Add wall drawing capability (for shadows)

src/Dodge/Rendering.hs

@@ -508,6 +508,18 @@ wallsForGloom w = map (\(x:y:_) -> (screenShift x,screenShift y)) $
     where screenShift x = zoom *.* rotateV (0 - _cameraRot w) (x -.- _cameraPos w)
           zoom = _cameraZoom w
 
+wallsForGloom' :: World -> [(Point2,Point2,Point2,Point2)]
+wallsForGloom' w = map (wallPairToFour . _wlLine) $ filter (not . _wlIsSeeThrough) 
+                                $ IM.elems $ wallsNearZones (zoneOfDoubleScreen w) w
+
+    where wallPairToFour (x:y:_) = (ss x,ss y,ss $ x +.+ n,ss $ y+.+ n)
+            where n = 20 *.* (normalizeV $ vNormal $ y -.- x)
+          ss' v = rotateV (0 - _cameraRot w) (v -.- _cameraPos w)
+          ss'' (a,b) = (a*2*zoom / _windowX w,b*2*zoom / _windowY w)
+          ss = ss'' . ss'
+-- the ss transformation would possibly be better done using a matrix in the
+-- shader
+          zoom = _cameraZoom w
 
 lightsForGloom :: World -> [(Point2,Float,Float)]
 lightsForGloom w = map getLS (IM.elems $ _lightSources w) ++ map getTLS (_tempLightSources w)