"Global Momentum Preservation for Position-based Dynamics"

Position-based dynamics has emerged as an exceedingly popular approach for animating soft body dynamics. Unfortunately, the basic approach suffers from artificial loss of angular momentum. We propose a simple approach to preserve global linear and angular momenta of bodies by directly tracking these quantities and adjusting velocities to ensure they are preserved. This approach entails negligible computational cost, requires less than 25 lines of code, and exactly preserves global linear and angular momenta.

A. Dahl and A. W. Bargteil
"Global Momentum Preservation for Position-based Dynamics."
ACM SIGGRAPH Conference on Motion, Interaction and Games 2019

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