    --------------------------------------------------------------------------------
    -- |
    -- Module      :  Graphics.UI.GLUT.Objects
    -- Copyright   :  (c) Sven Panne 2002-2013
    -- License     :  BSD3
    --
    -- Maintainer  :  Sven Panne <svenpanne@gmail.com>
    -- Stability   :  stable
    -- Portability :  portable
    --
    -- GLUT includes a number of routines for generating easily recognizable 3D
    -- geometric objects. These routines reflect functionality available in the
    -- @aux@ toolkit described in the /OpenGL Programmer\'s Guide/ and are included
    -- in GLUT to allow the construction of simple GLUT programs that render
    -- recognizable objects. These routines can be implemented as pure OpenGL
    -- rendering routines. The routines do not generate display lists for the
    -- objects they create. The routines generate normals appropriate for lighting
    -- but do not generate texture coordinates (except for the solid teapot, teacup
    -- and teaspoon). If VBOs should be used instead of the fixed function pipeline,
    -- specify at least one of the attribute locations
    -- 'Graphics.UI.GLUT.State.vertexAttribCoord3' or
    -- 'Graphics.UI.GLUT.State.vertexAttribNormal'.
    --
    --------------------------------------------------------------------------------

    module Graphics.UI.GLUT.Objects (
       -- * Rendering flavour
       Flavour(..),

       -- * Object description
       Object(..),

       -- * Type synonyms
       Sides, Rings, NumLevels,

       -- * Rendering
       renderObject
    ) where

    import Control.Monad.IO.Class ( MonadIO(..) )
    import Foreign.C.Types ( CInt )
    import Foreign.Marshal.Utils ( with )
    import Foreign.Ptr ( Ptr, castPtr )
    import Graphics.Rendering.OpenGL ( Height, Radius, Slices, Stacks, Vertex3(..) )
    import Graphics.Rendering.OpenGL.Raw.Types ( GLdouble, GLint )

    import Graphics.UI.GLUT.Raw

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

    -- | Flavour of object rendering

    data Flavour
       = -- | Object is rendered as a solid with shading and surface normals.
         Solid
       | -- | Object is rendered as a wireframe without surface normals.
         Wireframe
       deriving ( Eq, Ord, Show )

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

    -- | GLUT offers five types of objects:
    --
    -- *  The five Platonic solids, see
    --    <http://mathworld.wolfram.com/PlatonicSolid.html>.
    --
    -- * A rhombic dodecahedron, see
    --   <http://mathworld.wolfram.com/RhombicDodecahedron.html>.
    --
    -- * Approximations to rounded objects.
    --
    -- * The classic teaset modeled by Martin Newell in 1975. Both surface normals
    --   and texture coordinates for the teaset are generated.
    --
    -- * A Sierpinski sponge, see
    --   <http://mathworld.wolfram.com/Tetrix.html>.

    data Object
       = -- | A cube centered at the modeling coordinates origin with sides of the
         --   given length.
         Cube Height
       | -- | A dodecahedron (12-sided regular solid) centered at the modeling
         --   coordinates origin with a radius of @sqrt 3@.
         Dodecahedron
       | -- | A icosahedron (20-sided regular solid) centered at the modeling
         --   coordinates origin with a radius of 1.0.
         Icosahedron
       | -- | Render a solid octahedron (8-sided regular solid) centered at the
         --   modeling coordinates origin with a radius of 1.0.
         Octahedron
       | -- | Render a solid tetrahedron (4-sided regular solid) centered at the
         --   modeling coordinates origin with a radius of @sqrt 3@.
         Tetrahedron
       | -- | (/freeglut only/) A rhombic dodecahedron whose corners are at most a
         -- distance of one from the origin. The rhombic dodecahedron has faces
         -- which are identical rhombi, but which have some vertices at which three
         -- faces meet and some vertices at which four faces meet. The length of
         -- each side is @(sqrt 3)\/2@. Vertices at which four faces meet are found
         -- at @(0, 0, +\/-1)@ and @(+\/-(sqrt 2)\/2, +\/-(sqrt 2)\/2, 0)@.
         RhombicDodecahedron
       | -- | A sphere centered at the modeling coordinates origin of the specified
         --   radius. The sphere is subdivided around the Z axis into slices
         --   (similar to lines of longitude) and along the Z axis into stacks
         --   (similar to lines of latitude).
         Sphere' Radius Slices Stacks
       | -- | A cone oriented along the Z axis. The base of the cone is placed at Z
         --   = 0, and the top at Z = the given height. The cone is subdivided
         --   around the Z axis into slices, and along the Z axis into stacks.
         Cone Radius Height Slices Stacks
       | -- |(/freeglut only/) A cylinder oriented along the Z axis. The base of the
         --  cylinder is placed at Z = 0, and the top at Z = the given height. The
         --  cylinder is subdivided around the Z axis into slices, and along the Z
         -- axis into stacks.
         Cylinder' Radius Height Slices Stacks
       | -- | A torus (doughnut) centered at the modeling coordinates origin
         -- whose axis is aligned with the Z axis. The torus is described by its
         -- inner and outer radius, the number of sides for each radial section,
         -- and the number of radial divisions (rings).
         Torus Radius Radius Sides Rings
       | -- | A teapot with a given relative size.
         Teapot Height
       | -- |(/freeglut only/) A teacup with a given relative size.
         Teacup Height
       | -- |(/freeglut only/) A teaspoon with a given relative size.
         Teaspoon Height
       | -- |(/freeglut only/) A Sierpinski sponge of a given level, where a level
         -- 0 sponge is the same as a 'Tetrahedron'.
         SierpinskiSponge NumLevels
       deriving ( Eq, Ord, Show )

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

    type Sides     = GLint
    type Rings     = GLint
    type NumLevels = GLint

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

    -- | Render an object in the given flavour.

    renderObject :: MonadIO m => Flavour -> Object -> m ()
    renderObject Solid     (Cube h)             = glutSolidCube h
    renderObject Wireframe (Cube h)             = glutWireCube  h
    renderObject Solid     Dodecahedron         = glutSolidDodecahedron
    renderObject Wireframe Dodecahedron         = glutWireDodecahedron
    renderObject Solid     Icosahedron          = glutSolidIcosahedron
    renderObject Wireframe Icosahedron          = glutWireIcosahedron
    renderObject Solid     Octahedron           = glutSolidOctahedron
    renderObject Wireframe Octahedron           = glutWireOctahedron
    renderObject Solid     Tetrahedron          = glutSolidTetrahedron
    renderObject Wireframe Tetrahedron          = glutWireTetrahedron
    renderObject Solid     RhombicDodecahedron  = glutSolidRhombicDodecahedron
    renderObject Wireframe RhombicDodecahedron  = glutWireRhombicDodecahedron
    renderObject Solid     (Sphere' r s t)      = glutSolidSphere r s t
    renderObject Wireframe (Sphere' r s t)      = glutWireSphere  r s t
    renderObject Solid     (Cone r h s t)       = glutSolidCone r h s t
    renderObject Wireframe (Cone r h s t)       = glutWireCone  r h s t
    renderObject Solid     (Cylinder' r h s t)  = glutSolidCylinder r h s t
    renderObject Wireframe (Cylinder' r h s t)  = glutWireCylinder r h s t
    renderObject Solid     (Torus i o s r)      = glutSolidTorus i o s r
    renderObject Wireframe (Torus i o s r)      = glutWireTorus  i o s r
    renderObject Solid     (Teapot h)           = glutSolidTeapot h
    renderObject Wireframe (Teapot h)           = glutWireTeapot  h
    renderObject Solid     (Teacup h)           = glutSolidTeacup h
    renderObject Wireframe (Teacup h)           = glutWireTeacup  h
    renderObject Solid     (Teaspoon h)         = glutSolidTeaspoon h
    renderObject Wireframe (Teaspoon h)         = glutWireTeaspoon  h
    renderObject Solid     (SierpinskiSponge n) = solidSierpinskiSponge n
    renderObject Wireframe (SierpinskiSponge n) = wireSierpinskiSponge n

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

    solidSierpinskiSponge :: MonadIO m => NumLevels -> m ()
    solidSierpinskiSponge = sierpinskiSponge glutSolidSierpinskiSponge

    wireSierpinskiSponge :: MonadIO m => NumLevels -> m ()
    wireSierpinskiSponge = sierpinskiSponge glutWireSierpinskiSponge

    -- for consistency, we hide the offset and scale on the Haskell side
    sierpinskiSponge :: MonadIO m => (CInt -> Ptr GLdouble -> Height -> IO ()) -> NumLevels -> m ()
    sierpinskiSponge f n = liftIO $
       with (Vertex3 0 0 0) $ \offsetBuf ->
          f (fromIntegral n) ((castPtr :: Ptr (Vertex3 GLdouble) -> Ptr GLdouble) offsetBuf) 1