矩阵变换和子画面方向的问题

Question

我有一个名为Tool的精灵，它以表示为float的速度和表示为Vector2的方向移动。 当我在屏幕上单击鼠标时，精灵会更改其方向，并开始朝着mouseclick移动。 除此之外，我还要旋转精灵，使其面向前进的方向。 但是，当我添加一个假定要跟随该精灵的摄像机以使该精灵始终位于屏幕中央时，该精灵将不会沿给定方向移动，并且旋转不再精确。 仅当我在spriteBatch.Begin（）中添加Camera.View时才会发生这种情况。 我希望有人能阐明我的代码中缺少的内容，对此将不胜感激。

这是我使用的相机类：

    public class Camera
{
    private const float zoomUpperLimit = 1.5f;
    private const float zoomLowerLimit = 0.1f;

    private float _zoom;
    private Vector2 _pos;

    private int ViewportWidth, ViewportHeight;

    #region Properties

    public float Zoom
    {
        get { return _zoom; }
        set
        {
            _zoom = value;
            if (_zoom < zoomLowerLimit)
                _zoom = zoomLowerLimit;
            if (_zoom > zoomUpperLimit)
                _zoom = zoomUpperLimit;
        }
    }

    public Rectangle Viewport 
    {
        get
        {
            int width = (int)((ViewportWidth / _zoom));
            int height = (int)((ViewportHeight / _zoom));
            return new Rectangle((int)(_pos.X - width / 2), (int)(_pos.Y - height / 2), width, height);
        }
    }

    public void Move(Vector2 amount)
    {
        _pos += amount;
    }

    public Vector2 Position
    {
        get { return _pos; }
        set { _pos = value; }
    }

    public Matrix View
    {
        get
        {
            return Matrix.CreateTranslation(new Vector3(-_pos.X, -_pos.Y, 0)) *
                Matrix.CreateScale(new Vector3(Zoom, Zoom, 1)) *
                    Matrix.CreateTranslation(new Vector3(ViewportWidth * 0.5f, ViewportHeight * 0.5f, 0));
        }
    }

    #endregion

    public Camera(Viewport viewport, float initialZoom)
    {
        _zoom = initialZoom;
        _pos = Vector2.Zero;
        ViewportWidth = viewport.Width;
        ViewportHeight = viewport.Height;
    }

}

这是我的更新和绘制方法：

protected override void Update (GameTime gameTime)
    {
        float elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds;
        TouchCollection touchCollection = TouchPanel.GetState ();

        foreach (TouchLocation tl in touchCollection) {
            if (tl.State == TouchLocationState.Pressed || tl.State == TouchLocationState.Moved) {

                //direction the tool shall move towards
                direction = touchCollection [0].Position - toolPos;

                if (direction != Vector2.Zero) {
                    direction.Normalize ();
                }   

                //change the direction the tool is moving and find the rotationangle the texture must rotate to point in given direction
                toolPos += (direction * speed * elapsed);
                RotationAngle = (float)Math.Atan2 (direction.Y, direction.X);
            }
        }

        if (direction != Vector2.Zero) {
            direction.Normalize ();
        }

        //move tool in given direction
        toolPos += (direction * speed * elapsed);
        //change cameracentre to the tools position
        Camera.Position = toolPos;
        base.Update (gameTime);
    }

        protected override void Draw (GameTime gameTime)
    {
        graphics.GraphicsDevice.Clear (Color.Blue);
        spriteBatch.Begin (SpriteSortMode.BackToFront, BlendState.AlphaBlend, null, null, null, null, Camera.View);
        spriteBatch.Draw (tool, new Vector2 (toolPos.X, toolPos.Y), null, Color.White, RotationAngle, originOfToolTexture, 1, SpriteEffects.None, 1);
        spriteBatch.End ();

        base.Draw (gameTime);
    }

Answer 1

您需要将光标位置转换为世界位置：

Vector2 adjustedPosition = Vector2.Transform(touchCollection[0].Position, Matrix.Invert(camera.View));

那么您的方向将是：

direction = adjustedPosition - toolPos;