Oh that's interesting because I would have assumed the demoscene stuff would have done some kind of direct signed distance field rendering and skipped the marching cubes part.

And yea I remember the patent being in effect for so many years. The Spore creators got around it by using the "ear clipping" algorithm.

Negative Metaballs are really fun — included them in our app I mentioned at the end of the video. But they date all the way back to Blinn's paper!