Now correctly draws lasers behind and in front of mirrors. Phew.

robotgame/logic/lasermirror.py

@@ -157,28 +157,34 @@ def generate_lasers(playfield):
     Return [((x, y), direction), ...]
     """
     width, height = 16, 16
-    sources = ((pos, obj.direction) for pos, obj in filter(lambda posobj: isinstance(posobj[1], Source), playfield.items()))
+    sources = ((pos, obj.direction) for pos, obj
+               in filter(lambda posobj: isinstance(posobj[1], Source),
+                         playfield.items()))
     lasers = []
+    def add(start, end):
+        t = (min(start, end), max(start, end))
+        if not t in lasers:
+            lasers.append(t)
     for start, direc in sources:
         end = start
         while True:
             cur = playfield.get(end)
             if cur is Target:
-                lasers.append(((start, end), direc))
+                add(start, end)
                 break
             if cur is Blocker:
-                lasers.append(((start, end), direc))
+                add(start, end)
                 break
             if cur in (MirrorLeft, MirrorRight):
                 if (start, end) in ((start, end) for (start, end), direc in lasers):
                     break
-                lasers.append(((start, end), direc))
+                add(start, end)
                 direc = _mirror_new_direc(cur, direc)
                 start = end
             new_end = direc.next_pos(end)
-            if new_end[0] < 0 or new_end[1] < 0 or new_end[0] >= width or new_end[1] >= height:
-                if (start, end) not in lasers:
-                    lasers.append(((start, new_end), direc))
+            if new_end[0] < 0 or new_end[1] < 0 or \
+                    new_end[0] >= width or new_end[1] >= height:
+                add(start, new_end)
                 break
             end = new_end
     return lasers