"As with the shader trees, a third party technology, which unless cash-strapped CL found the initial finance to buy up front, rather than paying a fee per unit shipped" every cloth engine is licensed. Maya's is licensed from the original researchers andy witkin, and david baraff. likewise with other cloth that has popped up (with the exception of a few that are sold as external plug-ins). this is just like the other technology roalties that are paid to various researchers (like the z-buffer which was created by Ed Catmull). I know there's been an effort to portray p5 as a "frankenstein" program, but if that's true then it's true of most other apps in the industry. You like Rhino? the nurbs libraries are licensed from the same company that Alias licenses them from (they might even be licensed from Alias). Maya licenses it's tech from various other research companies as well. In addition, in programs like Rhino, and Maya, the actual engine's are just a small part of the program, and don't even deal with the most basic building blocks like data structures, etc.