检查点是否在旋转的矩形内 [英] Checking if a point is inside a rotated rectangle

问题描述

我知道这个问题以前曾被问过几次，而且我已阅读过有关这方面的各种帖子。不过，我正努力让这个工作。

  bool isClicked（）
 {
 Vector2 origLoc = Location; 
 Matrix rotationMatrix = Matrix.CreateRotationZ（-Rotation）; 
 Location = new Vector2（0  - （Texture.Width / 2），0  - （Texture.Height / 2））; 
 Vector2 rotatedPoint = new Vector2（Game1.mouseState.X，Game1.mouseState.Y）; 
 rotatePoint = Vector2.Transform（rotatedPoint，rotationMatrix）; 
 
 if（Game1.mouseState.LeftButton == ButtonState.Pressed&& 
 rotatedPoint.X> Location.X&& 
 rotatePoint.X< Location .X + Texture.Width&& 
 rotatePoint.Y> Location.Y&& 
 rotatePoint.Y< Location.Y + Texture.Height）
 {
 Location = origLoc; 
返回true; 
} 
 Location = origLoc; 
返回false; 
 
  

解决方案

（x1，y1）， B（x2，y2） （x4，y4），

• 计算△APD ，△DPC ，△CPB ，△PBA 。




• 如果这个总和大于矩形的面积：
  
  

  
  
  • 然后点 P（x，y）在 外 。
  em>矩形。
  

每个三角形的面积可以仅使用使用此公式进行坐标：

假设三点是： A（x，y）， B（x，y）， C（x，y）。

<$ （Bx * Ay-Ax * By）+（Cx * Bx-Bx * Cx）+（Ax * Cy-Cx * Ay））/ 2

I know this question has been asked a few times before, and I have read various posts about this. However I am struggling to get this to work.

    bool isClicked()
    {
        Vector2 origLoc = Location;
        Matrix rotationMatrix = Matrix.CreateRotationZ(-Rotation);
        Location = new Vector2(0 -(Texture.Width/2), 0 - (Texture.Height/2));
        Vector2 rotatedPoint = new Vector2(Game1.mouseState.X, Game1.mouseState.Y);
        rotatedPoint = Vector2.Transform(rotatedPoint, rotationMatrix);

        if (Game1.mouseState.LeftButton == ButtonState.Pressed &&
            rotatedPoint.X > Location.X &&
            rotatedPoint.X < Location.X + Texture.Width &&
            rotatedPoint.Y > Location.Y &&
            rotatedPoint.Y < Location.Y + Texture.Height)
        {
            Location = origLoc;
            return true;
        }
        Location = origLoc;
        return false;
    }

解决方案

Let point P(x,y), and rectangle A(x1,y1), B(x2,y2), C(x3,y3), D(x4,y4).

• Calculate the sum of areas of △APD, △DPC, △CPB, △PBA.

• If this sum is greater than the area of the rectangle:

  • Then point P(x,y) is outside the rectangle.
  • Else it is in or on the rectangle.

The area of each triangle can be calculated using only coordinates with this formula:

Assuming the three points are: A(x,y), B(x,y), C(x,y).

Area = abs( (Bx * Ay - Ax * By) + (Cx * Bx - Bx * Cx) + (Ax * Cy - Cx * Ay) ) / 2

这篇关于检查点是否在旋转的矩形内的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！