Physics (was Re: [Bf-committers] Manic MSVC blender compile s ession)

Laurence Bourn
Thu, 7 Nov 2002 15:01:39 +0100

> The issue for me is that I simply don't know how compatible 
> ODE is with
> the Sumo (current physics system), because I have very little 
> experience
> using, much less coding with, Sumo. It is possible that ODE 
> can be made
> compatible with the old physics; I simply do not know. Ex-NaN 
> engineers
> who worked on the physics code would be able to give more 
> insight on this
> than I.

From my point of view sumo physics was a very immature system. State of the
art collision detection but the collision response stuff was poor (but
nicely coded). Users often had to set totally wacky friction and
restituition levels etc to get the affect they wanted (which interestingly
did not seem to be realistic simulation but super mario style physics (Ton
will tell you all about this...). The truth is that Sumo was always quite
poor, the only dynamic objects supported are spheres, friction does not work
right, does not deal well with fast moving objects, objects pass through
walls even at low speeds [they somehow squeeze between the molecules was one
artisits comment if I remember]. 

The only reason people used was that its the only option. In fact many of
our inhouse artists by passed it totally and wrote their own physics in
Python. It does nothing particularly well. My opinion is SCRAP IT. People
who wrote the old game blender files will probably just be please that at
last there is a decent alternative (ODE). 

That just leaves the collision detection code. Of course it would be great
to have access to Gino's latest SOLID 3, realistically we can choose between
SOLID 2.0 and ODE's existing solution. I would go for the latter, coz I
can't see anyone evolving SOLID 2.0 and ODE's is better.  

> To summarize: (1) using ODE collision and ODE physics results 
> in better
> rigid body dynamics but possibly incompatibility with earlier Blender
> files. (2) Using SOLID 2.0 collision enhanced with ODE 
> collision, and Sumo
> physics will probably result in phyics which is mostly-compatible with
> the previous implementation.
> It would be interesting if any ex-NaN engineers could comment 
> on each of
> these two alternatives.

OPTION 1 gets my vote.