Search found 198 matches

by Dragonlord
Wed Feb 23, 2022 8:40 pm
Forum: General Bullet Physics Support and Feedback
Topic: Improving stacking stability
Replies: 1
Views: 6629

Re: Improving stacking stability

I checked with debug drawing and the 5-can stack sometimes deactivates while the 10-can pyramid does not deactivate. After some time the active stack tends to fall apart. So if I could increase the deactivation conditions I could improve these cases. Personally I think for a game it is better to hav...
by Dragonlord
Wed Feb 23, 2022 7:29 pm
Forum: General Bullet Physics Support and Feedback
Topic: Improving stacking stability
Replies: 1
Views: 6629

Improving stacking stability

I'm trying to improve the physics simulation of bullet. I have a simple test case: https://upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Dosenwerfen_2008_035.jpg/330px-Dosenwerfen_2008_035.jpg Furthermore I have 5 cans on the ground stacked on top of each other in a straight pillar each exactly ...
by Dragonlord
Wed Feb 23, 2022 3:05 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unstable behavior on shapes like cylinder or box
Replies: 11
Views: 74927

Re: Unstable behavior on shapes like cylinder or box

It seems to use rolling friction you need to also enable anisotropic rolling friction. Doing so makes the rolling friction work without objects standing on the edges that much. There is still some angles at which they stand still but I'll go through the bullet examples and collect the parameters use...
by Dragonlord
Wed Feb 23, 2022 12:56 am
Forum: General Bullet Physics Support and Feedback
Topic: Unstable behavior on shapes like cylinder or box
Replies: 11
Views: 74927

Re: Unstable behavior on shapes like cylinder or box

I've done some more experimenting and disabled this and that rigid body option until I got a change. It looks like the rolling friction cause the problem. I used the value from the RollingFrictionDemo which is 0.1f . Using this value the cylinder does not roll but can even stand on its edge at 80 de...
by Dragonlord
Tue Feb 22, 2022 9:46 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unstable behavior on shapes like cylinder or box
Replies: 11
Views: 74927

Re: Unstable behavior on shapes like cylinder or box

Ok that debpMotionState looks fine: I don't see any misbehaving logic there. Any ideas where I could put a lever to debug this problem? I tried examining the contact constraint generated but I did not get the impression something is wrong. That said I'm not much into physics coding so I don't know ...
by Dragonlord
Tue Feb 22, 2022 5:14 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unstable behavior on shapes like cylinder or box
Replies: 11
Views: 74927

Re: Unstable behavior on shapes like cylinder or box

The beer can... when it lands on the ground does it get deactivated? or does it remain active? Are you using a custom MotionState in your game? If so, what does its getWorldTransform() and setWorldTransform() implementations look like? Yes, a motion state is used. The code is here: https://github.c...
by Dragonlord
Tue Feb 22, 2022 12:03 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unstable behavior on shapes like cylinder or box
Replies: 11
Views: 74927

Re: Unstable behavior on shapes like cylinder or box

The box and cylinder shapes are not unstable. I've seen them work fine. I don't know what is wrong with your beer can. It behaves as if... the moment it hits the ground its world-frame inverse inertia tensor gets zero elements in the two axes perpendicular to the UP direction. That is: it is constr...
by Dragonlord
Mon Feb 21, 2022 4:07 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unstable behavior on shapes like cylinder or box
Replies: 11
Views: 74927

Re: Unstable behavior on shapes like cylinder or box

I've added a small video showing the problem.
screencap.gif
screencap.gif (2.32 MiB) Viewed 74865 times
by Dragonlord
Mon Feb 21, 2022 2:51 am
Forum: General Bullet Physics Support and Feedback
Topic: Unstable behavior on shapes like cylinder or box
Replies: 11
Views: 74927

Unstable behavior on shapes like cylinder or box

I'm trying to tackler issues in the bullet integration. I've got two main issues I can't find a solution for. Maybe somebody has seen them before and knows in what direction to look for the problem? The first is a strange behavior of cylinder and box shapes. For example I've got a can (beer can, pic...
by Dragonlord
Sun Jan 19, 2020 7:25 pm
Forum: General Bullet Physics Support and Feedback
Topic: Getting Stuck issues with convexSweepTest
Replies: 0
Views: 6451

Getting Stuck issues with convexSweepTest

I'm reading things up for a release soon and one problem started to show up when I used convexSweepTest instead if my own collision tests. This is for kinematic collision hence no physics involved (think human actor movement). If actors hit a wall bullet runs into a getting-stuck situation. The firs...
by Dragonlord
Thu Jul 27, 2017 8:21 pm
Forum: General Bullet Physics Support and Feedback
Topic: Generic6DOF joint friction bugged (with example)
Replies: 5
Views: 12829

Re: Generic6DOF joint friction bugged (with example)

I've setup another example with the kinematic joint friction case. Bullet is definitely bugged since it is unable to counter gravity using a motor even if the force is set ridiculously high. The atteched example shows the problem. If nobody is going to take a look at this problem I'm going to throw ...
by Dragonlord
Mon Jul 24, 2017 2:34 pm
Forum: General Bullet Physics Support and Feedback
Topic: Generic6DOF joint friction bugged (with example)
Replies: 5
Views: 12829

Re: Generic6DOF constraint cancel force problem

I tried putting together a test case in ExampleBrowser (getting this to work is a real pain). The attached file is the first part of the problem, the one with the constraint doing strange things right at the start. In my real test case this also leads to strange jittering but I could not directly re...
by Dragonlord
Thu Jul 20, 2017 10:49 pm
Forum: General Bullet Physics Support and Feedback
Topic: Generic6DOF joint friction bugged (with example)
Replies: 5
Views: 12829

Re: Generic6DOF constraint cancel force problem

I did some more testings and after running into a strange problem where the first step produces a linear velocity that should not be there I have the suspicion Bullet is bugged. Can somebody confirm this behavior to be wrong? // before doing simulation step (showing state after last simulation step)...
by Dragonlord
Tue Jul 18, 2017 5:16 pm
Forum: General Bullet Physics Support and Feedback
Topic: Generic6DOF joint friction bugged (with example)
Replies: 5
Views: 12829

Re: Generic6DOF constraint cancel force problem

That's not the final goal. This is just a step in between to get it working. What I want in the end is inner joint friction, hence the joint resisting to be moved along the limited degree of freedom, like a rusty hinge on a door.
by Dragonlord
Sun Jul 16, 2017 10:37 pm
Forum: General Bullet Physics Support and Feedback
Topic: Generic6DOF joint friction bugged (with example)
Replies: 5
Views: 12829

Generic6DOF joint friction bugged (with example)

I try to setup a linear motor on a generic 6dof constraint subclass with the simple task of cancelling all forces to keep a platform (no angular movement, only linear up-down movement possible) at a steady altitude. It's a preparation for more but I can't even get this simple problem working. I do t...