prevent division by zero for non-ODE PushCutter operations

git-svn-id: https://pycam.svn.sourceforge.net/svnroot/pycam/trunk@219 bbaffbd6-741e-11dd-a85d-61de82d9cad9

pycam/Geometry/Point.py

@@ -2,36 +2,48 @@ import math
 
 class Point:
     id=0
+
     def __init__(self,x,y,z):
         self.id = Point.id
         Point.id += 1
         self.x = float(x)
         self.y = float(y)
         self.z = float(z)
+
     def __repr__(self):
         return "Point%d<%g,%g,%g>" % (self.id,self.x,self.y,self.z)
+
     def mul(self, c):
         return Point(self.x*c,self.y*c,self.z*c)
+
     def div(self, c):
         return Point(self.x/c,self.y/c,self.z/c)
+
     def add(p1, p2):
         return Point(p1.x+p2.x,p1.y+p2.y,p1.z+p2.z)
+
     def sub(p1, p2):
         return Point(p1.x-p2.x,p1.y-p2.y,p1.z-p2.z)
+
     def dot(p1, p2):
         return p1.x*p2.x + p1.y*p2.y + p1.z*p2.z
+
     def cross(p1, p2):
         return Point(p1.y*p2.z-p2.y*p1.z, p2.x*p1.z-p1.x*p2.z, p1.x*p2.y-p2.x*p1.y)
+
     def normsq(self):
         if not hasattr(self, "_normsq"):
             self._normsq = self.dot(self)
         return self._normsq
+
     def norm(self):
         if not hasattr(self, "_norm"):
             self._norm = math.sqrt(self.normsq())
         return self._norm
+
     def normalize(self):
         n = self.norm()
+        if n != 0:
             self.x /= n
             self.y /= n
             self.z /= n