            AccelerometerState accelState,
            DisplayOrientation orientation)
        {
            // Get analog horizontal movement.
            movement = gamePadState.ThumbSticks.Left.X * MoveStickScale;

            // Ignore small movements to prevent running in place.
            if (Math.Abs(movement) < 0.5f)
            {
                movement = 0.0f;
            }

            // Move the player with accelerometer
            if (Math.Abs(accelState.Acceleration.Y) > 0.10f)
            {
                // set our movement speed
                movement = MathHelper.Clamp(-accelState.Acceleration.Y * AccelerometerScale, -1f, 1f);

                // if we're in the LandscapeLeft orientation, we must reverse our movement
                if (orientation == DisplayOrientation.LandscapeRight)
                {
                    movement = -movement;
                }
            }

            // If any digital horizontal movement input is found, override the analog movement.
            if (gamePadState.IsButtonDown(Buttons.DPadLeft) ||
                keyboardState.IsKeyDown(Keys.Left) ||
                keyboardState.IsKeyDown(Keys.A))
            {
                movement = -1.0f;
            }
            else if (gamePadState.IsButtonDown(Buttons.DPadRight) ||
                     keyboardState.IsKeyDown(Keys.Right) ||
                     keyboardState.IsKeyDown(Keys.D))
            {
                movement = 1.0f;
            }

            // Check if the player wants to jump.
            isJumping =
                gamePadState.IsButtonDown(JumpButton) ||
                keyboardState.IsKeyDown(Keys.Space) ||
                keyboardState.IsKeyDown(Keys.Up) ||
                keyboardState.IsKeyDown(Keys.W);
        }