Allow drawing the polygon stuff via GUI

Parser/Meshparser.hs

@@ -1,28 +1,42 @@
 {-# OPTIONS_HADDOCK ignore-exports #-}
 
-module Parser.Meshparser (meshToArr) where
+module Parser.Meshparser (meshToArr, facesToArr) where
 
 import Algebra.VectorTypes
 import Control.Applicative
+import Data.Maybe
 import Diagrams.TwoD.Types
 import Parser.Core
 
 
--- | Convert a text String with multiple vertices into
+-- |Convert a text String with multiple vertices and faces into
+-- a list of vertices, ordered by the faces specification.
+facesToArr :: String -> [[PT]]
+facesToArr str = fmap (fmap (\y -> meshs str !! (fromIntegral y - 1)))
+                      (faces str)
+  where
+    meshs = meshToArr
+    faces = fmap fst . catMaybes . fmap (runParser parseFace) . lines
+
+
+-- |Convert a text String with multiple vertices into
 -- an array of float tuples.
 meshToArr :: String   -- ^ the string to convert
           -> [PT]     -- ^ the resulting vertice table
 meshToArr =
-  fmap p2                         .
-    fmap (\(Just (x, _)) -> x)    .
-    filter (/= Nothing)           .
-    fmap (runParser parseVertice) .
-    lines
+  fmap (p2 . fst)
+    . catMaybes
+    . fmap (runParser parseVertice)
+    . lines
 
 
--- | Creates a Parser that accepts a single vertice, such as 'v 1.0 2.0'.
+-- |Creates a Parser that accepts a single vertice, such as 'v 1.0 2.0'.
 parseVertice :: Parser (Double, Double)
 parseVertice =
-  (,)                                 <$>
-    (char 'v' *> spaces *> allDouble) <*>
-    (spaces *> allDouble)
+  (,)
+    <$> (char 'v' *> spaces *> allDouble)
+    <*> (spaces *> allDouble)
+
+
+parseFace :: Parser [Integer]
+parseFace = char 'f' *> oneOrMore (spaces *> posInt)