    -- #hide
    --------------------------------------------------------------------------------
    -- |
    -- Module      :  Graphics.Rendering.OpenGL.GL.Texturing.TextureUnit
    -- 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 (un-)marshaling TextureUnit.
    --
    --------------------------------------------------------------------------------

    module Graphics.Rendering.OpenGL.GL.Texturing.TextureUnit (
       TextureUnit(..), marshalTextureUnit, unmarshalTextureUnit
    ) where

    import Graphics.Rendering.OpenGL.GL.BasicTypes ( GLenum, GLuint )

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

    -- | Identifies a texture unit via its number, which must be in the range of
    -- (0 .. 'maxTextureUnit').

    newtype TextureUnit = TextureUnit GLuint
       deriving ( Eq, Ord, Show )

    marshalTextureUnit :: TextureUnit -> GLenum
    marshalTextureUnit (TextureUnit x) = 0x84c0 + fromIntegral x

    unmarshalTextureUnit :: GLenum -> TextureUnit
    unmarshalTextureUnit x = TextureUnit (fromIntegral (x - 0x84c0))