Thank you so much GLV!!! I think I understand it better now. As a side note / curiosity I noticed that in both, my example and your example, one of the PShapes has a black background slightly visible when it passes the 90 degrees angle. I do not know why, and only it is one of them. both of them have a transparent (no background) PNG as a texture… Do you happen to know why is that the case? find image below:
Thank you again 
PS: Your reply / help / didactic impulse that I was referring to in the initial msg of this thread is this one:
using-pixels-array-over-points-trying-to-moving-pixels-xy-off-screen-like-points/24309
It really blew my mind and opened up the pixels array for me. It is from 2020-10-05.