Rolling box "sucked" through mesh terrain; video example!

[phr00t]

Hey guys,

I'm working on a physics bug in 3089... whenever a box gets rolling on a hill, it will often just get "sucked" through the ground. It isn't just falling through, it picks up amazing speed to pop through the other side underground. Here is an example video:

http://www.youtube.com/watch?v=ltSdp0qif_k

I've set the grounds margin to 0.075 (and even all the way up to 1), and although it causes the box to "float" a bit above the terrain, it still falls through at certain rolling speeds and angles like in the video. The default margin of 0 also causes the problem.

The box is a simple BoxCollisionShape and the ground is a MeshCollisionShape (in jMonkeyEngine), using the official release native 2.82 Bullet build. The friction on the box is 3. Setting it to 0.5 or lower makes it slide around and roll less, which seems to make it want to get sucked through the ground slightly less, but it still happens...

EDIT: Sphere-shaped objects and raytests don't seem to have any problem on areas where the box fall through...

Anyone see this before and/or have any suggestions? Thank you!

[phr00t]

For anyone else who has this problem, I "solved" it by modeling my boxes as 9 spheres: 1 big one for the center of the box, and 8 smaller ones for the corners. I had to do this since I just couldn't get boxes (or other shapes with sharp edges) to work. Spheres FTW (as in, "for the workaround")!

[slithEToves]

I don't know if you are still having a problem with this, but there is a similar issue here with a new solution:

http://bulletphysics.org/Bullet/phpBB3/ ... f=9&t=9100