diff --git a/Graphics/Rendering/Ombra/Blend.hs b/Graphics/Rendering/Ombra/Blend.hs
--- a/Graphics/Rendering/Ombra/Blend.hs
+++ b/Graphics/Rendering/Ombra/Blend.hs
@@ -1,66 +1,12 @@
-module Graphics.Rendering.Ombra.Blend where
-
-import Data.Vect.Float (Vec4(..))
-import Data.Vect.Float.Instances ()
-import Graphics.Rendering.Ombra.Internal.GL
-
--- | Blend mode
-data Mode = Mode {
-        constantColor :: Maybe Vec4,
-        rgbOperator :: Operator,
-        rgbParameters :: Maybe (Parameter, Parameter),
-        alphaOperator :: Operator,
-        alphaParameters :: Maybe (Parameter, Parameter)
-} deriving Eq
-
--- | Blend operator.
-data Operator = Add | Subtract | ReverseSubtract {- Min | Max -} deriving Eq
-
--- | Blend function parameters.
-data Parameter = Zero | One | SourceColor | DestinationColor | ConstantColor
-               | SourceAlpha | DestinationAlpha | ConstantAlpha
-               | OneMinus Parameter deriving Eq
-
--- | Standard transparency (default).
-transparency :: Mode
-transparency = Mode Nothing Add (Just (SourceAlpha, OneMinus SourceAlpha))
-                            Add (Just (SourceAlpha, OneMinus SourceAlpha))
-
--- | Additive blend mode.
-additive :: Mode
-additive = Mode Nothing Add (Just (One, One)) Add (Just (One, One))
+module Graphics.Rendering.Ombra.Blend (
+        -- * Types
+        Mode(..),
+        Operator(..),
+        Parameter(..),
 
-equation :: GLES => Mode -> (GLEnum, GLEnum)
-equation m = (mode $ rgbOperator m, mode $ alphaOperator m)
-        where mode Add = gl_FUNC_ADD
-              mode Subtract = gl_FUNC_SUBTRACT
-              mode ReverseSubtract = gl_FUNC_REVERSE_SUBTRACT
-              -- mode Min = gl_MIN
-              -- mode Max = gl_MAX
+        -- * Blending modes
+        transparency,
+        additive
+) where
 
-function :: GLES => Mode -> (GLEnum, GLEnum, GLEnum, GLEnum)
-function m = (rgbs, rgbd, alphas, alphad)
-        where (rgbs, rgbd) = case rgbParameters m of
-                                  Just (p, p') -> (param p, param p')
-                                  Nothing -> (gl_ZERO, gl_ZERO)
-              (alphas, alphad) = case alphaParameters m of
-                                      Just (p, p') -> (param p, param p')
-                                      Nothing -> (gl_ZERO, gl_ZERO)
-              param Zero = gl_ZERO
-              param One = gl_ONE
-              param SourceColor = gl_SRC_COLOR
-              param DestinationColor = gl_DST_COLOR
-              param ConstantColor = gl_CONSTANT_COLOR
-              param SourceAlpha = gl_SRC_ALPHA
-              param DestinationAlpha = gl_DST_ALPHA
-              param ConstantAlpha = gl_CONSTANT_ALPHA
-              param (OneMinus Zero) = gl_ONE
-              param (OneMinus One) = gl_ZERO
-              param (OneMinus SourceColor) = gl_ONE_MINUS_SRC_COLOR
-              param (OneMinus DestinationColor) = gl_ONE_MINUS_DST_COLOR
-              param (OneMinus ConstantColor) = gl_ONE_MINUS_CONSTANT_COLOR
-              param (OneMinus SourceAlpha) = gl_ONE_MINUS_SRC_ALPHA
-              param (OneMinus DestinationAlpha) = gl_ONE_MINUS_DST_ALPHA
-              param (OneMinus ConstantAlpha) = gl_ONE_MINUS_CONSTANT_ALPHA
-              param (OneMinus _) =
-                      error "Invalid blend function (nested OneMinus)"
+import Graphics.Rendering.Ombra.Blend.Internal
diff --git a/Graphics/Rendering/Ombra/Blend/Internal.hs b/Graphics/Rendering/Ombra/Blend/Internal.hs
new file mode 100644
--- /dev/null
+++ b/Graphics/Rendering/Ombra/Blend/Internal.hs
@@ -0,0 +1,66 @@
+module Graphics.Rendering.Ombra.Blend.Internal where
+
+import Data.Vect.Float (Vec4(..))
+import Data.Vect.Float.Instances ()
+import Graphics.Rendering.Ombra.Internal.GL
+
+-- | Blend mode
+data Mode = Mode {
+        constantColor :: Maybe Vec4,
+        rgbOperator :: Operator,
+        rgbParameters :: Maybe (Parameter, Parameter),
+        alphaOperator :: Operator,
+        alphaParameters :: Maybe (Parameter, Parameter)
+} deriving Eq
+
+-- | Blend operator.
+data Operator = Add | Subtract | ReverseSubtract {- Min | Max -} deriving Eq
+
+-- | Blend function parameters.
+data Parameter = Zero | One | SourceColor | DestinationColor | ConstantColor
+               | SourceAlpha | DestinationAlpha | ConstantAlpha
+               | OneMinus Parameter deriving Eq
+
+-- | Standard transparency (default).
+transparency :: Mode
+transparency = Mode Nothing Add (Just (SourceAlpha, OneMinus SourceAlpha))
+                            Add (Just (SourceAlpha, OneMinus SourceAlpha))
+
+-- | Additive blend mode.
+additive :: Mode
+additive = Mode Nothing Add (Just (One, One)) Add (Just (One, One))
+
+equation :: GLES => Mode -> (GLEnum, GLEnum)
+equation m = (mode $ rgbOperator m, mode $ alphaOperator m)
+        where mode Add = gl_FUNC_ADD
+              mode Subtract = gl_FUNC_SUBTRACT
+              mode ReverseSubtract = gl_FUNC_REVERSE_SUBTRACT
+              -- mode Min = gl_MIN
+              -- mode Max = gl_MAX
+
+function :: GLES => Mode -> (GLEnum, GLEnum, GLEnum, GLEnum)
+function m = (rgbs, rgbd, alphas, alphad)
+        where (rgbs, rgbd) = case rgbParameters m of
+                                  Just (p, p') -> (param p, param p')
+                                  Nothing -> (gl_ZERO, gl_ZERO)
+              (alphas, alphad) = case alphaParameters m of
+                                      Just (p, p') -> (param p, param p')
+                                      Nothing -> (gl_ZERO, gl_ZERO)
+              param Zero = gl_ZERO
+              param One = gl_ONE
+              param SourceColor = gl_SRC_COLOR
+              param DestinationColor = gl_DST_COLOR
+              param ConstantColor = gl_CONSTANT_COLOR
+              param SourceAlpha = gl_SRC_ALPHA
+              param DestinationAlpha = gl_DST_ALPHA
+              param ConstantAlpha = gl_CONSTANT_ALPHA
+              param (OneMinus Zero) = gl_ONE
+              param (OneMinus One) = gl_ZERO
+              param (OneMinus SourceColor) = gl_ONE_MINUS_SRC_COLOR
+              param (OneMinus DestinationColor) = gl_ONE_MINUS_DST_COLOR
+              param (OneMinus ConstantColor) = gl_ONE_MINUS_CONSTANT_COLOR
+              param (OneMinus SourceAlpha) = gl_ONE_MINUS_SRC_ALPHA
+              param (OneMinus DestinationAlpha) = gl_ONE_MINUS_DST_ALPHA
+              param (OneMinus ConstantAlpha) = gl_ONE_MINUS_CONSTANT_ALPHA
+              param (OneMinus _) =
+                      error "Invalid blend function (nested OneMinus)"
diff --git a/Graphics/Rendering/Ombra/D2.hs b/Graphics/Rendering/Ombra/D2.hs
--- a/Graphics/Rendering/Ombra/D2.hs
+++ b/Graphics/Rendering/Ombra/D2.hs
@@ -102,7 +102,7 @@
                :~> mconcat os
 
 -- | A 'Layer' with the standard 2D program.
-layerS :: IsObject2D gs is => Object gs is -> Layer
+layerS :: IsObject2D gs is => Object gs is -> Layer' s t ()
 layerS = layer defaultProgram2D
 
 -- | Translate a 2D 'Object'.
diff --git a/Graphics/Rendering/Ombra/D3.hs b/Graphics/Rendering/Ombra/D3.hs
--- a/Graphics/Rendering/Ombra/D3.hs
+++ b/Graphics/Rendering/Ombra/D3.hs
@@ -113,7 +113,7 @@
         where tupleToVec (w, h) = Vec2 (fromIntegral w) (fromIntegral h)
 
 -- | A 'Layer' with the standard 3D program.
-layerS :: IsObject3D gs is => Object gs is -> Layer
+layerS :: IsObject3D gs is => Object gs is -> Layer' s t ()
 layerS = layer defaultProgram3D
 
 -- | Translate a 3D Object.
diff --git a/Graphics/Rendering/Ombra/Draw/Internal.hs b/Graphics/Rendering/Ombra/Draw/Internal.hs
--- a/Graphics/Rendering/Ombra/Draw/Internal.hs
+++ b/Graphics/Rendering/Ombra/Draw/Internal.hs
@@ -23,15 +23,13 @@
         execDraw,
         evalDraw,
         gl,
-        renderLayer,
-        layerToTexture,
         drawGet
 ) where
 
-import qualified Graphics.Rendering.Ombra.Blend as Blend
+import qualified Graphics.Rendering.Ombra.Blend.Internal as Blend
 import Graphics.Rendering.Ombra.Color
 import Graphics.Rendering.Ombra.Geometry.Internal
-import Graphics.Rendering.Ombra.Layer.Internal
+import Graphics.Rendering.Ombra.Layer.Internal hiding (clear)
 import Graphics.Rendering.Ombra.Object.Internal
 import Graphics.Rendering.Ombra.Texture.Internal
 import Graphics.Rendering.Ombra.Backend (GLES)
@@ -45,7 +43,7 @@
 import Graphics.Rendering.Ombra.Shader.GLSL
 import Graphics.Rendering.Ombra.Shader.Program
 import Graphics.Rendering.Ombra.Shader.ShaderVar
-import qualified Graphics.Rendering.Ombra.Stencil as Stencil
+import qualified Graphics.Rendering.Ombra.Stencil.Internal as Stencil
 
 import Data.Hashable (Hashable)
 import Data.Vect.Float
@@ -193,15 +191,49 @@
 removeProgram = removeDrawResource gl programs
 
 -- | Draw a 'Layer'.
-drawLayer :: GLES => Layer -> Draw ()
-drawLayer (Layer prg grp) = setProgram prg >> drawObject grp
-drawLayer (SubLayer rl) =
-        do (layer, textures) <- renderLayer rl
-           drawLayer layer
-           mapM_ removeTexture textures
-drawLayer (OverLayer top behind) = drawLayer behind >> drawLayer top
-drawLayer (ClearLayer bufs l) = clearBuffers bufs >> drawLayer l
+drawLayer :: GLES => Layer' Drawable t a -> Draw a
+drawLayer = fmap fst . flip drawLayer' []
 
+drawLayer' :: GLES
+           => Layer' s t a
+           -> [TTexture t]
+           -> Draw (a, [TTexture t])
+drawLayer' (Layer prg grp) ts = do setProgram prg
+                                   drawObject grp
+                                   return ((), ts)
+drawLayer' (TextureLayer drawBufs stypes (w, h) (rx, ry, rw, rh)
+                         inspCol inspDepth layer) tts0 =
+        do (x, tts1, ts, mcol, mdepth) <-
+                layerToTexture drawBufs stypes w h layer
+                               (mayInspect inspCol) (mayInspect inspDepth) tts0
+           let tts2 = map (TTexture . LoadedTexture gw gh) ts
+           return ((x, tts2, mcol, mdepth), tts1 ++ tts2)
+        where (gw, gh) = (fromIntegral w, fromIntegral h)
+        
+              mayInspect :: Bool
+                         -> Either (Maybe [r])
+                                   ([r] -> Draw (Maybe [r]), Int, Int, Int, Int)
+              mayInspect True = Right (return . Just, rx, ry, rw, rh)
+              mayInspect False = Left Nothing
+drawLayer' (Permanent tt@(TTexture lt)) tts = 
+        do let t = TextureLoaded lt
+           gl $ unloader t (Nothing :: Maybe TextureImage) lt
+           return (t, filter (/= tt) tts)
+drawLayer' (WithTTextures ets f) tts =
+        do drawLayer . f $ map (\(TTexture lt) -> TextureLoaded lt) ets
+           return ((), tts)
+drawLayer' (Free layer) tts =
+        do (x, tts') <- drawLayer' layer []
+           mapM_ (\(TTexture lt) -> removeTexture $ TextureLoaded lt) tts'
+           return (x, tts)
+drawLayer' (Clear bufs) tts = clearBuffers bufs >> return ((), tts)
+drawLayer' (Cast layer) tts =
+        do (x, tts') <- drawLayer' layer $ map castTTexture tts
+           return (x, map castTTexture tts')
+drawLayer' (Bind lx f) tts0 = drawLayer' lx tts0 >>=
+                                \(x, tts1) -> drawLayer' (f x) tts1
+drawLayer' (Return x) tts = return (x, tts)
+
 -- | Draw an 'Object'.
 drawObject :: GLES => Object gs is -> Draw ()
 drawObject (g :~> o) = withGlobal g $ drawObject o
@@ -305,28 +337,13 @@
 getProgram :: GLES => Program gs is -> Draw (Either String LoadedProgram)
 getProgram = getDrawResource gl programs
 
--- | Realize a 'RenderLayer'. It returns the list of allocated 'Texture's so
--- that you can free them if you want.
-renderLayer :: GLES => RenderLayer a -> Draw (a, [Texture])
-renderLayer (RenderLayer drawBufs stypes w h rx ry rw rh
-                         inspCol inspDepth layer f) =
-        do (ts, mcol, mdepth) <- layerToTexture drawBufs stypes w h layer
-                                                (mayInspect inspCol)
-                                                (mayInspect inspDepth)
-           return (f ts mcol mdepth, ts)
-        where mayInspect :: Bool
-                         -> Either (Maybe [r])
-                                   ([r] -> Draw (Maybe [r]), Int, Int, Int, Int)
-              mayInspect True = Right (return . Just, rx, ry, rw, rh)
-              mayInspect False = Left Nothing
-
 -- | Draw a 'Layer' on some textures.
 layerToTexture :: (GLES, Integral a)
                => Bool                                  -- ^ Draw buffers
                -> [LayerType]                           -- ^ Textures contents
                -> a                                     -- ^ Width
                -> a                                     -- ^ Height
-               -> Layer                                 -- ^ Layer to draw
+               -> Layer' s t x                          -- ^ Layer to draw
                -> Either b ( [Color] -> Draw b
                            , Int, Int, Int, Int)        -- ^ Color inspecting
                                                         -- function, start x,
@@ -335,16 +352,17 @@
                -> Either c ( [Word8] -> Draw c
                            , Int, Int, Int, Int)        -- ^ Depth inspecting,
                                                         -- function, etc.
-               -> Draw ([Texture], b ,c)
-layerToTexture drawBufs stypes wp hp layer einspc einspd = do
-        (ts, (colRes, depthRes)) <- renderToTexture drawBufs (map arguments
-                                                    stypes) w h $
-                        do drawLayer layer
+               -> [TTexture t]
+               -> Draw (x, [TTexture t], [GL.Texture], b ,c)
+layerToTexture drawBufs stypes wp hp layer einspc einspd tts = do
+        (ts, (x, tts', colRes, depthRes)) <-
+                renderToTexture drawBufs (map arguments stypes) w h $
+                        do (x, tts') <- drawLayer' layer tts
                            colRes <- inspect einspc gl_RGBA wordsToColors 4
                            depthRes <- inspect einspd gl_DEPTH_COMPONENT id 1
-                           return (colRes, depthRes)
+                           return (x, tts', colRes, depthRes)
 
-        return (map (TextureLoaded . LoadedTexture w h) ts, colRes, depthRes)
+        return (x, tts', ts, colRes, depthRes)
 
         where (w, h) = (fromIntegral wp, fromIntegral hp)
               arguments stype =
diff --git a/Graphics/Rendering/Ombra/Internal/Resource.hs b/Graphics/Rendering/Ombra/Internal/Resource.hs
--- a/Graphics/Rendering/Ombra/Internal/Resource.hs
+++ b/Graphics/Rendering/Ombra/Internal/Resource.hs
@@ -9,7 +9,8 @@
         newResMap,
         addResource,
         getResource,
-        removeResource
+        removeResource,
+        unloader
 ) where
 
 import Control.Monad.IO.Class
@@ -88,3 +89,6 @@
                 Loaded r -> unloadResource mi r
                 _ -> return ()
            liftIO $ H.delete map i
+
+unloader :: (Resource i r m, EmbedIO m) => k -> Maybe i -> r -> m ()
+unloader k i r = embedIO (addFinalizer k) $ unloadResource i r
diff --git a/Graphics/Rendering/Ombra/Layer.hs b/Graphics/Rendering/Ombra/Layer.hs
--- a/Graphics/Rendering/Ombra/Layer.hs
+++ b/Graphics/Rendering/Ombra/Layer.hs
@@ -21,6 +21,26 @@
         buffersSubLayer,
         buffersDepthSubLayer,
         buffersStencilSubLayer,
+        -- * Layers with return values
+        -- $extlayers
+        Layer',
+        LayerStatus(..),
+        drawable,
+        castLayer,
+        -- ** Temporary textures
+        TTexture,
+        withTTexture,
+        permanent,
+        -- ** Drawing to textures
+        depthToTexture,
+        colorDepthToTexture,
+        colorStencilToTexture,
+        colorToTexture',
+        depthToTexture',
+        colorDepthToTexture',
+        colorStencilToTexture',
+        buffersDepthToTexture,
+        buffersStencilToTexture
 ) where
 
 import Data.Word (Word8)
@@ -34,7 +54,7 @@
 
 -- | Create a simple Layer from a Program and an Object.
 layer :: (Subset progAttr grpAttr, Subset progUni grpUni)
-      => Program progUni progAttr -> Object grpUni grpAttr -> Layer
+      => Program progUni progAttr -> Object grpUni grpAttr -> Layer' s t ()
 layer = Layer
 
 infixl 1 `over`
@@ -42,16 +62,7 @@
 -- will use the same buffers (color, depth, stencil) of the second, but
 -- the visibility of the objects still depends on their depth.
 over :: Layer -> Layer -> Layer
-over = OverLayer
-
--- TODO: document buffers.
--- | Clear some buffers before drawing a Layer.
-clear :: [Buffer] -> Layer -> Layer
-clear = ClearLayer
-
--- | Generate a 1x1 texture.
-colorTex :: GLES => Color -> Texture
-colorTex c = mkTexture 1 1 [ c ]
+over = flip (>>)
 
 -- | Alias for 'colorSubLayer'.
 subLayer :: Int -> Int -> Layer -> (Texture -> Layer) -> Layer
@@ -63,7 +74,7 @@
               -> Layer                  -- ^ Layer to draw on a 'Texture'.
               -> (Texture -> Layer)     -- ^ Layers using the texture.
               -> Layer
-colorSubLayer w h l = subRenderLayer . renderColor w h l
+colorSubLayer w h l = colorDepthSubLayer w h l . flip . const
 
 -- | Use a 'Layer' as a depth 'Texture' on another.
 depthSubLayer :: Int                         -- ^ Texture width.
@@ -72,7 +83,8 @@
                                              -- depth 'Texture'.
               -> (Texture -> Layer)          -- ^ Layers using the texture.
               -> Layer
-depthSubLayer w h l = subRenderLayer . renderDepth w h l
+depthSubLayer w h l f = drawable $
+        depthToTexture w h (castLayer l) >>= \(_, t) -> withTTexture t f
 
 -- | Combination of 'colorSubLayer' and 'depthSubLayer'.
 colorDepthSubLayer :: Int                               -- ^ Texture width.
@@ -81,7 +93,10 @@
                                                         -- 'Texture's.
                    -> (Texture -> Texture -> Layer)     -- ^ Color, depth.
                    -> Layer
-colorDepthSubLayer w h l = subRenderLayer . renderColorDepth w h l
+colorDepthSubLayer w h l f = drawable $
+        colorDepthToTexture w h (castLayer l) >>=
+                \(_, ct, dt) -> withTTextures [ct, dt] $
+                        \[ct', dt'] -> f ct' dt'
 
 -- | 'colorSubLayer' with a stencil buffer.
 colorStencilSubLayer :: Int                     -- ^ Texture width.
@@ -89,68 +104,74 @@
                      -> Layer                   -- ^ Layer to draw on a 'Texture'
                      -> (Texture -> Layer)      -- ^ Color.
                      -> Layer
-colorStencilSubLayer w h l = subRenderLayer . renderColorStencil w h l
+colorStencilSubLayer w h l f = drawable $
+        colorStencilToTexture w h (castLayer l) >>= \(_, t) -> withTTexture t f
 
 -- | Extended version of 'colorSubLayer' that reads and converts the Texture
 -- pixels.
 colorSubLayer'
         :: Int                          -- ^ Texture width.
         -> Int                          -- ^ Texture height.
-        -> Layer                        -- ^ Layer to draw on a 'Texture'.
         -> Int                          -- ^ First pixel to read X
         -> Int                          -- ^ First pixel to read Y
         -> Int                          -- ^ Width of the rectangle to read
         -> Int                          -- ^ Height of the rectangle to read
+        -> Layer                        -- ^ Layer to draw on a 'Texture'.
         -> (Texture -> [Color] -> Layer) -- ^ Function using the texture.
         -> Layer
-colorSubLayer' w h l rx ry rw rh =
-        subRenderLayer . renderColorInspect w h l rx ry rw rh
+colorSubLayer' w h rx ry rw rh l f = drawable $
+        colorToTexture' w h rx ry rw rh (castLayer l) >>=
+                \(_, t, c) -> withTTexture t $ flip f c
 
 -- | Extended version of 'depthSubLayer'. Not supported on WebGL.
 depthSubLayer'
         :: Int                          -- ^ Texture width.
         -> Int                          -- ^ Texture height.
-        -> Layer                        -- ^ Layer to draw on a depth 'Texture'.
         -> Int                          -- ^ First pixel to read X
         -> Int                          -- ^ First pixel to read Y
         -> Int                          -- ^ Width of the rectangle to read
         -> Int                          -- ^ Height of the rectangle to read
+        -> Layer                        -- ^ Layer to draw on a depth 'Texture'.
         -> (Texture -> [Word8] -> Layer) -- ^ Layers using the texture.
         -> Layer
-depthSubLayer' w h l rx ry rw rh =
-        subRenderLayer . renderDepthInspect w h l rx ry rw rh
+depthSubLayer' w h rx ry rw rh l f = drawable $
+        depthToTexture' w h rx ry rw rh (castLayer l) >>=
+                \(_, t, d) -> withTTexture t $ flip f d
 
 -- | Extended version of 'colorDepthSubLayer'. Not supported on WebGL.
 colorDepthSubLayer'
         :: Int         -- ^ Texture width.
         -> Int         -- ^ Texture height.
-        -> Layer       -- ^ Layer to draw on a 'Texture'
         -> Int         -- ^ First pixel to read X
         -> Int         -- ^ First pixel to read Y
         -> Int         -- ^ Width of the rectangle to read
         -> Int         -- ^ Height of the rectangle to read
+        -> Layer       -- ^ Layer to draw on a 'Texture'
         -> (Texture -> Texture -> [Color] -> [Word8] -> Layer) -- ^ Layers using
                                                                -- the texture.
         -> Layer
-colorDepthSubLayer' w h l rx ry rw rh =
-        subRenderLayer . renderColorDepthInspect w h l rx ry rw rh
+colorDepthSubLayer' w h rx ry rw rh l f = drawable $
+        colorDepthToTexture' w h rx ry rw rh (castLayer l) >>=
+                \(_, ct, dt, c, d) -> withTTextures [ct, dt] $
+                        \[ct', dt'] -> f ct' dt' c d
 
 -- | 'colorSubLayer'' with an additional stencil buffer.
 colorStencilSubLayer'
         :: Int                          -- ^ Texture width.
         -> Int                          -- ^ Texture height.
-        -> Layer                        -- ^ Layer to draw on a 'Texture'.
         -> Int                          -- ^ First pixel to read X
         -> Int                          -- ^ First pixel to read Y
         -> Int                          -- ^ Width of the rectangle to read
         -> Int                          -- ^ Height of the rectangle to read
+        -> Layer                        -- ^ Layer to draw on a 'Texture'.
         -> (Texture -> [Color] -> Layer) -- ^ Function using the texture.
         -> Layer
-colorStencilSubLayer' w h l rx ry rw rh =
-        subRenderLayer . renderColorStencilInspect w h l rx ry rw rh
+colorStencilSubLayer' w h rx ry rw rh l f = drawable $
+        colorStencilToTexture' w h rx ry rw rh (castLayer l) >>=
+                \(_, t, c) -> withTTexture t $ flip f c
 
--- | Render a 'Layer' with multiple floating point colors
--- (use 'Fragment2', 'Fragment3', etc.) in some 'Texture's and use them to
+-- | Draw a 'Layer' with multiple floating point colors
+-- (use 'Fragment2', 'Fragment3', etc.) to some 'Texture's and use them to
 -- create another Layer.
 buffersSubLayer :: Int                          -- ^ Textures width.
                 -> Int                          -- ^ Textures height.
@@ -158,7 +179,7 @@
                 -> Layer                        -- ^ Layer to draw.
                 -> ([Texture] -> Layer)         -- ^ Function using the textures.
                 -> Layer
-buffersSubLayer w h n l = subRenderLayer . renderBuffers w h n l
+buffersSubLayer w h n l = buffersDepthSubLayer w h n l . flip . const
 
 -- | Combination of 'buffersSubLayer' and 'depthSubLayer'.
 buffersDepthSubLayer :: Int                             -- ^ Textures width.
@@ -169,7 +190,10 @@
                                                         -- buffers textures and
                                                         -- the depth texture.
                    -> Layer
-buffersDepthSubLayer w h n l = subRenderLayer . renderBuffersDepth w h n l
+buffersDepthSubLayer w h n l f = drawable $
+        buffersDepthToTexture w h n (castLayer l) >>=
+                \(_, bts, dt) -> withTTextures (dt : bts) $
+                        \(dt' : bts') -> f bts' dt'
 
 -- | 'buffersSubLayer' with an additional stencil buffer.
 buffersStencilSubLayer :: Int                   -- ^ Textures width.
@@ -178,129 +202,12 @@
                        -> Layer                 -- ^ Layer to draw.
                        -> ([Texture] -> Layer)  -- ^ Function using the texture.
                        -> Layer
-buffersStencilSubLayer w h n l = subRenderLayer . renderBuffersStencil w h n l
-
-subRenderLayer :: RenderLayer Layer -> Layer
-subRenderLayer = SubLayer
-
--- | Render a 'Layer' in a 'Texture'.
-renderColor :: Int -> Int -> Layer -> (Texture -> a) -> RenderLayer a
-renderColor w h l f = RenderLayer False [ColorLayer, DepthLayer] w h 0 0 0 0
-                                  False False l $ \[t, _] _ _ -> f t
-
--- | Render a 'Layer' in a depth 'Texture'.
-renderDepth :: Int -> Int -> Layer -> (Texture -> a) -> RenderLayer a
-renderDepth w h l f =
-        RenderLayer False [DepthLayer] w h 0 0 0 0 False False l $
-                \[t] _ _ -> f t
-
--- | Combination of 'renderColor' and 'renderDepth'.
-renderColorDepth :: Int
-                 -> Int
-                 -> Layer
-                 -> (Texture -> Texture -> a)
-                 -> RenderLayer a
-renderColorDepth w h l f =
-        RenderLayer False [ColorLayer, DepthLayer] w h 0 0 0 0 False False l $
-                    \[ct, dt] _ _ -> f ct dt
-
--- | 'renderColor' with an additional stencil buffer.
-renderColorStencil :: Int
-                   -> Int
-                   -> Layer
-                   -> (Texture -> a)
-                   -> RenderLayer a
-renderColorStencil w h l f =
-        RenderLayer False [ColorLayer, DepthStencilLayer] w h 0 0 0 0
-                    False False l $
-                    \[ct, _] _ _ -> f ct
-
--- | Render a 'Layer' in a 'Texture', reading the content of the texture.
-renderColorInspect :: Int
-                   -> Int
-                   -> Layer
-                   -> Int
-                   -> Int
-                   -> Int
-                   -> Int
-                   -> (Texture -> [Color] -> a)
-                   -> RenderLayer a
-renderColorInspect w h l rx ry rw rh f =
-        RenderLayer False [ColorLayer, DepthLayer] w h rx ry
-                    rw rh True False l $
-                    \[t, _] (Just c) _ -> f t c
-
--- | Render a 'Layer' in a depth 'Texture', reading the content of the texture.
--- Not supported on WebGL.
-renderDepthInspect :: Int
-                   -> Int
-                   -> Layer
-                   -> Int
-                   -> Int
-                   -> Int
-                   -> Int
-                   -> (Texture -> [Word8] -> a)
-                   -> RenderLayer a
-renderDepthInspect w h l rx ry rw rh f =
-        RenderLayer False [DepthLayer] w h rx ry rw rh False True l $
-                    \[t] _ (Just d) -> f t d
-
--- | Combination of 'renderColorInspect' and 'renderDepthInspect'. Not supported
--- on WebGL.
-renderColorDepthInspect :: Int
-                        -> Int
-                        -> Layer
-                        -> Int
-                        -> Int
-                        -> Int
-                        -> Int
-                        -> (Texture -> Texture -> [Color] -> [Word8] -> a)
-
-                        -> RenderLayer a
-renderColorDepthInspect w h l rx ry rw rh f =
-        RenderLayer False [ColorLayer, DepthLayer] w h rx ry rw rh True True l $
-                    \[ct, dt] (Just c) (Just d) -> f ct dt c d
-
--- | 'renderColorInspect' with an additional stencil buffer.
-renderColorStencilInspect :: Int
-                          -> Int
-                          -> Layer
-                          -> Int
-                          -> Int
-                          -> Int
-                          -> Int
-                          -> (Texture -> [Color] -> a)
-                          -> RenderLayer a
-renderColorStencilInspect w h l rx ry rw rh f =
-        RenderLayer False [ColorLayer, DepthStencilLayer] w h rx ry
-                    rw rh True False l $
-                    \[t, _] (Just c) _ -> f t c
-
--- | Render a 'Layer' with multiple floating point colors
--- (use 'Fragment2', 'Fragment3', etc.) in some 'Texture's.
-renderBuffers :: Int -> Int -> Int -> Layer -> ([Texture] -> a) -> RenderLayer a
-renderBuffers w h n l f =
-        RenderLayer True (DepthLayer : map BufferLayer [0 .. n - 1]) w h
-                    0 0 0 0 False False l $ \(_ : ts) _ _ -> f ts
-
--- | Combination of 'renderBuffers' and 'renderDepth'.
-renderBuffersDepth :: Int
-                   -> Int
-                   -> Int
-                   -> Layer
-                   -> ([Texture] -> Texture -> a)
-                   -> RenderLayer a
-renderBuffersDepth w h n l f =
-        RenderLayer True (DepthLayer : map BufferLayer [0 .. n - 1]) w h
-                    0 0 0 0 False False l $ \(dt : ts) _ _ -> f ts dt
+buffersStencilSubLayer w h n l f = drawable $
+        buffersStencilToTexture w h n (castLayer l) >>=
+                \(_, bts) -> withTTextures bts f
 
--- | 'renderBuffers' with an additional stencil buffer.
-renderBuffersStencil :: Int
-                     -> Int
-                     -> Int
-                     -> Layer
-                     -> ([Texture] -> a)
-                     -> RenderLayer a
-renderBuffersStencil w h n l f =
-        RenderLayer True (DepthStencilLayer : map BufferLayer [0 .. n - 1]) w h
-                    0 0 0 0 False False l $ \(_ : ts) _ _ -> f ts
+-- $extlayers
+-- Functions like 'subLayer' create temporary textures that usually have to be
+-- freed immediately after drawing the layer, otherwise they may waste a lot of
+-- GPU memory if @subLayer@ is called in every frame. The 'Layer'' type lets
+-- you extract those textures after having made permanent.
diff --git a/Graphics/Rendering/Ombra/Layer/Internal.hs b/Graphics/Rendering/Ombra/Layer/Internal.hs
--- a/Graphics/Rendering/Ombra/Layer/Internal.hs
+++ b/Graphics/Rendering/Ombra/Layer/Internal.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE ExistentialQuantification #-}
+{-# LANGUAGE GADTs, RankNTypes, DataKinds, KindSignatures #-}
 
 module Graphics.Rendering.Ombra.Layer.Internal where
 
@@ -7,29 +7,211 @@
 import Graphics.Rendering.Ombra.Internal.TList
 import Graphics.Rendering.Ombra.Object.Internal
 import Graphics.Rendering.Ombra.Shader.Program
-import Graphics.Rendering.Ombra.Texture
+import Graphics.Rendering.Ombra.Texture.Internal
 
 -- | An 'Object' associated with a program.
-data Layer = forall oi pi og pg. (Subset pi oi, Subset pg og)
-                              => Layer (Program pg pi) (Object og oi)
-           | SubLayer (RenderLayer Layer)
-           | OverLayer Layer Layer
-           | ClearLayer [Buffer] Layer
+type Layer = Layer' Drawable () ()
 
-data Buffer = ColorBuffer | DepthBuffer | StencilBuffer
+-- | A layer with a return value. It may also be 'NonDrawable', this means that
+-- there are some protected temporary resources and you have to call 'drawable'
+-- to turn it into a normal layer. The second parameter prevents the 'TTexture's
+-- from being returned by a @NonDrawable@ layer in a @drawable@ operation.
+--
+-- Note that layers are monads: @flip ('>>')@ is equivalent to 'over' for
+-- Drawable layers, while ('>>='), in combination with the *ToTexture functions,
+-- can be used to achieve the same effect of the subLayer functions.
+data Layer' (s :: LayerStatus) t a where
+        Layer :: (Subset pi oi, Subset pg og)
+              => Program pg pi
+              -> Object og oi
+              -> Layer' s t ()
+        TextureLayer :: Bool                    -- Use drawBuffers
+                     -> [LayerType]             -- Attachments
+                     -> (Int, Int)              -- Width, height
+                     -> (Int, Int, Int, Int)    -- Inspect rectangle
+                     -> Bool                    -- Inspect color
+                     -> Bool                    -- Inspect depth
+                     -> Layer' s t a            -- Layer to draw
+                     -> Layer' NonDrawable t
+                               (a, [TTexture t], Maybe [Color], Maybe [Word8])
+        Permanent :: TTexture t -> Layer' NonDrawable t Texture
+        WithTTextures :: [TTexture t]
+                      -> ([Texture] -> Layer)
+                      -> Layer' NonDrawable t ()
+        Free :: (forall t. Layer' NonDrawable t a) -> Layer' s t a
+        Clear :: [Buffer] -> Layer' s t ()
+        Cast :: Layer' Drawable t a -> Layer' Drawable t' a
+        Bind :: Layer' s t a -> (a -> Layer' s t b) -> Layer' s t b
+        Return :: a -> Layer' s t a
 
--- | Represents a 'Layer' drawn on a 'Texture'.
-data RenderLayer a = RenderLayer Bool                   -- Use drawBuffers
-                                 [LayerType]            -- Attachments
-                                 Int Int                -- Width, height
-                                 Int Int Int Int        -- Inspect rectangle
-                                 Bool Bool              -- Inspect color, depth
-                                 Layer                  -- Layer to draw
-                                 ([Texture] -> Maybe [Color] ->
-                                  Maybe [Word8] -> a)   -- Accepting function
+-- | Temporary texture.
+newtype TTexture t = TTexture LoadedTexture deriving Eq
 
+data LayerStatus = Drawable | NonDrawable
+
+data Buffer = ColorBuffer | DepthBuffer | StencilBuffer
+
 data LayerType = ColorLayer
                | DepthLayer
                | DepthStencilLayer
                | BufferLayer Int deriving Eq
 
+instance Functor (Layer' s t) where
+        fmap f = flip Bind $ Return . f
+
+instance Applicative (Layer' s t) where
+        lf <*> lx = Bind lf $ \f -> Bind lx $ \x -> Return $ f x
+        pure = Return
+
+instance Monad (Layer' s t) where
+        (>>=) = Bind
+        return = Return
+
+-- TODO: document buffers.
+-- | Clear some buffers before drawing a Layer.
+clear :: [Buffer] -> Layer' s t a -> Layer' s t a
+clear bs = (Clear bs >>)
+
+-- | Free the temporary resources associated with a NonDrawable layer, before
+-- drawing it.
+drawable :: (forall t. Layer' NonDrawable t a) -> Layer' s t a
+drawable = Free
+
+castDrawable :: Layer' Drawable t a -> Layer' Drawable t' a
+castDrawable = Cast
+
+-- | Make the type of a simple 'Layer' more generic.
+castLayer :: Layer -> Layer' Drawable t ()
+castLayer = castDrawable
+
+-- | Make a 'TTexture' permanent. Its lifetime is still bound to the 'Texture'
+-- returned.
+permanent :: TTexture t -> Layer' NonDrawable t Texture
+permanent = Permanent
+
+-- | Draw a Layer using a temporary texture.
+withTTexture :: TTexture t -> (Texture -> Layer) -> Layer' NonDrawable t ()
+withTTexture pt f = WithTTextures [pt] $ \[t] -> f t
+
+-- | Draw a Layer using a list of temporary textures.
+withTTextures :: [TTexture t] -> ([Texture] -> Layer) -> Layer' NonDrawable t ()
+withTTextures = WithTTextures
+
+castTTexture :: TTexture t -> TTexture t'
+castTTexture (TTexture lt) = TTexture lt
+
+-- | Draw a 'Layer' to a depth 'Texture'.
+depthToTexture :: Int           -- ^ Textures width.
+               -> Int           -- ^ Textures height.
+               -> Layer' s t a  -- ^ Layer to draw.
+               -> Layer' NonDrawable t (a, TTexture t)
+depthToTexture w h l =
+        fmap (\(x, [t], _, _) -> (x, t)) $
+                TextureLayer False [DepthLayer] (w, h) (0, 0, 0, 0)
+                             False False l
+
+-- | Draw a 'Layer' to a color 'Texture' and a depth 'Texture'.
+colorDepthToTexture :: Int              -- ^ Textures width.
+                    -> Int              -- ^ Textures height.
+                    -> Layer' s t a     -- ^ Layer to draw.
+                    -> Layer' NonDrawable t (a, TTexture t, TTexture t)
+colorDepthToTexture w h l =
+        fmap (\(x, [ct, dt], _, _) -> (x, ct, dt)) $
+                TextureLayer False [ColorLayer, DepthLayer] (w, h) (0, 0, 0, 0)
+                             False False l
+
+-- | Draw a 'Layer' to a color 'Texture' with an additional stencil buffer.
+colorStencilToTexture :: Int -- ^ Texture width.
+                      -> Int -- ^ Texture height.
+                      -> Layer' s t a
+                      -> Layer' NonDrawable t (a, TTexture t)
+colorStencilToTexture w h l =
+        fmap (\(x, [ct, _], _, _) -> (x, ct)) $
+                TextureLayer False [ColorLayer, DepthStencilLayer] (w, h)
+                             (0, 0, 0, 0) False False l
+
+-- | Draw a 'Layer' to a 'Texture', reading the content of the texture.
+colorToTexture' :: Int          -- ^ Texture width.
+                -> Int          -- ^ Texture height.
+                -> Int          -- ^ First pixel to read X.
+                -> Int          -- ^ First pixel to read Y.
+                -> Int          -- ^ Width of the rectangle to read.
+                -> Int          -- ^ Height of the rectangle to read.
+                -> Layer' s t a -- ^ Layer to draw.
+                -> Layer' NonDrawable t (a, TTexture t, [Color])
+colorToTexture' w h rx ry rw rh l =
+        fmap (\(x, [t, _], Just c, _) -> (x, t, c)) $
+                TextureLayer False [ColorLayer, DepthLayer] (w, h)
+                             (rx, ry, rw, rh) True False l
+
+-- | Draw a 'Layer' to a depth 'Texture', reading the content of the texture.
+-- Not supported on WebGL.
+depthToTexture' :: Int          -- ^ Texture width.
+                -> Int          -- ^ Texture height.
+                -> Int          -- ^ First pixel to read X.
+                -> Int          -- ^ First pixel to read Y.
+                -> Int          -- ^ Width of the rectangle to read.
+                -> Int          -- ^ Height of the rectangle to read.
+                -> Layer' s t a -- ^ Layer to draw.
+                -> Layer' NonDrawable t (a, TTexture t, [Word8])
+depthToTexture' w h rx ry rw rh l =
+        fmap (\(x, [t], _, Just d) -> (x, t, d)) $
+                TextureLayer False [DepthLayer] (w, h) (rx, ry, rw, rh)
+                             False True l
+
+-- | Combination of 'colorToTexture'' and 'depthToTexture''. Not supported
+-- on WebGL.
+colorDepthToTexture' :: Int             -- ^ Texture width.
+                     -> Int             -- ^ Texture height.
+                     -> Int             -- ^ First pixel to read X.
+                     -> Int             -- ^ First pixel to read Y.
+                     -> Int             -- ^ Width of the rectangle to read.
+                     -> Int             -- ^ Height of the rectangle to read.
+                     -> Layer' s t a    -- ^ Layer to draw.
+                     -> Layer' NonDrawable t
+                               (a, TTexture t, TTexture t, [Color], [Word8])
+colorDepthToTexture' w h rx ry rw rh l =
+        fmap (\(x, [ct, dt], Just c, Just d) -> (x, ct, dt, c, d)) $
+                TextureLayer False [ColorLayer, DepthLayer] (w, h)
+                             (rx, ry, rw, rh) True True l
+
+-- | 'colorToTexture'' with an additional stencil buffer.
+colorStencilToTexture' :: Int           -- ^ Texture width.
+                       -> Int           -- ^ Texture height.
+                       -> Int           -- ^ First pixel to read X.
+                       -> Int           -- ^ First pixel to read Y.
+                       -> Int           -- ^ Width of the rectangle to read.
+                       -> Int           -- ^ Height of the rectangle to read.
+                       -> Layer' s t a  -- ^ Layer to draw.
+                       -> Layer' NonDrawable t (a, TTexture t, [Color])
+colorStencilToTexture' w h rx ry rw rh l =
+        fmap (\(x, [t, _], Just c, _) -> (x, t, c)) $
+                TextureLayer False [ColorLayer, DepthStencilLayer] (w, h)
+                             (rx, ry, rw, rh) True False l
+
+-- | Draw a 'Layer' with multiple floating point colors
+-- (use 'Fragment2', 'Fragment3', etc.) to some 'Texture's and to a depth
+-- Texture.
+buffersDepthToTexture :: Int            -- ^ Texture width.
+                      -> Int            -- ^ Texture height.
+                      -> Int            -- ^ Number of colors.
+                      -> Layer' s t a   -- ^ Layer to draw.
+                      -> Layer' NonDrawable t (a, [TTexture t], TTexture t)
+buffersDepthToTexture w h n l =
+        fmap (\(x, dt : ts, _, _) -> (x, ts, dt)) $
+                TextureLayer True (DepthLayer : map BufferLayer [0 .. n - 1])
+                             (w, h) (0, 0, 0, 0) False False l
+
+-- | Draw a 'Layer' with multiple floating point colors
+-- (use 'Fragment2', 'Fragment3', etc.) to some 'Texture's with an additional
+-- stencil buffer.
+buffersStencilToTexture :: Int          -- ^ Texture width.
+                        -> Int          -- ^ Texture height.
+                        -> Int          -- ^ Number of colors.
+                        -> Layer' s t a -- ^ Layer to draw.
+                        -> Layer' NonDrawable t (a, [TTexture t])
+buffersStencilToTexture w h n l =
+        fmap (\(x, _ : ts, _, _) -> (x, ts)) $
+                TextureLayer True
+                             (DepthStencilLayer : map BufferLayer [0 .. n - 1])
+                             (w, h) (0, 0, 0, 0) False False l
diff --git a/Graphics/Rendering/Ombra/Shader.hs b/Graphics/Rendering/Ombra/Shader.hs
--- a/Graphics/Rendering/Ombra/Shader.hs
+++ b/Graphics/Rendering/Ombra/Shader.hs
@@ -32,8 +32,7 @@
 Required extensions:
 
 @
-\{\-# LANGUAGE DataKinds, RebindableSyntax, DeriveDataTypeable,
-             GeneralizedNewtypeDeriving, GADTs #\-\}
+\{\-# LANGUAGE DataKinds, RebindableSyntax, DeriveGeneric, GADTs #\-\}
 @
 
 -}
diff --git a/Graphics/Rendering/Ombra/Stencil.hs b/Graphics/Rendering/Ombra/Stencil.hs
--- a/Graphics/Rendering/Ombra/Stencil.hs
+++ b/Graphics/Rendering/Ombra/Stencil.hs
@@ -1,68 +1,10 @@
-module Graphics.Rendering.Ombra.Stencil where
-
-import Graphics.Rendering.Ombra.Internal.GL
-
--- | Stencil mode.
-data Mode = Mode (Side Function) (Side Operation) deriving Eq
-
-data Side a = FrontBack a       -- ^ Use the same value for both sides.
-            | Separate a a      -- ^ Use a different value for each side (front
-                                -- and back).
-            deriving Eq
-
--- | Function type, fragment stencil value and mask.
-data Function = Function FunctionType Int Word deriving Eq
-
--- | Operation to perform between the masked fragment stencil value and the
--- masked destination stencil value.
-data FunctionType = Never               -- ^ Never pass.
-                  | Always              -- ^ Always pass.
-                  | Less                -- ^ <
-                  | LessOrEqual         -- ^ <=
-                  | Greater             -- ^ >
-                  | GreaterOrEqual      -- ^ >=
-                  | Equal               -- ^ ==
-                  | NotEqual            -- ^ /=
-                  deriving Eq
-
--- | Operations to perform if the stencil test fails, if the stencil test passes
--- but the depth test fails, and if both the stencil test and the depth test
--- pass.
-data Operation = Operation OperationType OperationType OperationType deriving Eq
-
--- | Operation to perform to the stencil value in the buffer.
-data OperationType = Keep       -- ^ Keep it unchanged.
-                   | Invert     -- ^ Invert it.
-                   | Zero       -- ^ Set it to zero.
-                   | Replace    -- ^ Replace it with the masked fragment value.
-                   | Increment  -- ^ Increment it if not maximum.
-                   | Decrement  -- ^ Decrement it if not zero.
-                   | IncWrap    -- ^ Increment it, wrapping it if it would
-                                -- overflow.
-                   | DecWrap    -- ^ Decrement it, wrapping it if it would
-                                -- underflow.
-                   deriving Eq
-
-function :: GLES => Function -> (GLEnum, GLInt, GLUInt)
-function (Function ty value mask) = ( getType ty
-                                    , fromIntegral value
-                                    , fromIntegral mask )
-        where getType Never = gl_NEVER
-              getType Always = gl_ALWAYS
-              getType Less = gl_LESS
-              getType LessOrEqual = gl_LEQUAL
-              getType Greater = gl_GREATER
-              getType GreaterOrEqual = gl_GEQUAL
-              getType Equal = gl_EQUAL
-              getType NotEqual = gl_NOTEQUAL
+module Graphics.Rendering.Ombra.Stencil (
+        Mode(..),
+        Side(..),
+        Function(..),
+        FunctionType(..),
+        Operation(..),
+        OperationType(..)
+) where
 
-operation :: GLES => Operation -> (GLEnum, GLEnum, GLEnum)
-operation (Operation sf spdf spdp) = (getOp sf, getOp spdf, getOp spdp)
-        where getOp Keep = gl_KEEP
-              getOp Invert = gl_INVERT
-              getOp Zero = gl_ZERO
-              getOp Replace = gl_REPLACE
-              getOp Increment = gl_INCR
-              getOp Decrement = gl_DECR
-              getOp IncWrap = gl_INCR_WRAP
-              getOp DecWrap = gl_DECR_WRAP
+import Graphics.Rendering.Ombra.Stencil.Internal
diff --git a/Graphics/Rendering/Ombra/Stencil/Internal.hs b/Graphics/Rendering/Ombra/Stencil/Internal.hs
new file mode 100644
--- /dev/null
+++ b/Graphics/Rendering/Ombra/Stencil/Internal.hs
@@ -0,0 +1,68 @@
+module Graphics.Rendering.Ombra.Stencil.Internal where
+
+import Graphics.Rendering.Ombra.Internal.GL
+
+-- | Stencil mode.
+data Mode = Mode (Side Function) (Side Operation) deriving Eq
+
+data Side a = FrontBack a       -- ^ Use the same value for both sides.
+            | Separate a a      -- ^ Use a different value for each side (front
+                                -- and back).
+            deriving Eq
+
+-- | Function type, fragment stencil value and mask.
+data Function = Function FunctionType Int Word deriving Eq
+
+-- | Operation to perform between the masked fragment stencil value and the
+-- masked destination stencil value.
+data FunctionType = Never               -- ^ Never pass.
+                  | Always              -- ^ Always pass.
+                  | Less                -- ^ <
+                  | LessOrEqual         -- ^ <=
+                  | Greater             -- ^ >
+                  | GreaterOrEqual      -- ^ >=
+                  | Equal               -- ^ ==
+                  | NotEqual            -- ^ /=
+                  deriving Eq
+
+-- | Operations to perform if the stencil test fails, if the stencil test passes
+-- but the depth test fails, and if both the stencil test and the depth test
+-- pass.
+data Operation = Operation OperationType OperationType OperationType deriving Eq
+
+-- | Operation to perform to the stencil value in the buffer.
+data OperationType = Keep       -- ^ Keep it unchanged.
+                   | Invert     -- ^ Invert it.
+                   | Zero       -- ^ Set it to zero.
+                   | Replace    -- ^ Replace it with the masked fragment value.
+                   | Increment  -- ^ Increment it if not maximum.
+                   | Decrement  -- ^ Decrement it if not zero.
+                   | IncWrap    -- ^ Increment it, wrapping it if it would
+                                -- overflow.
+                   | DecWrap    -- ^ Decrement it, wrapping it if it would
+                                -- underflow.
+                   deriving Eq
+
+function :: GLES => Function -> (GLEnum, GLInt, GLUInt)
+function (Function ty value mask) = ( getType ty
+                                    , fromIntegral value
+                                    , fromIntegral mask )
+        where getType Never = gl_NEVER
+              getType Always = gl_ALWAYS
+              getType Less = gl_LESS
+              getType LessOrEqual = gl_LEQUAL
+              getType Greater = gl_GREATER
+              getType GreaterOrEqual = gl_GEQUAL
+              getType Equal = gl_EQUAL
+              getType NotEqual = gl_NOTEQUAL
+
+operation :: GLES => Operation -> (GLEnum, GLEnum, GLEnum)
+operation (Operation sf spdf spdp) = (getOp sf, getOp spdf, getOp spdp)
+        where getOp Keep = gl_KEEP
+              getOp Invert = gl_INVERT
+              getOp Zero = gl_ZERO
+              getOp Replace = gl_REPLACE
+              getOp Increment = gl_INCR
+              getOp Decrement = gl_DECR
+              getOp IncWrap = gl_INCR_WRAP
+              getOp DecWrap = gl_DECR_WRAP
diff --git a/Graphics/Rendering/Ombra/Texture.hs b/Graphics/Rendering/Ombra/Texture.hs
--- a/Graphics/Rendering/Ombra/Texture.hs
+++ b/Graphics/Rendering/Ombra/Texture.hs
@@ -4,7 +4,8 @@
         mkTextureFloat,
         mkTextureRaw,
         Filter(..),
-        setFilter
+        setFilter,
+        colorTex
 ) where
 
 import Data.Hashable
@@ -58,3 +59,7 @@
 setFilter min mag (TextureImage (TextureFloat c _ _ w h s)) =
         TextureImage (TextureFloat c min mag w h s)
 setFilter _ _ t = t
+
+-- | Generate a 1x1 texture.
+colorTex :: GLES => Color -> Texture
+colorTex c = mkTexture 1 1 [ c ]
diff --git a/ombra.cabal b/ombra.cabal
--- a/ombra.cabal
+++ b/ombra.cabal
@@ -1,5 +1,5 @@
 name:                ombra
-version:             0.2.1.0
+version:             0.2.2.0
 synopsis:            Render engine.
 description:         Type-safe render engine, with a purely functional API and a shader EDSL. Ombra supports both OpenGL (2.0 with some extensions) and WebGL, through GHCJS.
 homepage:            https://github.com/ziocroc/Ombra
@@ -28,7 +28,7 @@
 
 library
   exposed-modules:     Graphics.Rendering.Ombra, Graphics.Rendering.Ombra.Blend, Graphics.Rendering.Ombra.Layer, Graphics.Rendering.Ombra.Object, Graphics.Rendering.Ombra.Texture, Graphics.Rendering.Ombra.Stencil, Graphics.Rendering.Ombra.Shader, Graphics.Rendering.Ombra.Transformation, Graphics.Rendering.Ombra.Draw, Graphics.Rendering.Ombra.D2, Graphics.Rendering.Ombra.Geometry, Graphics.Rendering.Ombra.D3, Graphics.Rendering.Ombra.Color, Graphics.Rendering.Ombra.Backend, Graphics.Rendering.Ombra.Shapes, Graphics.Rendering.Ombra.Internal.GL, Graphics.Rendering.Ombra.Shader.Default3D, Graphics.Rendering.Ombra.Shader.Default2D
-  other-modules:       Graphics.Rendering.Ombra.Internal.Resource, Graphics.Rendering.Ombra.Internal.TList, Graphics.Rendering.Ombra.Shader.ShaderVar, Graphics.Rendering.Ombra.Shader.GLSL, Graphics.Rendering.Ombra.Shader.Stages, Graphics.Rendering.Ombra.Shader.Program, Graphics.Rendering.Ombra.Shader.CPU, Graphics.Rendering.Ombra.Shader.Language.Types, Graphics.Rendering.Ombra.Shader.Language.Functions, Graphics.Rendering.Ombra.Draw.Internal, Graphics.Rendering.Ombra.Layer.Internal, Graphics.Rendering.Ombra.Object.Internal, Graphics.Rendering.Ombra.Geometry.Internal, Graphics.Rendering.Ombra.Texture.Internal
+  other-modules:       Graphics.Rendering.Ombra.Internal.Resource, Graphics.Rendering.Ombra.Internal.TList, Graphics.Rendering.Ombra.Shader.ShaderVar, Graphics.Rendering.Ombra.Shader.GLSL, Graphics.Rendering.Ombra.Shader.Stages, Graphics.Rendering.Ombra.Shader.Program, Graphics.Rendering.Ombra.Shader.CPU, Graphics.Rendering.Ombra.Shader.Language.Types, Graphics.Rendering.Ombra.Shader.Language.Functions, Graphics.Rendering.Ombra.Draw.Internal, Graphics.Rendering.Ombra.Layer.Internal, Graphics.Rendering.Ombra.Object.Internal, Graphics.Rendering.Ombra.Geometry.Internal, Graphics.Rendering.Ombra.Texture.Internal, Graphics.Rendering.Ombra.Blend.Internal, Graphics.Rendering.Ombra.Stencil.Internal
 
   if flag(webgl)
     exposed-modules:   Graphics.Rendering.Ombra.Backend.WebGL