getNormalTri :: (Vec3, Vec3, Vec3) -> Vec3
getNormalTri (a, b, c) = let
  ba = b &- a
  ca = c &- a
  in normalize $ ba &^ ca
getNormalTri :: (Vec3, Vec3, Vec3) -> Vec3
getNormalTri (a, b, c) = let
  ba = b &- a
  ca = c &- a
  in normalize $ ba &^ ca
getNormalTri (a, b, c) = let
  ba = b &- a
  ca = c &- a
  in normalize $ ba &^ ca