This optimization can be made systematic. From a polygon-based geometry, an algorithm automatically computes a set of "boxes" (actually, hyperpolyhedra in the g

This optimization can be made systematic. From a polygon-based geometry, an algorithm automatically computes a set of "boxes" (actually, hyperpolyhedra in the general case, polygons in 2D). This allows to very quickly find what intersects any ray without checking all objects. See https://en.wikipedia.org/wiki/Binary_space_partitioning https://en.wikipedia.org/wiki/Binary_space_partitioning It's what enabled Doom to render complex geometry in real time on a i386 processor.