Allow tweaking z buffer when rendering polygon, improve explosion render

src/Polyhedra/Data.hs

@@ -5,6 +5,8 @@ module Polyhedra.Data
 import Geometry.Data
 
 import Control.Lens
+import qualified Data.Map as M
+--import qualified Data.IntSet as IS
 -- | Polyhedra are represented as a list of faces.
 -- Each face is a list of points (and colours) that are assumed to lie on a plane, and be
 -- ordered to form an anticlockwise convex polygon within that plane.
@@ -12,4 +14,14 @@ data Polyhedra = Polyhedron
     { _pyFaces :: [[(Point3,Point4)]]
     }
 
+-- | Describe a polygon as a map from vertex indices to a positiong and list of faces.
+-- The list of faces is assumed to be ordered in clockwise direction around the vertex.
+-- The vertices of the faces are assumed to start with a point adjacent to the
+-- key vertex and to be listed anticlockwise around the center of the face.
+-- The key vertex is not included in the list.
+data VF a = VF
+    { _vertices :: M.Map a (Point3, [[a]])
+    }
+
 makeLenses ''Polyhedra
+makeLenses ''VF