旋转矩阵导致精灵位置改变

Question

我不太精通矩阵数学，所以任何帮助将不胜感激。所以我有一个简单的船精灵，可以旋转和移动。为了计算边界矩形，我尝试使用旋转矩阵和我从这些教程中获得的代码：

http://xbox.create.msdn.com/en-US/education/catalog/tutorial/collision_2d_perpixel

但是每当精灵旋转时，它的边界矩形的 X 和 Y 位置都会发生剧烈变化，大约有 100 像素。新的外接矩形的计算方法如下：

public static Rectangle CalculateBoundingRectangle(Rectangle rectangle, Matrix transform)
    {
        // Get all four corners in local space
        Vector2 leftTop = new Vector2(rectangle.Left, rectangle.Top);
        Vector2 rightTop = new Vector2(rectangle.Right, rectangle.Top);
        Vector2 leftBottom = new Vector2(rectangle.Left, rectangle.Bottom);
        Vector2 rightBottom = new Vector2(rectangle.Right, rectangle.Bottom);

        // Transform all four corners into work space
        Vector2.Transform(ref leftTop, ref transform, out leftTop);
        Vector2.Transform(ref rightTop, ref transform, out rightTop);
        Vector2.Transform(ref leftBottom, ref transform, out leftBottom);
        Vector2.Transform(ref rightBottom, ref transform, out rightBottom);

        // Find the minimum and maximum extents of the rectangle in world space
        Vector2 min = Vector2.Min(Vector2.Min(leftTop, rightTop),
                                  Vector2.Min(leftBottom, rightBottom));
        Vector2 max = Vector2.Max(Vector2.Max(leftTop, rightTop),
                                  Vector2.Max(leftBottom, rightBottom));

        // Return as a rectangle
        return new Rectangle((int)min.X, (int)min.Y,
                             (int)(max.X - min.X), (int)(max.Y - min.Y));
    }

我假设它有效，因为它来自 Microsoft 站点和所有站点。所以我认为问题出在我的矩阵上。我认为如果我只使用旋转矩阵，它只会旋转这个东西；不要大幅改变它的 X 和 Y 坐标。现在这就是我所拥有的：

// calculate transformation
            Matrix transformation = Matrix.CreateRotationZ((float)rotation) * Matrix.CreateRotationZ((float)rotation);;

            //update bounding rectangle
            rectangle = new Rectangle((int)(position.X - origin.X), (int)(position.Y - origin.Y), texture.Width, texture.Height);
            rectangle = BoundingAndCollision.CalculateBoundingRectangle(rectangle, transformation);

我尝试了各种其他方法，包括没有原点矩阵和它们的不同顺序。我还尝试了一个教程所说的通用教程，它适用于任何东西，但产生的结果基本相同：

Matrix transformation = Matrix.CreateTranslation(new Vector3(origin, 0.0f)) *  
                Matrix.CreateRotationZ((float)rotation) * 
                Matrix.CreateScale(scale) * 
                Matrix.CreateTranslation(position.X, position.Y, 0);

如果说的不够清楚我可以post截图，让我know.Thank提前给大家帮忙！

Answer 1

旋转矩阵围绕 0,0 旋转并且您的矩形已经放置在世界中。

求解首先从每个顶点减去矩形的中心（将矩形平移到以0,0为中心）然后在旋转后再次添加它（再次放置在原始位置）。在我假设 Y 从上到下的代码中：

public static Rectangle CalculateBoundingRectangle(Rectangle rectangle, Matrix transform)
{

    Vector2 center = new Vector2(rectangle.Left + (rectangle.Width / 2), rectangle.Top + (rectangle.Height / 2);

    // Get all four corners in local space
    Vector2 leftTop = new Vector2(rectangle.Left, rectangle.Top) - center;
    Vector2 rightTop = new Vector2(rectangle.Right, rectangle.Top) - center;
    Vector2 leftBottom = new Vector2(rectangle.Left, rectangle.Bottom) - center;
    Vector2 rightBottom = new Vector2(rectangle.Right, rectangle.Bottom) - center;

    // Transform all four corners into work space
    Vector2.Transform(ref leftTop, ref transform, out leftTop);
    Vector2.Transform(ref rightTop, ref transform, out rightTop);
    Vector2.Transform(ref leftBottom, ref transform, out leftBottom);
    Vector2.Transform(ref rightBottom, ref transform, out rightBottom);

    leftTop += center;
    rightTop += center;
    leftBottom += center;
    rightBottom += center;

    // Find the minimum and maximum extents of the rectangle in world space
    Vector2 min = Vector2.Min(Vector2.Min(leftTop, rightTop),
                              Vector2.Min(leftBottom, rightBottom));
    Vector2 max = Vector2.Max(Vector2.Max(leftTop, rightTop),
                              Vector2.Max(leftBottom, rightBottom));

    // Return as a rectangle
    return new Rectangle((int)min.X, (int)min.Y,
                         (int)(max.X - min.X), (int)(max.Y - min.Y));
}

旋转矩阵导致精灵位置改变

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