HW4

This practice is extremely challenging and complicated for me. Cause I took great efforts trying to figure out the code. It was truly hard at first, but after the teacher explained it step by step, everything was going smoothly. I just need to be careful when using the pointer, and it's a quite useful tool in order to make code clear and simple. It was pretty fun when I turned on the camera and then it came out such amazing effects. I am looking forward to having more practices like this, it's awesome!