VB Code:
  1. Dim Distance as Single
  2.  
  3. Distance = Sqr( (Obj1.x - Obj2.x)^2 + (Obj1.y - Obj2.y)^2 )
  4.  
  5. If Distance < Radius1 + Radius2 Then
  6.    'Collision!
  7. EndIf