  <hr> The program blobby.net computes an implicit surface based on spherical fields of influence which can add together. See one of last year's  <a href="http://www.tc.cornell.edu/Visualization/contrib/cs490-94to95/shuang/bm.html"> student projects </a> for more information on blobby functions. The spherical fields can have positive and negative field strengths. An example from  blobby.net shows four positive spheres (transparent red) and two negative spheres (blue) which when summed together, then passed thorough an isosurface module produce the object shown to the right. <p>
