    -- #hide
    --------------------------------------------------------------------------------
    -- |
    -- Module      :  Graphics.Rendering.OpenGL.GL.Face
    -- Copyright   :  (c) Sven Panne 2002-2009
    -- 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 (un-)marshaling Face.
    --
    --------------------------------------------------------------------------------

    module Graphics.Rendering.OpenGL.GL.Face (
       Face(..), marshalFace, unmarshalFace
    ) where

    import Graphics.Rendering.OpenGL.Raw.Core31

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

    data Face =
         Front
       | Back
       | FrontAndBack
       deriving ( Eq, Ord, Show )

    marshalFace :: Face -> GLenum
    marshalFace x = case x of
       Front -> gl_FRONT
       Back -> gl_BACK
       FrontAndBack -> gl_FRONT_AND_BACK

    unmarshalFace :: GLenum -> Face
    unmarshalFace x
       | x == gl_FRONT = Front
       | x == gl_BACK = Back
       | x == gl_FRONT_AND_BACK = FrontAndBack
       | otherwise = error ("unmarshalFace: illegal value " ++ show x)