[ODE] Trimesh problems

[Flavien Brebion]

Anders Olofsson wrote:

>I don't add any custom forces, I just have the gravity set. The loop 
>variable is just a safety thing so it wont hang on slow systems, it usually 
>loops 3-4 times on my system. FIXEDSTEP = 0.005 (200 hz).
>
>I'm going to write a little test.. Dropping a sphere on a triangle with the 
>normal (0,1,0) should result in the same motion as in dropping a sphere on 
>a plane with the same normal (0,1,0), right?! (With the same contact 
>parameters ofcourse)
>
>I dont understand how a sphere can start jumping higher and higher without 
>me adding some force, could it be somehow that the sphere sinks deeper 
>below a triangle sometimes and then the collision response act 
>accordingly?. Anyhow, I'll be back with the test result and I'll publish 
>out the source too.
>
>Thanks!
>  
>
A few things come to my mind:
1. What are the global ERP / CFM parameters set to ? Did you try to 
tweak them too ?
2. Make sure you're filtering out degenerated triangles in your 
trimeshes, because ODE isn't doing it, and last time it caused some 
severe bugs in my application.
3. My bet: in your video, you seem to have a pretty huge terrain. What 
scale units are you using ? Are the spheres dropped very far from the 
origin by any chance ? If so, i do think it's a float 32 precision 
problem, and you might verify this easily by switching ODE to double mode.

Cheers,

F. Brebion