Check facing.

airpower/aircraft.py

@@ -1,6 +1,7 @@
-import airpower.draw     as apdraw
 import airpower.altitude as apaltitude
 import airpower.azimuth  as apazimuth
+import airpower.draw     as apdraw
+import airpower.hex      as aphex
 import airpower.hexcode  as aphexcode
 
 import math
@@ -9,13 +10,17 @@ class Aircraft:
 
   def __init__(self, name, hexcode, azimuth, altitude):
 
+    x, y = aphexcode.toxy(hexcode)
+    facing = apazimuth.tofacing(azimuth)
+
     apaltitude._checkaltitude(altitude)
+    aphex.checkisvalidfacing(x, y, facing)
 
     self._turn          = 0
     self._name          = name
-
-    self._x, self._y    = aphexcode.toxy(hexcode)
-    self._facing        = apazimuth.tofacing(azimuth)
+    self._x             = x
+    self._y             = y
+    self._facing        = facing
     self._altitude      = altitude
     self._altitudecarry = 0
     self._destroyed     = False
@@ -350,6 +355,9 @@ def next(self, actions):
         break
 
     assert self._ifp <= self._nfp
+    aphex.checkiscenteroredge(self._x, self._y)
+    aphex.checkisvalidfacing(self._x, self._y, self._facing)
+    apaltitude._checkaltitude(self._altitude)
 
     if self._ifp == self._nfp:
 

airpower/hex.py

@@ -59,8 +59,43 @@ def checkiscenteroredge(x, y):
 
   """
   Raise a ValueError exception if the point (x,y) in hex coordinates does not 
-  correspond to the center of a hex or to (the center of) the edge of a hex
+  correspond to the center of a hex or to (the center of) the edge of a hex.
   """
 
   if not iscenteroredge(x, y):
     raise ValueError("(%s,%s) is not the center or edge of a hex." % (x,y))
+
+def isvalidfacing(x, y, facing):
+
+  """
+  Return True if facing is a valid facing at the point (x, y) in hex 
+  coordinates, which must correspond to to the center of a hex or to (the 
+  center of) the edge of a hex.
+  """
+
+  checkiscenteroredge(x, y)
+
+  if iscenter(x, y):
+    return facing % 30 == 0
+
+  if x % 2 == 0.5 and y % 1.0 == 0.25:
+    return facing % 180 == 120
+  elif x % 2 == 0.5 and y % 1.0 == 0.75:
+    return facing % 180 == 60
+  elif x % 2 == 1.0 and y % 1 == 0.25:
+    return facing % 180 == 60
+  elif x % 2 == 1.0 and y % 1.0 == 0.75:
+    return facing % 180 == 120
+  else:
+    return facing % 180 == 0
+
+def checkisvalidfacing(x, y, facing):
+
+  """
+  Raise a ValueError exception if facing is not a valid facing at the point 
+  (x, y) in hex coordinates, which must correspond to to the center of a hex or 
+  to (the center of) the edge of a hex.
+  """
+
+  if not isvalidfacing(x, y, facing):
+    raise ValueError("(%s,%s) is not the center or edge of a hex." % (x,y))