# Polygon-ray intersections

## Possible to do the whole calculation using 3d points, but it is more efficient to use 2d points.

## Converting to the coordinates in the plane is computationally expensive. Idea: project to a coordinate plane (XY, YZ, or XZ) by discarding one of the vector coordinates.

## We cannot always discard, say, Z, because the polygon may project to an interval, if it is in a plane parallel to Z.

## Choose the coordinate to discard so that the corresponding component of the normal to the polygon is maximal. E.g. if nx > ny and nx > nz,discard X.