Start work on old picture shader code

src/Picture/Data.hs

@@ -34,8 +34,23 @@ layerNum = fromEnum
 numLayers :: Int
 numLayers = length [minBound :: Layer .. maxBound]
 
-newtype ShadNum = ShadNum {_unShadNum :: Int}
-    deriving (Eq, Ord, Show, Read) --Generic, Flat)
+data ShadNum
+    = PolyShad
+    | PolyzShad
+    | BezShad
+    | TextShad
+    | ArcShad
+    | EllShad
+    deriving (Eq, Ord, Enum, Bounded, Show, Read) --Generic, Flat)
+
+numShads :: Int
+numShads = length [minBound :: ShadNum .. maxBound]
+
+_unShadNum :: ShadNum -> Int
+_unShadNum = fromEnum
+
+toShadNum :: Int -> ShadNum
+toShadNum = toEnum
 
 polyNum, polyzNum, bezNum, textNum, arcNum, ellNum :: ShadNum
 {-# INLINE polyNum #-}
@@ -44,12 +59,12 @@ polyNum, polyzNum, bezNum, textNum, arcNum, ellNum :: ShadNum
 {-# INLINE textNum #-}
 {-# INLINE arcNum #-}
 {-# INLINE ellNum #-}
-polyNum = ShadNum 0
-polyzNum = ShadNum 1
-bezNum = ShadNum 2
-textNum = ShadNum 3
-arcNum = ShadNum 4
-ellNum = ShadNum 5
+polyNum = toShadNum 0
+polyzNum = toShadNum 1
+bezNum = toShadNum 2
+textNum = toShadNum 3
+arcNum = toShadNum 4
+ellNum = toShadNum 5
 
 type Picture = [Verx]