{-
Obj3d.hs - Objects

Objects are the basic unit of 3d.
-}

module Obj3d where

import Vec3d
import Mat3d
import Tri3d

import qualified GraphicsUtils as G

type Obj3 a = [Tri3 a]
type Obj2 a = [Tri2 a]

{- Partition function used for the qsort -}
partition pvt (h:t) lt ge = if (averageZ h) < (averageZ pvt)
			    then partition pvt t lt (h:ge)
			    else partition pvt t (h:lt) ge
partition pvt [] lt ge = (lt,ge)

strObj3 :: Obj3 a -> IO ()
strObj3 (h:t) = do print ((show x) ++ ", " ++  (show y) ++ ", " ++ (show z))
		   strObj3 t
    where (x,y,z,_) = h
strObj3 [] = return ()

strObj2 :: Obj2 a -> IO ()
strObj2 (h:t) = do print ((show x) ++ ", " ++ (show y) ++ ", " ++ (show z))
		   strObj2 t
    where (x,y,z,_) = h
strObj2 [] = return ()

{- qsort the tri's in the object. -}
zSortObj :: Obj3 a -> Obj3 a
zSortObj (h:t) = (zSortObj front) ++ mid ++ (zSortObj back)
    where (front, back) = partition h t [] []
	  mid = [h]
zSortObj [] = []


{- Transform objects -}
rotObjX :: Obj3 a -> Float -> Obj3 a
rotObjX objs theta = map (\x->x `rotTriX` theta) objs


rotObjY :: Obj3 a -> Float -> Obj3 a
rotObjY objs theta = map (\x->x `rotTriY` theta) objs


rotObjZ :: Obj3 a -> Float -> Obj3 a
rotObjZ objs theta = map (\x->x `rotTriZ` theta) objs


flattenObj :: Obj3 a -> (Vector3 -> Vector2) -> Obj2 a
flattenObj objs f = map (\x-> x `flatten` f) objs


backFaceCull :: Obj2 a -> Obj2 a
backFaceCull (h:t) = if not (zSign h)
		     then h : (backFaceCull t)
		     else (backFaceCull t)
backFaceCull [] = []

drawObj2 :: G.Window -> Obj2 a -> (Tri2 a -> G.Graphic) -> IO ()
drawObj2 w (h:t) f = do G.drawInWindow w (f h)
			drawObj2 w t f
drawObj2 w [] f = return () 


drawObj3 :: G.Window -> Obj3 a -> (Tri2 a -> G.Graphic) -> IO ()
drawObj3 w objs f = drawObj2 w (prepObj objs) f

	  
prepObj :: Obj3 a -> Obj2 a
prepObj objs = obj2
    where objs' = zSortObj objs
	  obj2 = flattenObj objs' (deriveVec3To2 20.0)
--	  obj2' = backFaceCull obj2
	  
rotObj :: Obj3 a -> Float -> Float -> Float -> Obj3 a
rotObj obj x y z = obj'''
    where obj' = obj `rotObjX` x
	  obj'' = obj' `rotObjY` y
	  obj''' = obj'' `rotObjZ` z