guard against float division

git-svn-id: https://pycam.svn.sourceforge.net/svnroot/pycam/trunk@22 bbaffbd6-741e-11dd-a85d-61de82d9cad9

pycam/Geometry/intersection.py

@@ -16,6 +16,7 @@ def intersect_lines(xl,zl,nxl,nzl,xm,zm,nxm,nzm):
     X = None
     Z = None
 #    print "xl=",xl,", zl=",zl,"nxl=",nxl,", nzl=",nzl,", X=", X, ", Z=",Z,", xm=",xm,",zm=",zm, ", nxm=",nxm,",nzm=",nzm
+    try:
         if isZero(nzl) and isZero(nzm):
             pass
         elif isZero(nzl) or isZero(nxl):
@@ -27,14 +28,12 @@ def intersect_lines(xl,zl,nxl,nzl,xm,zm,nxm,nzm):
             Z = zl - (xm-xl)*nxl/nzl
             return (X,Z)
         else:
-        try:
             X = (zl-zm+(xm*nxm/nzm-xl*nxl/nzl))/(nxm/nzm-nxl/nzl)
-        except:
-            pass
-
             if X and xl < X and X < xm:
                 Z = zl + (X-xl)*nxl/nzl
                 return (X,Z)
+    except:
+        pass
     return (None,None)
 
 def intersect_plane_point(plane, direction, point):