Trimesh-trimesh collider (was Re[2]: [ODE] Triangle-box collidercontribution)

[Jeffrey Smith]

Jon Watte
> Honestly, I don't think current consumer machines are likely to work
> well with a variety of objects each creating 128 contacts, 2,000
> times a second. A typical high-rate game uses a step size of 10
> milliseconds, and a typical network-rate game, 33 ms.

Well, those were just values from a scene that I had handy. In
practice, I can get by with timesteps much larger than that.
Similarly, I use a big contact array because arbitrary trimesh objects
can create lots of contacts. In practice, I usually get 10-20 contacts
back from dCollide, and even fewer after I do some combining of
similar contacts.

> A typical consumer PC in use today has about 1.2 GHz of CPU power --
> unfortunately, half of that goes to graphics tranform

The alternative to my heuristic stuff is a true GJK technique which
can be even MORE expensive (certainly in terms of start-up costs
for each object).  You will pay either way if you want exact
trimesh collisions.

Also, I'm using ODE within Softimage XSI, a high-end animation tool.
Computation time is not as big a deal for us as it is for games;
consequently I haven't placed much importance on fast computation time
in my work.  I leave it as an "exercize for the reader" to improve
its performance.


-jeff