c# - I Want To Create Quadtree -

i want create quad tree doesn't work correctly. rectangle , divide until width , height greater 1 . doesn't divide correctly. can me? thanks. here code.

public class quadtree {     public treenode mainroot;                 bool switch=false;                               public quadtree(rectangle r)               {         mainroot = new treenode();         mainroot.rectangle = r;         mainroot.leftchild = null;         mainroot.rightchild = null;     }      public void createtree(treenode root, rectangle r)     {         if (root.rectangle.width<=1 || root.rectangle.height <=1)         {             return;         }         root.leftchild = new treenode();         root.rightchild = new treenode();         if (!switch)         {             root.leftchild.rectangle = new rectangle(r.x, r.y, r.width / 2, r.height);             root.rightchild.rectangle = new rectangle(r.x + r.width / 2, r.y, r.width/2, r.height);         }          if (switch)         {             root.leftchild.rectangle = new rectangle(r.x, r.y, r.width, r.height / 2);             root.rightchild.rectangle = new rectangle(r.x, r.y - r.height / 2, r.width, r.height / 2);         }          switch = !switch;         createtree(root.leftchild, root.leftchild.rectangle);         createtree(root.rightchild, root.rightchild.rectangle);     } 

}