The app supplies the heighfield collider with triangles for a given sample patch, so it has no idea what layout these tris are, apart from that they're guaranteed to be axis aligned. I'm looking for the fastest & most elegant way to determine which of the 4 layouts one of those tris is (so I can do a fast 2D point-in-tri test): |\ |_\ _ \ | \| _ | / |/ /| /_| Any ideas? -- gl