I make one quite big assumption. I approximate all properties across the face of a triangle as a linear combination of the vertex values. This means that velocity of the face is not accurate for large polygons that are rotating, but this can be solved simply with subdivision for these perhaps quite rare cases. Another consideration is that the force of the fluid is transfered to rigid bodies in a similar fashion for rigid body dynamics, and this could also lead to inaccuracies and perhaps instability.
The code is not in the best state, and there is still quite a bit of try and comment out code as well as out right hacks in there. The is already one regression. The plugin does not preserve state of object that are created after the physics plugin for example.
In order to catch regressions early, I was thinking of releasing regular snapshots that are simply totaly untested. If folks would like this it would mean that regressions would be picked up sooner rather than later. Otherwise the whole debug cycle gets a little slow. Let me know what you think.
So the next *proper* beta release (0.7) I will hopefully have the following fetures.
- Full polygon boundaries for moving and stationary objects.
- Basic Rigid body dynamics.
- Animating parameters.