```{-# LANGUAGE MultiParamTypeClasses, FlexibleInstances #-}
-----------------------------------------------------------------------------------------
-- |
-- Module      :  FRP.Yampa.Point3
-- Copyright   :  (c) Antony Courtney and Henrik Nilsson, Yale University, 2003
--
-- Maintainer  :  nilsson@cs.yale.edu
-- Stability   :  provisional
-- Portability :  non-portable (GHC extensions)
--
-- 3D point abstraction (R^3).
--
-----------------------------------------------------------------------------------------

module FRP.Yampa.Point3 (
-- module AFRPVectorSpace,
-- module AFRPAffineSpace,
-- module AFRPVector3,
Point3(..),	-- Non-abstract, instance of AffineSpace
point3X,	-- :: RealFloat a => Point3 a -> a
point3Y,	-- :: RealFloat a => Point3 a -> a
point3Z	-- :: RealFloat a => Point3 a -> a
) where

import FRP.Yampa.VectorSpace ()
import FRP.Yampa.AffineSpace
import FRP.Yampa.Vector3
import FRP.Yampa.Forceable

------------------------------------------------------------------------------
-- 3D point, constructors and selectors.
------------------------------------------------------------------------------

data RealFloat a => Point3 a = Point3 !a !a !a deriving Eq

point3X :: RealFloat a => Point3 a -> a
point3X (Point3 x _ _) = x

point3Y :: RealFloat a => Point3 a -> a
point3Y (Point3 _ y _) = y

point3Z :: RealFloat a => Point3 a -> a
point3Z (Point3 _ _ z) = z

------------------------------------------------------------------------------
-- Affine space instance
------------------------------------------------------------------------------

instance RealFloat a => AffineSpace (Point3 a) (Vector3 a) a where
origin = Point3 0 0 0

(Point3 x y z) .+^ v =
Point3 (x + vector3X v) (y + vector3Y v) (z + vector3Z v)

(Point3 x y z) .-^ v =
Point3 (x - vector3X v) (y - vector3Y v) (z - vector3Z v)

(Point3 x1 y1 z1) .-. (Point3 x2 y2 z2) =
vector3 (x1 - x2) (y1 - y2) (z1 - z2)

------------------------------------------------------------------------------
-- Forceable instance
------------------------------------------------------------------------------

instance RealFloat a => Forceable (Point3 a) where
force = id
```