Okay, now my brain is fried. Just spent way too long looking through legal garbage for an answer. However, looking through U.S. copyright law I found this page relating to derivative works: http://www.copyright.gov/circs/circ14.html I would have thought that if you tweaked a formula enough to produce something completely different, you would be okay. But according to this statement, it would probably be best to contact the author first: "Only the owner of copyright in a work has the right to prepare, or to authorize someone else to create, a new version of that work." Also, just because it is offered as a free download, does not mean it is in the public domain and free to be changed. Hope this helps. Nick

Nick C. Sorbin
Staff Writer
Renderosity Magazine
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"For every breath, for every day of living, this is my Thanksgiving."
-Don Henley