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module MtlParser
( ObjMaterial (..)
, MtlLib
, parseMtl
, readMtl
) where
import Data.Map (Map)
import qualified Data.Map as Map
import Data.Maybe
import Control.Monad.State.Strict
import Control.Monad.Writer
import Data.Text (pack,Text)
type Vec3 = (Float,Float,Float)
type MtlLib = Map Text ObjMaterial
data ObjMaterial
= ObjMaterial
{ mtl_Name :: Text
, mtl_Ka :: Vec3 -- ambient color
, mtl_Kd :: Vec3 -- diffuse color
, mtl_Ks :: Vec3 -- specular color
, mtl_illum :: Int
, mtl_Tr :: Float -- transparency
, mtl_Ns :: Float -- specular exponent
, mtl_map_Kd :: Maybe String -- diffuse texture file name
}
deriving (Eq,Show)
newMaterial name = ObjMaterial
{ mtl_Name = name
, mtl_Ka = (1, 1, 1)
, mtl_Kd = (1, 1, 1)
, mtl_Ks = (0, 0, 0)
, mtl_illum = 1
, mtl_Tr = 1
, mtl_Ns = 0
, mtl_map_Kd = Nothing
}
type Mtl = WriterT [ObjMaterial] (State (Maybe ObjMaterial))
readMaybe :: Read a => String -> Maybe a
readMaybe s = case reads s of
[(val, "")] -> Just val
_ -> Nothing
readVec3 :: String -> String -> String -> Maybe Vec3
readVec3 r g b = (,,) <$> readMaybe r <*> readMaybe g <*> readMaybe b
setAttr = modify' . fmap
addMaterial = gets maybeToList >>= tell
parseLine :: String -> Mtl ()
parseLine s = case words $ takeWhile (/='#') s of
["newmtl",name] -> do
addMaterial
put $ Just $ newMaterial $ pack name
["map_Kd",textureName] -> setAttr (\s -> s {mtl_map_Kd = Just textureName})
["Ka",r,g,b] | Just rgb <- readVec3 r g b -> setAttr (\s -> s {mtl_Ka = rgb})
["Kd",r,g,b] | Just rgb <- readVec3 r g b -> setAttr (\s -> s {mtl_Kd = rgb})
["Ks",r,g,b] | Just rgb <- readVec3 r g b -> setAttr (\s -> s {mtl_Ks = rgb})
["illum",a] | Just v <- readMaybe a -> setAttr (\s -> s {mtl_illum = v})
["Tr",a] | Just v <- readMaybe a -> setAttr (\s -> s {mtl_Tr = v})
["Ns",a] | Just v <- readMaybe a -> setAttr (\s -> s {mtl_Ns = v})
_ -> return ()
parseMtl :: String -> MtlLib
parseMtl src = Map.fromList [(mtl_Name m,m) | m <- evalState (execWriterT (mapM_ parseLine (lines src) >> addMaterial)) Nothing]
readMtl :: String -> IO MtlLib
readMtl fname = parseMtl <$> readFile fname
|
