diff --git a/sprout/darkroom/colors/rgb.hpp b/sprout/darkroom/colors/rgb.hpp
index 43cff05e..e944ae8b 100644
--- a/sprout/darkroom/colors/rgb.hpp
+++ b/sprout/darkroom/colors/rgb.hpp
@@ -117,6 +117,14 @@ namespace sprout {
 					sprout::darkroom::colors::b(lhs) * rhs
 					);
 			}
+			template<typename Color, typename Fac, typename... Tail>
+			inline SPROUT_CONSTEXPR Color
+			mul(Color const& lhs, Fac const& rhs, Tail const&... tail) {
+				return sprout::darkroom::colors::mul(
+					sprout::darkroom::colors::mul(lhs, rhs),
+					tail...
+					);
+			}
 			//
 			// add
 			//
@@ -130,6 +138,14 @@ namespace sprout {
 					sprout::darkroom::colors::b(lhs) + sprout::darkroom::colors::b(rhs)
 					);
 			}
+			template<typename Color1, typename Color2, typename... Tail>
+			inline SPROUT_CONSTEXPR Color1
+			add(Color1 const& lhs, Color2 const& rhs, Tail const&... tail) {
+				return sprout::darkroom::colors::add(
+					sprout::darkroom::colors::add(lhs, rhs),
+					tail...
+					);
+			}
 			//
 			// filter
 			//
@@ -143,6 +159,14 @@ namespace sprout {
 					sprout::darkroom::colors::b(lhs) * sprout::darkroom::colors::b(rhs)
 					);
 			}
+			template<typename Color1, typename Color2, typename... Tail>
+			inline SPROUT_CONSTEXPR Color1
+			filter(Color1 const& lhs, Color2 const& rhs, Tail const&... tail) {
+				return sprout::darkroom::colors::filter(
+					sprout::darkroom::colors::filter(lhs, rhs),
+					tail...
+					);
+			}
 
 			//
 			// rgb_f_to_rgb
diff --git a/sprout/darkroom/coords/vector.hpp b/sprout/darkroom/coords/vector.hpp
index 4568e96e..d4fd0303 100644
--- a/sprout/darkroom/coords/vector.hpp
+++ b/sprout/darkroom/coords/vector.hpp
@@ -59,6 +59,17 @@ namespace sprout {
 				return sprout::darkroom::coords::vector3d_t(x, y, z);
 			}
 
+			//
+			// is_zero
+			//
+			template<typename Vector>
+			inline SPROUT_CONSTEXPR bool
+			is_zero(Vector const& vec) {
+				return sprout::darkroom::coords::x(vec) == 0
+					&& sprout::darkroom::coords::y(vec) == 0
+					&& sprout::darkroom::coords::z(vec) == 0
+					;
+			}
 			//
 			// length_sq
 			//
@@ -204,6 +215,37 @@ namespace sprout {
 					sprout::darkroom::coords::scale(nor, sprout::darkroom::coords::dot(incid, nor) * 2)
 					);
 			}
+			//
+			// refract
+			//
+			namespace detail {
+				template<typename Incident, typename Normal, typename Refraction, typename InNor, typename K>
+				inline SPROUT_CONSTEXPR Incident
+				refract_impl_1(Incident const& incid, Normal const& nor, Refraction const& eta, InNor const& t, K const& k) {
+					return k < 0 ? sprout::tuples::remake<Incident>(incid, 0, 0, 0)
+						: sprout::darkroom::coords::sub(
+							sprout::darkroom::coords::scale(incid, eta),
+							sprout::darkroom::coords::scale(nor, eta * t * sprout::sqrt(k))
+							)
+						;
+				}
+				template<typename Incident, typename Normal, typename Refraction, typename InNor>
+				inline SPROUT_CONSTEXPR Incident
+				refract_impl(Incident const& incid, Normal const& nor, Refraction const& eta, InNor const& t) {
+					return sprout::darkroom::coords::detail::refract_impl_1(
+						incid, nor, eta,
+						t, 1 - eta * eta * (1 - t * t)
+						);
+				}
+			}	// namespace detail
+			template<typename Incident, typename Normal, typename Refraction>
+			inline SPROUT_CONSTEXPR Incident
+			refract(Incident const& incid, Normal const& nor, Refraction const& eta) {
+				return sprout::darkroom::coords::detail::refract_impl(
+					incid, nor, eta,
+					sprout::darkroom::coords::dot(incid, nor)
+					);
+			}
 		}	// namespace coords
 	}	// namespace darkroom
 }	// namespace sprout
diff --git a/sprout/darkroom/intersects/intersection.hpp b/sprout/darkroom/intersects/intersection.hpp
index 0335aa89..2f7100ef 100644
--- a/sprout/darkroom/intersects/intersection.hpp
+++ b/sprout/darkroom/intersects/intersection.hpp
@@ -8,6 +8,7 @@
 #ifndef SPROUT_DARKROOM_INTERSECTS_INTERSECTION_HPP
 #define SPROUT_DARKROOM_INTERSECTS_INTERSECTION_HPP
 
+#include <type_traits>
 #include <sprout/config.hpp>
 #include <sprout/tuple/tuple.hpp>
 #include <sprout/utility/forward.hpp>
@@ -89,7 +90,7 @@ namespace sprout {
 			}
 			template<
 				typename T,
-				typename sprout::enabler_if<sprout::darkroom::intersects::has_is_from_inside<T>::value>::type = sprout::enabler
+				typename sprout::enabler_if<sprout::darkroom::intersects::has_is_from_inside<typename std::decay<T>::type>::value>::type = sprout::enabler
 			>
 			inline SPROUT_CONSTEXPR auto
 			is_from_inside(T&& t)
@@ -100,7 +101,7 @@ namespace sprout {
 			}
 			template<
 				typename T,
-				typename sprout::enabler_if<!sprout::darkroom::intersects::has_is_from_inside<T>::value>::type = sprout::enabler
+				typename sprout::enabler_if<!sprout::darkroom::intersects::has_is_from_inside<typename std::decay<T>::type>::value>::type = sprout::enabler
 			>
 			inline SPROUT_CONSTEXPR typename sprout::darkroom::access::element<5, sprout::darkroom::intersects::intersection>::type
 			is_from_inside(T&&)
diff --git a/sprout/darkroom/lights/parallel_light.hpp b/sprout/darkroom/lights/parallel_light.hpp
index cab2069a..0d3b6010 100644
--- a/sprout/darkroom/lights/parallel_light.hpp
+++ b/sprout/darkroom/lights/parallel_light.hpp
@@ -79,14 +79,8 @@ namespace sprout {
 						inter,
 						sprout::darkroom::objects::intersect(
 							objs,
-							sprout::darkroom::rays::make_ray(
-								sprout::darkroom::coords::add(
-									sprout::darkroom::coords::scale(
-										dir_,
-										sprout::numeric_limits<unit_type>::epsilon() * 256
-										),
-									sprout::darkroom::intersects::point_of_intersection(inter)
-									),
+							sprout::darkroom::rays::make_detached_ray(
+								sprout::darkroom::intersects::point_of_intersection(inter),
 								dir_
 								)
 							)
diff --git a/sprout/darkroom/lights/point_light.hpp b/sprout/darkroom/lights/point_light.hpp
index e5c20474..e6991736 100644
--- a/sprout/darkroom/lights/point_light.hpp
+++ b/sprout/darkroom/lights/point_light.hpp
@@ -83,14 +83,8 @@ namespace sprout {
 						direction,
 						sprout::darkroom::objects::intersect(
 							objs,
-							sprout::darkroom::rays::make_ray(
-								sprout::darkroom::coords::add(
-									sprout::darkroom::coords::scale(
-										direction,
-										sprout::numeric_limits<unit_type>::epsilon() * 256
-										),
-									sprout::darkroom::intersects::point_of_intersection(inter)
-									),
+							sprout::darkroom::rays::make_detached_ray(
+								sprout::darkroom::intersects::point_of_intersection(inter),
 								direction
 								)
 							)
diff --git a/sprout/darkroom/objects/sphere.hpp b/sprout/darkroom/objects/sphere.hpp
index 5e3e18d1..c53ac245 100644
--- a/sprout/darkroom/objects/sphere.hpp
+++ b/sprout/darkroom/objects/sphere.hpp
@@ -110,12 +110,15 @@ namespace sprout {
 				}
 				template<typename Ray, typename Vec>
 				SPROUT_CONSTEXPR typename intersection<Ray>::type
-				intersect_6(Ray const& ray, zwo_type const& zwo, drei_type const& drei, Vec const& normal) const {
+				intersect_6(Ray const& ray, zwo_type const& zwo, drei_type const& drei,bool is_from_inside, Vec const& normal) const {
 					return typename intersection<Ray>::type(
 						sprout::tuples::get<zw::does_intersect>(zwo),
 						sprout::tuples::get<zw::distance>(zwo),
 						sprout::tuples::get<dr::point_of_intersection>(drei),
-						sprout::tuples::get<dr::normal>(drei),
+						is_from_inside
+							? sprout::darkroom::coords::negate(normal)
+							: normal
+							,
 						sprout::darkroom::materials::calculate_material(	// ! Spherical
 							mat_,
 							sprout::atan2(
@@ -133,7 +136,7 @@ namespace sprout {
 								)
 								/ sprout::math::half_pi<unit_type>()
 							),
-						sprout::darkroom::coords::dot(normal, sprout::darkroom::rays::direction(ray)) > 0
+						is_from_inside
 						);
 				}
 				template<typename Ray>
@@ -143,6 +146,7 @@ namespace sprout {
 						ray,
 						zwo,
 						drei,
+						sprout::darkroom::coords::dot(sprout::tuples::get<dr::normal>(drei), sprout::darkroom::rays::direction(ray)) > 0,
 						sprout::tuples::get<dr::normal>(drei)
 						);
 				}
diff --git a/sprout/darkroom/rays/ray.hpp b/sprout/darkroom/rays/ray.hpp
index 01e27802..1bd233c4 100644
--- a/sprout/darkroom/rays/ray.hpp
+++ b/sprout/darkroom/rays/ray.hpp
@@ -9,6 +9,7 @@
 #define SPROUT_DARKROOM_RAYS_RAY_HPP
 
 #include <sprout/config.hpp>
+#include <sprout/limits.hpp>
 #include <sprout/tuple/tuple.hpp>
 #include <sprout/utility/forward.hpp>
 #include <sprout/darkroom/access/access.hpp>
@@ -63,6 +64,32 @@ namespace sprout {
 					sprout::darkroom::coords::scale(sprout::darkroom::rays::direction(ray), dist)
 					);
 			}
+
+			//
+			// detach_position
+			//
+			template<typename Position, typename Direction>
+			inline SPROUT_CONSTEXPR Position
+			detach_position(Position const& pos, Direction const& dir) {
+				return sprout::darkroom::coords::add(
+					pos,
+					sprout::darkroom::coords::resize(
+						dir,
+						sprout::numeric_limits<typename sprout::darkroom::access::unit<Direction>::type>::epsilon() * 256
+						)
+					);
+			}
+			//
+			// make_detached_ray
+			//
+			template<typename Position, typename Direction>
+			inline SPROUT_CONSTEXPR sprout::tuples::tuple<Position, Direction>
+			make_detached_ray(Position const& pos, Direction const& dir) {
+				return sprout::darkroom::rays::make_ray(
+					sprout::darkroom::rays::detach_position(pos, dir),
+					dir
+					);
+			}
 		}	// namespace rays
 	}	// namespace darkroom
 }	// namespace sprout
diff --git a/sprout/darkroom/renderers/whitted_style.hpp b/sprout/darkroom/renderers/whitted_style.hpp
index bd486246..937dd922 100644
--- a/sprout/darkroom/renderers/whitted_style.hpp
+++ b/sprout/darkroom/renderers/whitted_style.hpp
@@ -43,7 +43,7 @@ namespace sprout {
 					Camera const& camera, Objects const& objs, Lights const& lights,
 					Ray const& ray, Intersection const& inter, Renderer const& renderer,
 					std::size_t depth_max,
-					Direction const& reflect_dir
+					Direction const& new_dir
 					) const
 				{
 					return sprout::darkroom::renderers::calculate<Color>(
@@ -51,19 +51,8 @@ namespace sprout {
 						camera, objs, lights,
 						sprout::tuples::remake<Ray>(
 							ray,
-							sprout::darkroom::coords::add(
-								sprout::darkroom::intersects::point_of_intersection(inter),
-								sprout::darkroom::coords::scale(
-									reflect_dir,
-									sprout::numeric_limits<typename sprout::darkroom::access::unit<Direction>::type>::epsilon() * 256
-									)
-								// ???
-//								sprout::darkroom::coords::scale(
-//									sprout::darkroom::intersects::normal(inter),
-//									sprout::numeric_limits<typename sprout::darkroom::access::unit<Direction>::type>::epsilon() * 256
-//									)
-								),
-							reflect_dir
+							sprout::darkroom::rays::detach_position(sprout::darkroom::intersects::point_of_intersection(inter), new_dir),
+							new_dir
 							),
 						depth_max - 1
 						);
@@ -102,6 +91,80 @@ namespace sprout {
 				}
 			};
 			//
+			// whitted_transparent
+			//
+			class whitted_transparent {
+			private:
+				template<
+					typename Color,
+					typename Camera, typename Objects, typename Lights,
+					typename Ray, typename Intersection, typename Renderer,
+					typename Direction
+				>
+				SPROUT_CONSTEXPR Color
+				color_1(
+					Camera const& camera, Objects const& objs, Lights const& lights,
+					Ray const& ray, Intersection const& inter, Renderer const& renderer,
+					std::size_t depth_max,
+					Direction const& new_dir
+					) const
+				{
+					return !sprout::darkroom::coords::is_zero(new_dir)
+						? sprout::darkroom::renderers::calculate<Color>(
+							renderer,
+							camera, objs, lights,
+							sprout::tuples::remake<Ray>(
+								ray,
+								sprout::darkroom::rays::detach_position(sprout::darkroom::intersects::point_of_intersection(inter), new_dir),
+								new_dir
+								),
+							depth_max - 1
+							)
+						: sprout::tuples::make<Color>(0, 0, 0)
+						;
+				}
+			public:
+				template<
+					typename Color,
+					typename Camera, typename Objects, typename Lights,
+					typename Ray, typename Intersection, typename Renderer
+				>
+				SPROUT_CONSTEXPR Color
+				operator()(
+					Camera const& camera, Objects const& objs, Lights const& lights,
+					Ray const& ray, Intersection const& inter, Renderer const& renderer,
+					std::size_t depth_max
+					) const
+				{
+					typedef typename std::decay<
+						decltype(sprout::darkroom::materials::alpha(sprout::darkroom::intersects::material(inter)))
+					>::type alpha_type;
+					typedef typename std::decay<
+						decltype(sprout::darkroom::materials::refraction(sprout::darkroom::intersects::material(inter)))
+					>::type refraction_type;
+					return depth_max > 0
+						&& sprout::darkroom::intersects::does_intersect(inter)
+						&& sprout::darkroom::materials::alpha(sprout::darkroom::intersects::material(inter))
+							> sprout::numeric_limits<alpha_type>::epsilon()
+						&& sprout::darkroom::materials::refraction(sprout::darkroom::intersects::material(inter))
+							> sprout::numeric_limits<refraction_type>::epsilon()
+						? color_1<Color>(
+							camera, objs, lights,
+							ray, inter, renderer,
+							depth_max,
+							sprout::darkroom::coords::refract(
+								sprout::darkroom::rays::direction(ray),
+								sprout::darkroom::intersects::normal(inter),
+								sprout::darkroom::intersects::is_from_inside(inter)
+									? 1 / sprout::darkroom::materials::refraction(sprout::darkroom::intersects::material(inter))
+									: sprout::darkroom::materials::refraction(sprout::darkroom::intersects::material(inter))
+								)
+							)
+						: sprout::tuples::make<Color>(0, 0, 0)
+						;
+				}
+			};
+			//
 			// whitted_style
 			//
 			template<typename InfinityColor = sprout::darkroom::renderers::direction_gradation>
@@ -115,18 +178,24 @@ namespace sprout {
 				SPROUT_CONSTEXPR Color
 				color_3(
 					Ray const& ray, Intersection const& inter,
-					Color const& diffuse_color, Color const& mirror_color
+					Color const& diffuse_color, Color const& mirror_color, Color const& transparent_color
 					) const
 				{
 					return sprout::darkroom::intersects::does_intersect(inter)
 						? sprout::darkroom::colors::add(
 							sprout::darkroom::colors::mul(
 								diffuse_color,
-								1 - sprout::darkroom::materials::reflection(sprout::darkroom::intersects::material(inter))
+								1
+									- sprout::darkroom::materials::reflection(sprout::darkroom::intersects::material(inter))
+									- sprout::darkroom::materials::alpha(sprout::darkroom::intersects::material(inter))
 								),
 							sprout::darkroom::colors::mul(
 								mirror_color,
 								sprout::darkroom::materials::reflection(sprout::darkroom::intersects::material(inter))
+								),
+							sprout::darkroom::colors::mul(
+								transparent_color,
+								sprout::darkroom::materials::alpha(sprout::darkroom::intersects::material(inter))
 								)
 							)
 						: sprout::darkroom::renderers::calculate_infinity<Color>(infinity_color_, sprout::darkroom::rays::direction(ray))
@@ -148,6 +217,11 @@ namespace sprout {
 						ray, inter,
 						diffuse_color,
 						sprout::darkroom::renderers::whitted_mirror().template operator()<Color>(
+							camera, objs, lights,
+							ray, inter, *this,
+							depth_max
+							),
+						sprout::darkroom::renderers::whitted_transparent().template operator()<Color>(
 							camera, objs, lights,
 							ray, inter, *this,
 							depth_max