error.hs

-- src/Scene/Object.hs:119:23:
--     Overlapping instances for Num (Exp Position)
--       arising from a use of ‘-’
--     Matching instances:
--       instance (Elt t, IsNum t) => Num (Exp t)
--         -- Defined in ‘accelerate-2.0.0.0:Data.Array.Accelerate.Language’
--       instance (Elt a, IsNum a) => Num (Exp (XYZ a)) -- Defined in ‘Vec3’
--     In the first argument of ‘normalise’, namely
--       ‘((point - spherePos sphere) :: Exp Position)’
--     In the expression:
--       normalise ((point - spherePos sphere) :: Exp Position)
--     In an equation for ‘sphereNormal’:
--         sphereNormal sphere point


--Vec instance
instance (Elt a, IsNum a) => Num (Exp (XYZ a)) where
  (+)   = lift2 ((+) :: XYZ (Exp a) -> XYZ (Exp a) -> XYZ (Exp a))
  (-)   = lift2 ((-) :: XYZ (Exp a) -> XYZ (Exp a) -> XYZ (Exp a))
  (*)   = lift2 ((*) :: XYZ (Exp a) -> XYZ (Exp a) -> XYZ (Exp a))


-- | Compute the surface normal of a sphere at a point
--
sphereNormal
    :: Exp Sphere
    -> Exp Position             -- ^ A point on the surface of the sphere
    -> Exp Direction            -- ^ Normal at that point
sphereNormal sphere point
  = normalise ((point - spherePos sphere) :: Exp Position)