mat4Segment :: Segment -> Mat4
mat4Segment (Segment (Node x y z) (Turn a0 a1 a2 
                                        b0 b1 b2 
                                        c0 c1 c2)) = 
    Mat4 (fI a0) (fI a1) (fI a2) 0
         (fI b0) (fI b1) (fI b2) 0
         (fI c0) (fI c1) (fI c2) 0
         (fI x)  (fI y)  (fI z)  1
mat4Segment :: Segment -> Mat4
mat4Segment (Segment (Node x y z) (Turn a0 a1 a2 
                                        b0 b1 b2 
                                        c0 c1 c2)) = 
    Mat4 (fI a0) (fI a1) (fI a2) 0
         (fI b0) (fI b1) (fI b2) 0
         (fI c0) (fI c1) (fI c2) 0
         (fI x)  (fI y)  (fI z)  1
mat4Segment (Segment (Node x y z) (Turn a0 a1 a2 
                                        b0 b1 b2 
                                        c0 c1 c2)) = 
    Mat4 (fI a0) (fI a1) (fI a2) 0
         (fI b0) (fI b1) (fI b2) 0
         (fI c0) (fI c1) (fI c2) 0
         (fI x)  (fI y)  (fI z)  1