Ray Polygon Intersection
A [see page 10, way] to detect whether an arbitrary polygon intersects a ray.
This works by first forming a plane from the polygon (using it's vertices and the polygon normal) and then using ray-plane-intersection and asserting that the intersection point is in the polygon (using [see page 11, barycentric-coordinates]).
We can also calculate the [see page 12, normal] at the intersection point using a combination of each vertex normals.