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我是一名尝试 C# 的 C++ 程序员。我在 c++ 中使用 box2d 做了很多工作，但这是我第一次使用 c#。所以，我正在尝试用 farseer 物理引擎制作一个简单的游戏。当我尝试编译我的代码时（我使用的是 Visual Studio C# 2010 Express 和 XNA Game Studio 4.0），它在 body.cs 中停止，并出现IBroadPhase broadPhase = World.ContactManager.BroadPhase;此错误：nullreferenceexception was unhandled。我相信问题出在我的 Player 类中，所以这里是代码：

public class Player : Entity
{
    Vector2 position;
    SpriteBatch spriteBatch;
    Texture2D texture;
    Rectangle rectangle;
    Body body;
    CircleShape shape;
    Fixture fixture;
    public Player()
    {
        // TODO: Construct any child components here
    }

    /// 
    /// Allows the game component to perform any initialization it needs to before starting
    /// to run.  This is where it can query for any required services and load content.
    /// 
    public override void Initialize(World world, SpriteBatch spriteBatch, Texture2D texture)
    {
        // TODO: Add your initialization code here
        this.spriteBatch = spriteBatch;
        this.texture = texture;
        rectangle = new Rectangle(0, 0, 11, 14);
        body = BodyFactory.CreateBody(world);
        body.BodyType = BodyType.Dynamic;
        body.Position = new Vector2(0, 0);
        shape = new CircleShape(1.0f, 1.0f);
        fixture = body.CreateFixture(shape);
        base.Initialize(world, spriteBatch, texture);
    }

    /// 
    /// Allows the game component to update itself.
    /// 
    /// <param name="gameTime" />Provides a snapshot of timing values.
    public override void Update(GameTime gameTime)
    {
        // TODO: Add your update code here

        base.Update(gameTime);
    }

    public override void Draw(GameTime gameTime)
    {
        spriteBatch.Begin();
        spriteBatch.Draw(texture, new Vector2(body.WorldCenter.X * 10, body.WorldCenter.Y * 10), rectangle, Color.White);
        spriteBatch.End();
        base.Draw(gameTime);
    }
}

farseer 测试平台运行良好，所以我很确定我的代码是问题所在，而不是 farseer。如果您需要查看我的更多代码，请告诉我。我也在farseer论坛上发布了这个，所以如果我在那里得到答案，我会告诉你们。提前致谢。

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1 回答 1

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有人让我展示Game1.cs的代码，发现了问题。问题是我在初始化我的播放器之前从未构建过这个世界。world = new World(Vector2.Zero);在我初始化播放器之前通过添加来修复它。

于 2011-10-08T05:34:30.427 回答