    --------------------------------------------------------------------------------
    -- |
    -- Module      :  Graphics.Rendering.OpenGL.GL.Hints
    -- 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 module corresponds to section 5.6 (Hints) of the OpenGL 2.1 specs.
    --
    --------------------------------------------------------------------------------

    module Graphics.Rendering.OpenGL.GL.Hints (
       HintTarget(..), HintMode(..), hint
    ) where

    import Graphics.Rendering.OpenGL.GL.BasicTypes ( GLenum )
    import Graphics.Rendering.OpenGL.GL.QueryUtils (
       GetPName(GetPerspectiveCorrectionHint,GetPointSmoothHint,GetLineSmoothHint,
                GetPolygonSmoothHint,GetFogHint,GetGenerateMipmapHint,
                GetTextureCompressionHint,GetPackCMYKHint,GetUnpackCMYKHint),
       getEnum1 )
    import Graphics.Rendering.OpenGL.GL.StateVar ( StateVar, makeStateVar )

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

    data HintTarget =
         PerspectiveCorrection
       | PointSmooth
       | LineSmooth
       | PolygonSmooth
       | Fog
       | GenerateMipmap
       | TextureCompression
       | PackCMYK
       | UnpackCMYK
       deriving ( Eq, Ord, Show )

    marshalHintTarget :: HintTarget -> GLenum
    marshalHintTarget x = case x of
       PerspectiveCorrection -> 0xc50
       PointSmooth -> 0xc51
       LineSmooth -> 0xc52
       PolygonSmooth -> 0xc53
       Fog -> 0xc54
       GenerateMipmap -> 0x8192
       TextureCompression -> 0x84ef
       PackCMYK -> 0x800e
       UnpackCMYK -> 0x800f

    hintTargetToGetPName :: HintTarget -> GetPName
    hintTargetToGetPName x = case x of
       PerspectiveCorrection -> GetPerspectiveCorrectionHint
       PointSmooth -> GetPointSmoothHint
       LineSmooth -> GetLineSmoothHint
       PolygonSmooth -> GetPolygonSmoothHint
       Fog -> GetFogHint
       GenerateMipmap -> GetGenerateMipmapHint
       TextureCompression -> GetTextureCompressionHint
       PackCMYK -> GetPackCMYKHint
       UnpackCMYK -> GetUnpackCMYKHint

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

    data HintMode =
         DontCare
       | Fastest
       | Nicest
       deriving ( Eq, Ord, Show )

    marshalHintMode :: HintMode -> GLenum
    marshalHintMode x = case x of
       DontCare -> 0x1100
       Fastest -> 0x1101
       Nicest -> 0x1102

    unmarshalHintMode :: GLenum -> HintMode
    unmarshalHintMode x
       | x == 0x1100 = DontCare
       | x == 0x1101 = Fastest
       | x == 0x1102 = Nicest
       | otherwise = error ("unmarshalHintMode: illegal value " ++ show x)

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

    hint ::  HintTarget -> StateVar HintMode
    hint t =
       makeStateVar
          (getEnum1 unmarshalHintMode (hintTargetToGetPName t))
          (glHint (marshalHintTarget t) . marshalHintMode)

    foreign import CALLCONV unsafe "glHint" glHint :: GLenum -> GLenum -> IO ()