/// <summary>
/// Calculates an axis aligned rectangle which fully contains an arbitrarily
/// transformed axis aligned rectangle.
/// </summary>
/// <param name="rectangle">Original bounding rectangle.</param>
/// <param name="transform">World transform of the rectangle.</param>
/// <returns>A new rectangle which contains the trasnformed rectangle.</returns>
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 that as a rectangle
return new Rectangle((int)min.X, (int)min.Y,
(int)(max.X - min.X), (int)(max.Y - min.Y));
}
المحلول
Assuming code is written correctly both should give the same result.
First - creates bounding rectangle with hardcoded computation for given position/origin and rotation of 0.
Second - is generic way to compute bounding rectangle for given position/origin/rotation (rotation in the sample implied to be 0).
Second approach likely to be used when position/angle already present as transformation matrix.