{- Textures.hs; Mun Hon Cheong (mhch295@cse.unsw.edu.au) 2005

This module is for loading textures

-}

module Graphics.SceneGraph.Textures where

import Graphics.UI.GLUT
import Graphics.SceneGraph.ReadImage (readImage)
import Monad (when)
import Graphics.SceneGraph.TGA
import Data.Word
import Foreign.Marshal.Alloc


-- read a list of images and returns a list of textures
-- all images are assumed to be in the TGA image format
getAndCreateTextures :: [String] -> IO [Maybe TextureObject]
getAndCreateTextures fileNames = do
   fileNamesExts <- return (map (++".tga") fileNames)
   texData <- mapM readImageC fileNamesExts
   texObjs <- mapM createTexture texData
   return texObjs


-- read a single texture
getAndCreateTexture :: String -> IO (Maybe TextureObject)
getAndCreateTexture fileName = do
   texData <- readImageC (fileName++".tga")
   texObj <- createTexture texData
   return texObj


-- read the image data
readImageC :: String -> IO (Maybe (Size, PixelData Word8))
readImageC path = catch (readTga path) (\err -> do
   print ("missing texture: "++path)
   return Nothing)


-- creates the texture
createTexture :: (Maybe (Size, PixelData a)) -> IO (Maybe TextureObject)
createTexture (Just ((Size x y), pixels@(PixelData t1 t2 ptr))) = do
   [texName] <- genObjectNames 1  -- generate our texture.
   --rowAlignment  Unpack $= 1
   textureBinding Texture2D $= Just texName  -- make our new texture the current texture.
   --generateMipmap Texture2D $= Enabled
   build2DMipmaps Texture2D RGBA' (fromIntegral x) (fromIntegral y) pixels
   textureFilter  Texture2D $= ((Linear', Just Nearest), Linear')
   --textureWrapMode Texture2D S $= (Repeated, Repeat)
   --textureWrapMode Texture2D T $= (Repeated, Repeat)
   textureFunction $= Modulate
   free ptr
   return (Just texName)
createTexture Nothing = return Nothing