I am trying to understand triangulation, explained in the book "Computational Geometry Algorithms and Applications, 3rd Ed - de Berg et al". Unfortunately, I don't know how to solve the following question:
The pockets of a simple polygon are the areas outside the polygon, but inside its convex hull. Let $P_1$ be a simple polygon with m vertices, and assume that a triangulation of $P_1$ as well as its pockets is given. Let $P_2$ be a convex polygon with n vertices. Show that the intersection $P_1 \cap P_2$ can be computed in O(m + n) time.
The problem is that I do not know how I can use the triangulation of $P_1$ to calculate the intersection of $P_1$ and $P_2$.