Reactor is a method or pattern for making an object respond to the proximity of another object. The controller object could be a single point such as the mouse location, or many controller objects could be used simultaneously such as fingers tracked with leap or Kinect.
Geometric shapes or splines can be divided into their constituting points, and those points used as the reactor for more complex forms and arrangements.
This simple method can result in complex organic forms, with many possibilities for the transformation in the reacting object such as rotation, scale, colour, substitution or more complex deformations.