fix circumcircle

git-svn-id: https://pycam.svn.sourceforge.net/svnroot/pycam/trunk@76 bbaffbd6-741e-11dd-a85d-61de82d9cad9

pycam/Geometry/Triangle.py

@@ -125,9 +125,9 @@ class Triangle:
     def normal(self):
         if self._normal is None:
             # calculate normal, if p1-p2-pe are in clockwise order
-            self._normal = self.p3.sub(self.p1).cross(self.p2.sub(self.p1))
-            denom = self._normal.norm()
-            self._normal = self._normal.div(denom)
+            n = self.p3.sub(self.p1).cross(self.p2.sub(self.p1))
+            n.normalize()
+            self._normal = n
         return self._normal
 
     def plane(self):
@@ -211,12 +211,19 @@ class Triangle:
         return self._radiussq
 
     def calc_circumcircle(self):
-        normal = self.normal()
-        self._radius = (self.p2.sub(self.p1).norm()*self.p3.sub(self.p2).norm()*self.p3.sub(self.p1).norm())/(2)
+        # we can't use the cached value of "normal", since we don't want the normalized value
+        normal = self.p2.sub(self.p1).cross(self.p3.sub(self.p2))
+        print "normal=",normal
+        denom = normal.norm()
+        print "denom=",denom
+        self._radius = (self.p2.sub(self.p1).norm()*self.p3.sub(self.p2).norm()*self.p3.sub(self.p1).norm())/(2*denom)
+        print "radius=",self._radius
         self._radiussq = self._radius*self._radius
-        alpha = self.p3.sub(self.p2).normsq()*(self.p1.sub(self.p2).dot(self.p1.sub(self.p3))) / 2
-        beta  = self.p1.sub(self.p3).normsq()*(self.p2.sub(self.p1).dot(self.p2.sub(self.p3))) / 2
-        gamma = self.p1.sub(self.p2).normsq()*(self.p3.sub(self.p1).dot(self.p3.sub(self.p2))) / 2
+        denom2 = 2*denom*denom
+        alpha = self.p3.sub(self.p2).normsq()*(self.p1.sub(self.p2).dot(self.p1.sub(self.p3))) / (denom2)
+        beta  = self.p1.sub(self.p3).normsq()*(self.p2.sub(self.p1).dot(self.p2.sub(self.p3))) / (denom2)
+        gamma = self.p1.sub(self.p2).normsq()*(self.p3.sub(self.p1).dot(self.p3.sub(self.p2))) / (denom2)
+        print "alpha=",alpha,", beta=",beta,", gamma=",gamma
         self._middle = Point(self.p1.x*alpha+self.p2.x*beta+self.p3.x*gamma,
                              self.p1.y*alpha+self.p2.y*beta+self.p3.y*gamma,
                              self.p1.z*alpha+self.p2.z*beta+self.p3.z*gamma)