c# - 回転に基づく XNA 方向

Question

XNA プロジェクトに矢印があり、このコードでマウスの位置に向かって回転させることに成功しました。

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;

namespace Test
{
    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;

        Texture2D arrowSprite;
        float rotation;
        Vector2 direction;
        Vector2 position;
        float speed;
        Vector2 mousePos;
        SpriteFont font1;

        public Game1()
        {
            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";
        }

        /// <summary>
        /// Allows the game to perform any initialization it needs to before starting to run.
        /// This is where it can query for any required services and load any non-graphic
        /// related content.  Calling base.Initialize will enumerate through any components
        /// and initialize them as well.
        /// </summary>
        protected override void Initialize()
        {
            // TODO: Add your initialization logic here
            position = new Vector2(GraphicsDevice.Viewport.Width / 2, GraphicsDevice.Viewport.Height / 5);
            speed = 1000.0f;
            this.IsMouseVisible = true;
            MouseState mouse = Mouse.GetState();
            mousePos.X = mouse.X;
            mousePos.Y = mouse.Y;
            rotation = Angle(position, mousePos);
            base.Initialize();
        }

        /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        protected override void LoadContent()
        {
            // Create a new SpriteBatch, which can be used to draw textures.
            spriteBatch = new SpriteBatch(GraphicsDevice);
            arrowSprite = Content.Load<Texture2D>("Sprites\\Arrow");
            font1 = Content.Load<SpriteFont>("Sprites\\Test");
            // TODO: use this.Content to load your game content here
        }

        /// <summary>
        /// UnloadContent will be called once per game and is the place to unload
        /// all content.
        /// </summary>
        protected override void UnloadContent()
        {
            // TODO: Unload any non ContentManager content here
        }

        /// <summary>
        /// Allows the game to run logic such as updating the world,
        /// checking for collisions, gathering input, and playing audio.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Update(GameTime gameTime)
        {
            // Allows the game to exit
            if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
                this.Exit();

            // TODO: Add your update logic here
            MouseState mouse = Mouse.GetState();
            mousePos.X = mouse.X;
            mousePos.Y = mouse.Y;
            rotation = Angle(position, mousePos);
            direction = new Vector2((float)Math.Cos(rotation), (float)Math.Sin(rotation));
            position += direction * 10.0f * (float)gameTime.ElapsedGameTime.TotalSeconds;
            base.Update(gameTime);
        }

        /// <summary>
        /// This is called when the game should draw itself.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);

            // TODO: Add your drawing code here
            spriteBatch.Begin();
            spriteBatch.Draw(arrowSprite, position, null, Color.White, rotation, new Vector2(arrowSprite.Width / 2, arrowSprite.Height / 2), 1.0f, SpriteEffects.None, 1.0f);
            spriteBatch.DrawString(font1, mousePos.X.ToString()+ " " + mousePos.Y.ToString(), new Vector2(GraphicsDevice.Viewport.Width / 2, 0), Color.White);
            //spriteBatch.DrawString(font1, "Rotation:" + rotation.ToString(), Vector2.Zero, Color.White);
            spriteBatch.DrawString(font1, "Direction" + direction.ToString(), Vector2.Zero, Color.White);
            spriteBatch.End();
            base.Draw(gameTime);
        }

        public static float Angle(Vector2 from, Vector2 to)
        {
            return (float)Math.Atan2(from.X - to.X, to.Y - from.Y);
        }
    }
}

ただし、コードを実行すると、矢印はマウスの周りを回転するだけで、その半径は時間の経過とともにわずかに拡大します。矢印がマウスに向かって回転し、回転先の領域に向かって移動することを望みます。ありがとう、助けていただければ幸いです。