Search found 74 matches

by SynapticBytes
Wed Feb 06, 2013 8:26 am
Forum: General Bullet Physics Support and Feedback
Topic: Softbody motion issues
Replies: 20
Views: 18770

Re: Softbody motion issues

Right well, here I am back again. Reducing clusters works well for simple shapes, but as soon as I throw a complex mesh at it, we're back to major struggles trying to stop it wandering off randomly. A cluster size of 1 is the only thing that has stopped my bigger mesh, and that's unacceptable as it ...
by SynapticBytes
Mon Feb 04, 2013 8:26 pm
Forum: General Bullet Physics Support and Feedback
Topic: Softbody motion issues
Replies: 20
Views: 18770

Re: Softbody motion issues

Well I have finally had a bit more luck, after finding this post. http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=6664&view=previous Seems I'm not the only one who has experienced these issues, and just changing the number of clusters to a small value (3 - 5 seems to work for my s...
by SynapticBytes
Mon Feb 04, 2013 9:20 am
Forum: General Bullet Physics Support and Feedback
Topic: How to set the axis of btSliderConstraint?
Replies: 3
Views: 3373

Re: How to set the axis of btSliderConstraint?

Something like this

Code: Select all

btTransform tr = new btTransform;
tr.setIdentity();
tr.setOrigin(btVector3(0,1,0)); // whatever vector values you want for your translation axis
by SynapticBytes
Mon Feb 04, 2013 3:48 am
Forum: General Bullet Physics Support and Feedback
Topic: Softbody motion issues
Replies: 20
Views: 18770

Re: Matching softbodies to 3D objects - no motionstate?

You know what, after studying the running SoftDemo in a bit more detail, I think it actually exhibits the same behaviour, it's just hard to see as there is very little stillness in the demo's. The single torus or the bunnies sits on a flat plane and looks motionless, but after 5 minutes of running, ...
by SynapticBytes
Mon Feb 04, 2013 12:12 am
Forum: General Bullet Physics Support and Feedback
Topic: Softbody motion issues
Replies: 20
Views: 18770

Re: Matching softbodies to 3D objects - no motionstate?

I had tried all the solver iteration paramaters yesterday, varying them from 0, 1 -> 20. No real difference except velocity, and raising it made my body fall through the plane. I've spent all last night stripping my code to use the SoftDemo code. The fact there seems to be bugs in the SoftDemo sourc...
by SynapticBytes
Sun Feb 03, 2013 4:14 am
Forum: General Bullet Physics Support and Feedback
Topic: Softbody motion issues
Replies: 20
Views: 18770

Re: Matching softbodies to 3D objects - no motionstate?

*sigh* no joy 1. Changed to 1/120th step, no difference 2. Added another dropped rigid body cylinder, same height and size as the softbody cylinder. It drops and sticks flat, as it should. I also went through and disabled my simulation tick callback, my graphic model updating and anything else that ...
by SynapticBytes
Sun Feb 03, 2013 2:17 am
Forum: General Bullet Physics Support and Feedback
Topic: Softbody motion issues
Replies: 20
Views: 18770

Re: Matching softbodies to 3D objects - no motionstate?

That is much more rigid than I had anticipated. Also that looks like normal jitter when there is one minor thing misconfigured. For the sake of thoroughness, lets run down the list. 1. Scale. How large or small are these objects? Depending on their size and the timestep, too much time may be passin...
by SynapticBytes
Sun Feb 03, 2013 1:02 am
Forum: General Bullet Physics Support and Feedback
Topic: Softbody motion issues
Replies: 20
Views: 18770

Re: Matching softbodies to 3D objects - no motionstate?

Still no luck removing the jiggles. I've put a youtube video up showing what's happening, although it's my first Youtube video, and the quality is pretty bad, sorry about that. Debug drawing of wireframe is on. Hopefully you can at least get the idea of what the body is doing. *EDIT* slightly improv...
by SynapticBytes
Sat Feb 02, 2013 9:31 pm
Forum: General Bullet Physics Support and Feedback
Topic: Softbody motion issues
Replies: 20
Views: 18770

Re: Matching softbodies to 3D objects - no motionstate?

Thanks that list will be good. I didn't realise the triangles were already collision shapes. Other posts I'd read said only the vertices collided, causing penetration when triangles are large. I thought that was what clusters prevented, even on 1 cluster per triangle. But i guess that's why I didn't...
by SynapticBytes
Sat Feb 02, 2013 8:22 pm
Forum: General Bullet Physics Support and Feedback
Topic: Destruction of compound object
Replies: 1
Views: 3170

Re: Destruction of compound object

This probably isn't the effect you're looking for, but using constraints between your cubes and using a constraint breaking threshold should make it break apart on impact. Otherwise as you say, detect collision then remove the colliding cube, and maybe then add another downward impulse to force the ...
by SynapticBytes
Sat Feb 02, 2013 8:18 pm
Forum: General Bullet Physics Support and Feedback
Topic: How to set the axis of btSliderConstraint?
Replies: 3
Views: 3373

Re: How to set the axis of btSliderConstraint?

When setting up the slider, you pass in a tranform which contains the translation axis. So just set your axis vector in that transform.
by SynapticBytes
Sat Feb 02, 2013 8:03 pm
Forum: General Bullet Physics Support and Feedback
Topic: Softbody motion issues
Replies: 20
Views: 18770

Re: Matching softbodies to 3D objects - no motionstate?

Right, so I did a little more research on clusters, and it seems you're right on what clusters do, but using 0 as a parameter creates a cluster for each triangle. From the api generateClusters with k=0 will create a convex cluster for each tetrahedron or triangle otherwise an approximation will be u...
by SynapticBytes
Sat Feb 02, 2013 8:00 am
Forum: General Bullet Physics Support and Feedback
Topic: Softbody motion issues
Replies: 20
Views: 18770

Re: Matching softbodies to 3D objects - no motionstate?

OK well I've made some progress and have what visually looks like a working simulation, although my 3D object is not being translated yet. However, I have some weirdness that I'm not sure where to start looking. I'm dropping a basic 8 sides cylinder onto a rigid body box which is resting on a rigid ...
by SynapticBytes
Sat Feb 02, 2013 1:02 am
Forum: General Bullet Physics Support and Feedback
Topic: What is the advantage of ghost collision detection?
Replies: 4
Views: 5112

Re: What is the advantage of ghost collision detection?

Yeah probably should. The pain with bullet google if you don't include the the site filter is the 100's of duplicate references to the api's for everybody that's reimplemented the library :)
by SynapticBytes
Sat Feb 02, 2013 12:33 am
Forum: General Bullet Physics Support and Feedback
Topic: What is the advantage of ghost collision detection?
Replies: 4
Views: 5112

Re: What is the advantage of ghost collision detection?

Thanks again, It's nice to see someone responding to posts on the forum :) I guess my original question was comparing the scenario where I was just allowing the user to say "check all ghost objects for me" without have the ghosts managed separately. I'll check out the threads you linked. I...