Implement (not fully working) alternate shadow volumes

src/Shape/Data.hs

@@ -18,7 +18,7 @@ shVfromList = id
 
 {-# INLINE shEfromList #-}
 shEfromList = id
-newtype ShapeType = TopPrism Int
+newtype ShapeType = TopPrism { _prismSize :: Int }
     deriving newtype (Eq, Ord, Show, Read)
     --deriving stock Generic
     --deriving anyclass Flat
@@ -43,6 +43,7 @@ pairToSV = uncurry ShapeV
 
 makeLenses ''ShapeV
 makeLenses ''ShapeObj
+makeLenses ''ShapeType
 --type Shape' = Stream (Of ShapeObj) IO ()
 
 type Shape = [ShapeObj]