   compute 3d reflection
  Does somebody know how to compute the 3d reflection matrix given 2 edges that we know that have been mirrored?I think I solved for rotation and translation: I dot to have the angle, I cross to have the rotation axe and subtract to have the translation.What about the reflection?Thanks.   
  If A is a point and B is its reflection through a to-be-determined plane, then the difference B-A is perpendicular to the plane and the average (B+A)/2 is a point on the plane.  That is, if N = (B-A)/Length(B-A) and P = (B+A)/2, the plane is Dot(N,X-P) = 0.  (Of course, you need to worry when A = B...)If Y is any point, then Reflection(Y) = Y - 2*Dot(N,Y-P)N.  In affine form, this is Reflection(Y) - P = (I - N*Transpose(N))*(Y - P).   