X-Git-Url: https://git.yukkurigames.com/?p=python-bulletml.git;a=blobdiff_plain;f=bulletml%2Fimpl.py;h=9a1aa56adda6b9fc69727a34bdd72668f63e16eb;hp=938e9e23ad85567a7a38c5a55d385af6cf5ba70f;hb=978a7d7372a25f5d2e5d4401151e20fd913bdae0;hpb=5da55ac7eeae21ee0ca3149bed99c95383397f05

diff --git a/bulletml/impl.py b/bulletml/impl.py
index 938e9e2..9a1aa56 100644
--- a/bulletml/impl.py
+++ b/bulletml/impl.py
@@ -284,7 +284,7 @@ class Bullet(object):
     Contructor Arguments:
     x, y, direction, speed, target, rank - same as the attributes
     actions - internal action list
-    parent - parent of actions, None for manually-created bullets
+    Action - custom Action constructor
 
 
     """
@@ -305,6 +305,13 @@ class Bullet(object):
         self._actions = [Action(self, None, action, params, rank)
                          for action, params in actions]
 
+    @classmethod
+    def FromDocument(cls, doc, x=0, y=0, direction=0, speed=0, target=None,
+                     params=(), rank=0.5, Action=Action):
+        """Construct a new Bullet from a loaded BulletML document."""
+        actions = [a(params, rank) for a in doc.actions]
+        return cls(x, y, direction, speed, target, actions, rank, Action)
+
     def __repr__(self):
         return ("%s(%r, %r, accel=%r, direction=%r, speed=%r, "
                 "actions=%r, target=%r, vanished=%r)") % (
@@ -314,11 +321,17 @@ class Bullet(object):
 
     @property
     def aim(self):
-        """Angle to the target, in radians."""
-        if self.target is None:
-            return self.direction
+        """Angle to the target, in radians.
+
+        If the target does not exist or cannot be found, return 0.
+        """
+        try:
+            target_x = self.target.x
+            target_y = self.target.y
+        except AttributeError:
+            return 0
         else:
-            return math.atan2(self.target.x - self.x, self.y - self.target.y)
+            return math.atan2(target_x - self.x, self.y - target_y)
 
     @property
     def finished(self):