    -- #hide
    --------------------------------------------------------------------------------
    -- |
    -- Module      :  Graphics.Rendering.OpenGL.GL.ControlPoint
    -- Copyright   :  (c) Sven Panne 2002-2006
    -- License     :  BSD-style (see the file libraries/OpenGL/LICENSE)
    --
    -- Maintainer  :  sven.panne@aedion.de
    -- Stability   :  stable
    -- Portability :  portable
    --
    -- This is a purely internal module for handling control points.
    --
    --------------------------------------------------------------------------------

    module Graphics.Rendering.OpenGL.GL.ControlPoint (
       ControlPoint(..)
    ) where

    import Foreign.Ptr ( Ptr )
    import Foreign.Storable ( Storable(peek,poke) )
    import Graphics.Rendering.OpenGL.GL.BasicTypes ( GLenum )
    import Graphics.Rendering.OpenGL.GL.Capability ( EnableCap(..) )
    import Graphics.Rendering.OpenGL.GL.Domain ( Domain )
    import Graphics.Rendering.OpenGL.GL.VertexArrays ( Stride )
    import Graphics.Rendering.OpenGL.GL.VertexSpec (
       Vertex3, Vertex4, Index1, Color4, Normal3, TexCoord1, TexCoord2, TexCoord3,
       TexCoord4 )

    --------------------------------------------------------------------------------

    class ControlPoint c where
       map1Target       :: Domain d => c d -> GLenum
       map2Target       :: Domain d => c d -> GLenum
       enableCap1       :: Domain d => c d -> EnableCap
       enableCap2       :: Domain d => c d -> EnableCap
       numComponents    :: Domain d => c d -> Stride
       peekControlPoint :: Domain d => Ptr (c d) -> IO (c d)
       pokeControlPoint :: Domain d => Ptr (c d) -> (c d) -> IO ()

    instance ControlPoint Vertex3 where
       map1Target       = marshalMapTarget . const Map1Vertex3
       map2Target       = marshalMapTarget . const Map2Vertex3
       enableCap1       = const CapMap1Vertex3
       enableCap2       = const CapMap2Vertex3
       numComponents    = const 3
       peekControlPoint = peek
       pokeControlPoint = poke

    instance ControlPoint Vertex4 where
       map1Target       = marshalMapTarget . const Map1Vertex4
       map2Target       = marshalMapTarget . const Map2Vertex4
       enableCap1       = const CapMap1Vertex4
       enableCap2       = const CapMap2Vertex4
       numComponents    = const 4
       peekControlPoint = peek
       pokeControlPoint = poke

    instance ControlPoint Index1 where
       map1Target       = marshalMapTarget . const Map1Index
       map2Target       = marshalMapTarget . const Map2Index
       enableCap1       = const CapMap1Index
       enableCap2       = const CapMap2Index
       numComponents    = const 1
       peekControlPoint = peek
       pokeControlPoint = poke

    instance ControlPoint Color4 where
       map1Target       = marshalMapTarget . const Map1Color4
       map2Target       = marshalMapTarget . const Map2Color4
       enableCap1       = const CapMap1Color4
       enableCap2       = const CapMap2Color4
       numComponents    = const 4
       peekControlPoint = peek
       pokeControlPoint = poke

    instance ControlPoint Normal3 where
       map1Target       = marshalMapTarget . const Map1Normal
       map2Target       = marshalMapTarget . const Map2Normal
       enableCap1       = const CapMap1Normal
       enableCap2       = const CapMap2Normal
       numComponents    = const 3
       peekControlPoint = peek
       pokeControlPoint = poke

    instance ControlPoint TexCoord1 where
       map1Target       = marshalMapTarget . const Map1TextureCoord1
       map2Target       = marshalMapTarget . const Map2TextureCoord1
       enableCap1       = const CapMap1TextureCoord1
       enableCap2       = const CapMap2TextureCoord1
       numComponents    = const 1
       peekControlPoint = peek
       pokeControlPoint = poke

    instance ControlPoint TexCoord2 where
       map1Target       = marshalMapTarget . const Map1TextureCoord2
       map2Target       = marshalMapTarget . const Map2TextureCoord2
       enableCap1       = const CapMap1TextureCoord2
       enableCap2       = const CapMap2TextureCoord2
       numComponents    = const 2
       peekControlPoint = peek
       pokeControlPoint = poke

    instance ControlPoint TexCoord3 where
       map1Target       = marshalMapTarget . const Map1TextureCoord3
       map2Target       = marshalMapTarget . const Map2TextureCoord3
       enableCap1       = const CapMap1TextureCoord3
       enableCap2       = const CapMap2TextureCoord3
       numComponents    = const 3
       peekControlPoint = peek
       pokeControlPoint = poke

    instance ControlPoint TexCoord4 where
       map1Target       = marshalMapTarget . const Map1TextureCoord4
       map2Target       = marshalMapTarget . const Map2TextureCoord4
       enableCap1       = const CapMap1TextureCoord4
       enableCap2       = const CapMap2TextureCoord4
       numComponents    = const 4
       peekControlPoint = peek
       pokeControlPoint = poke

    --------------------------------------------------------------------------------

    data MapTarget =
         Map1Color4
       | Map1Index
       | Map1Normal
       | Map1TextureCoord1
       | Map1TextureCoord2
       | Map1TextureCoord3
       | Map1TextureCoord4
       | Map1Vertex3
       | Map1Vertex4
       | Map2Color4
       | Map2Index
       | Map2Normal
       | Map2TextureCoord1
       | Map2TextureCoord2
       | Map2TextureCoord3
       | Map2TextureCoord4
       | Map2Vertex3
       | Map2Vertex4

    marshalMapTarget :: MapTarget -> GLenum
    marshalMapTarget x = case x of
       Map1Color4 -> 0xd90
       Map1Index -> 0xd91
       Map1Normal -> 0xd92
       Map1TextureCoord1 -> 0xd93
       Map1TextureCoord2 -> 0xd94
       Map1TextureCoord3 -> 0xd95
       Map1TextureCoord4 -> 0xd96
       Map1Vertex3 -> 0xd97
       Map1Vertex4 -> 0xd98
       Map2Color4 -> 0xdb0
       Map2Index -> 0xdb1
       Map2Normal -> 0xdb2
       Map2TextureCoord1 -> 0xdb3
       Map2TextureCoord2 -> 0xdb4
       Map2TextureCoord3 -> 0xdb5
       Map2TextureCoord4 -> 0xdb6
       Map2Vertex3 -> 0xdb7
       Map2Vertex4 -> 0xdb8