This application that can be installed on iPhone and iPad is used to generate 3D perspective views. With it, you can input data to generate furniture, simple rooms, and more complex buildings made of rectangular prisms. In fact, you can also do other things, such as making logos made of rectangular prisms, establishing accurate rectangular outlines of the drawn objects during painting (and then drawing objects in this outline), and serving as a reference for perspective learning (in the case of rectangular prisms in perspective, the y-coordinate is 0 corresponding to the position of draw paper),You can rotate around the x-axis of the image (equivalent to the origin of the local coordinates used for rotation, where the y-coordinate and z-coordinate are 0) to achieve a top-down or bottom-up effect (a positive rotation angle around the x-axis is equivalent to a top-down view, and a negative rotation angle is equivalent to a bottom-up view, generally the rotation angle should not be too large).