 Construct a Mesh from vertex coordinates and indices, without any
-- shading geometry.
simpleMesh :: Vector P3D -> Vector (V3 Int) -> Shape
simpleMesh ps vis = Mesh ps vis Nothing Nothing Nothing

--
simpleMesh :: Vector P3D -> Vector (V3 Int) -> Shape
simpleMesh ps vis = Mesh ps vis Nothing Nothing Nothing
simpleMesh ps vis = Mesh ps vis Nothing Nothing Nothing