-- | A ray defined for t ∈ 0...∞.
mkRay :: P3D -> V3D -> Spectrum -> Ray
mkRay p u s = Ray p u nonNegative s

--
mkRay :: P3D -> V3D -> Spectrum -> Ray
mkRay p u s = Ray p u nonNegative s
mkRay p u s = Ray p u nonNegative s