tvd :: (GLfloat, GLfloat, GLfloat) -> Vertex3 GLdouble
tvd (x, y, z) = Vertex3 (realToFrac x) (realToFrac y) (realToFrac z)
tvd :: (GLfloat, GLfloat, GLfloat) -> Vertex3 GLdouble
tvd (x, y, z) = Vertex3 (realToFrac x) (realToFrac y) (realToFrac z)
tvd (x, y, z) = Vertex3 (realToFrac x) (realToFrac y) (realToFrac z)