Title Text:3D graphs that don’t contact the plane in the closure area may proceed as scheduled, but be alert for possible collisions with 2D graph lines that reach the hole and unexpectedly enter 3D space. Origin:https://xkcd.com/2735/ https://www.explainxkcd.com/wiki/index.php/2735:_Coordinate_Plane_Closure 平面直角坐标系封闭 不会在封闭区域接触到平面的3D图像可以如期作画，但是请小心可能发生的与意外通过这个洞进入3D区域的2D图像线条的碰撞。 htt……