Add blurring of lightmap (and refactoring)

src/Dodge/Picture/Layer.hs

@@ -0,0 +1,40 @@
+{- |
+Uniform management of layers and depths on which pictures are drawn. -}
+module Dodge.Picture.Layer
+    ( onLayer
+    , onLayerL
+    , levLayer
+    , Layer (..)
+    ) where
+import Dodge.Picture.Layer.Data
+import Picture
+
+{- | Uses a layer to set the depth.
+ -}
+onLayer :: Layer -> Picture -> Picture
+onLayer l = setDepth $ 1 - fromIntegral (levLayer l) / 100
+
+{- | Set a depth according to a list of numbers.
+Lists are lexicographically ordered if input values are always less than 100.
+Higher numbers will get placed on top of lower numbers.
+-}
+onLayerL :: [Int] -> Picture -> Picture
+onLayerL is = setDepth (1 - (sum $ zipWith (/) (map fromIntegral is) $ map (100 **) [1..]))
+
+{- | For depth testing, set layer values.
+ -}
+levLayer :: Layer -> Int
+levLayer BgLayer            = 20
+levLayer PressPlateLayer    = 45
+levLayer CorpseLayer        = 50
+levLayer FlItLayer          = 55
+levLayer CrLayer            = 60
+levLayer WlLayer            = 74
+levLayer GloomLayer         = 67
+levLayer UPtLayer           = 70
+levLayer PtLayer            = 72
+levLayer HPtLayer           = 73
+levLayer ShadowLayer        = 75   
+levLayer LabelLayer         = 80
+levLayer InvLayer           = 85
+levLayer MenuDepth          = 90