It is nearly impossible to, in real life, spin a pencil fast enough to keep it from falling over. But this simulated cylinder does stay up for a while with only a gentile spin. YES I remembered to do alt+r and ctrl+a after scaling the object. I know it's a LOT bigger than a pencil, but even an object this size shouldn't behave this way.
heres the blend: http://uploader.polorix.net//files/52/unrealistic.blend
Long thin objects are very unrealistic
-
- Site Admin
- Posts: 4221
- Joined: Sun Jun 26, 2005 6:43 pm
- Location: California, USA
Bullet favors stability over realism.Gyroscopic (Coriolis, velocity dependent) forces are not modeled at the moment.
This is added to the Physics Tips:
http://www.continuousphysics.com/mediaw ... ysics_Tips
Bullet might improve in this area, in the future.
Thanks for the feedback,
Erwin
This is added to the Physics Tips:
http://www.continuousphysics.com/mediaw ... ysics_Tips
Bullet might improve in this area, in the future.
Thanks for the feedback,
Erwin
-
- Posts: 16
- Joined: Tue Jan 02, 2007 1:57 am
-
- Posts: 231
- Joined: Tue Feb 20, 2007 4:56 pm
-
- Posts: 16
- Joined: Tue Jan 02, 2007 1:57 am
-
- Posts: 16
- Joined: Tue Jan 02, 2007 1:57 am
This is a semifinal version, I promised it today, and I'll "publish" the final tomorrow. I'm pretty sure this works, me and my father used the file from Blender 2.43. If you have any trouble PM me right away.
http://uploader.polorix.net//files/52/btRigidBody.cpp
Just replace the CPP file in src\BulletDynamics\Dynamics with this.
The final will include a build (2.43, I can't compile 2.44), this file with descriptive comments, and a .blend with accurate physics baked into IPO for several examples.
Since humans don't usually see objects tumble freely for 10 seconds, at first glance some of the motions may appear a bit unrealistic, but it has held up to my most brutal physics tests.
Note: It doesn't merely estimate the precession, it uses a stable, robust RK4 model that works in any case (long thin, short fat, bricks, free rotation, touching ground, etc.).
I don't quite know how much this precession fix slows down the speed, but it is a small change, especially small for large scenes with high collision count.
I wanted to PM Erwin but couldn't.
http://uploader.polorix.net//files/52/btRigidBody.cpp
Just replace the CPP file in src\BulletDynamics\Dynamics with this.
The final will include a build (2.43, I can't compile 2.44), this file with descriptive comments, and a .blend with accurate physics baked into IPO for several examples.
Since humans don't usually see objects tumble freely for 10 seconds, at first glance some of the motions may appear a bit unrealistic, but it has held up to my most brutal physics tests.
Note: It doesn't merely estimate the precession, it uses a stable, robust RK4 model that works in any case (long thin, short fat, bricks, free rotation, touching ground, etc.).
I don't quite know how much this precession fix slows down the speed, but it is a small change, especially small for large scenes with high collision count.
I wanted to PM Erwin but couldn't.
-
- Posts: 16
- Joined: Tue Jan 02, 2007 1:57 am
Final Version:
http://www.graphicall.org/builds/builds ... how&id=451
It's very stable and accurate physics, with a negligible simulation speed slow-down.
http://www.graphicall.org/builds/builds ... how&id=451
It's very stable and accurate physics, with a negligible simulation speed slow-down.