OpenTissue is a meta-engine library for physics-based animation and simulation.
Free for commercial use, open source under the ZLib License.

Instructions on how to obtain OpenTissue can be found at

  http://www.opentissue.org/

Installation instructions, Programming Guide Lines, and Toturials can be found
at the OpenTissue WikiPage

  http://opentissue.org/wikitissue/index.php/Main_Page

Disucssions and Questions can be found at the OpenTissue Forum

  http://www.opentissue.org/opentissuebb/

Library documentation may be found in the documentation sub-folder of ones
OpenTissue installation.