Predict next position of a polyshape

I have a polygon that is generated at every loop of my code (see images enclosed, with an exemple of 3 polygons). How can I predict the position and the general shape of the next polygon (the 4th) using the precedent ones ? I guess I could make some sort of extrapolation after my code has generated at least 2 polygons but I do not really know how.

[edward holt]

Is it possible to see the code that is creating the polygons?