Helper or Intersections between lines and planes
Forks
Forks pushed to more recently than robandrose/ofxIntersection itself, plus any admin-confirmed fork with commits of its own — worth checking if you're hitting issues with the original.
README
ofxIntersection
Helper for Intersections between lines and planes
based on http://paulbourke.net/geometry/pointlineplane/
Triangles:

Lines:

Planes:

ofxAddons