Search found 96 matches

by hyyou
Tue Sep 06, 2016 2:21 am
Forum: General Bullet Physics Support and Feedback
Topic: my linked rigid bodies limp, how can I get joints locked
Replies: 11
Views: 9876

Re: my linked rigid bodies limp, how can I get joints locked

@drleviathan, thank for the useful link to your thread. There is no way to achieve this using 6Dof's or even btFixedConstraint. Is btFixedConstraint somehow stable than 6Dof? Why? I always thought they were the same. beyond about 5 or 6 Fixed constraints in a single chain it gets noticeably soft. I ...
by hyyou
Wed Aug 31, 2016 2:30 am
Forum: General Bullet Physics Support and Feedback
Topic: Efficiently add/remove objects to/from the dynamics world
Replies: 7
Views: 7696

Re: Efficiently add/remove objects to/from the dynamics worl

The official somewhere stated that - try to use primitive if possible ; it is cheaper than triangle mesh. I don't know if it is still applicable for this case. I am using a triangle mesh rigid body instead of a compound body. You use mesh, so you have to modify mesh's shape if terrain is modified, r...
by hyyou
Tue Aug 30, 2016 2:45 pm
Forum: General Bullet Physics Support and Feedback
Topic: Efficiently add/remove objects to/from the dynamics world
Replies: 7
Views: 7696

Re: Efficiently add/remove objects to/from the dynamics worl

Sorry, I encapsulated Bullet and execute most of Bullet's operation via it.
Thus, it is not trivial to create a test case.

Remove/Re-add is very expensive but not as much as I thought, though.
by hyyou
Tue Aug 30, 2016 2:40 pm
Forum: General Bullet Physics Support and Feedback
Topic: compound shape help
Replies: 4
Views: 4918

Re: compound shape help

benelot, for me it is Rigid (simple shape) vs Compound.

I tried to do a merge C1+C2->B, but I forget to disable C1 & C2.
by hyyou
Fri Aug 26, 2016 5:07 am
Forum: General Bullet Physics Support and Feedback
Topic: compound shape help
Replies: 4
Views: 4918

Re: compound shape help

I had this problem once. It was exactly about compound-shape & move-by-itself. To debug, make sure you have only 1 body (the compound) in the world & no gravity. Let's see if it still dare to move by itself. In my case, the velocity came from an invisible collision response, and it was bug i...
by hyyou
Mon Aug 22, 2016 2:08 am
Forum: General Bullet Physics Support and Feedback
Topic: Jittering and shaking when moving a rigidBody
Replies: 20
Views: 29060

Re: Jittering and shaking when moving a rigidBody

I am only a beginner, but as far as I know, kinematic is not designed to receive force from automated collision response. I doubt, setting velocity in every frame shouldn't cause jitter, otherwise Bullet would have rather-severe fault/bug. Where did you call set velocity? - hopefully not inside some...
by hyyou
Fri Aug 19, 2016 2:02 am
Forum: General Bullet Physics Support and Feedback
Topic: custom collision response to control the impulse, possible?
Replies: 0
Views: 3446

custom collision response to control the impulse, possible?

Does Bullet have any callback that let me override calculation of impulse of some pair of colliding btRigidBody manually? e.g. B C and D are btRigidBody. If I set my special UserData to B & C, when B & C collide each other, it will call my custom collision response similar to this :- collisi...
by hyyou
Fri Aug 19, 2016 1:48 am
Forum: General Bullet Physics Support and Feedback
Topic: Jittering and shaking when moving a rigidBody
Replies: 20
Views: 29060

Re: Jittering and shaking when moving a rigidBody

I have never set velocity directly every frame.
I always change velocity by apply impulse, and never encounter any jittering.

If you are hurry, a simple code to reproduce the issue can induce faster and better response from people.
by hyyou
Thu Aug 18, 2016 2:30 pm
Forum: General Bullet Physics Support and Feedback
Topic: How to create custom constraints?
Replies: 2
Views: 3856

How to create custom constraints?

I want to create a new constraint type that work a little different from btGeneric6DofSpring2Constraint. The difference is that user can set (i.e. customize) "mass", "center of mass" and "inertia" (if involved) of body A and B in constraint perspective . For example , T...
by hyyou
Thu Aug 18, 2016 2:01 am
Forum: General Bullet Physics Support and Feedback
Topic: Updating COM every frame?
Replies: 4
Views: 5007

Re: Updating COM every frame?

@benelot Constraint is easy, but it is too unstable and expensive. While 1 Compound with 400 simple shapes is reasonably fast (thank developer!), "400 Simple Body + 399 Constraint" is unusably slow and cause explosion from divergence - even with good mass. I tested it with btGeneric6DofSpr...
by hyyou
Wed Aug 17, 2016 1:39 am
Forum: General Bullet Physics Support and Feedback
Topic: Updating COM every frame?
Replies: 4
Views: 5007

Re: Updating COM every frame?

I have the exact same problem. Thank you for posting. The solution may appear in Scorpion81's fracture source code in http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=12&t=10883 . I just skimmed it. If you would make some progress, I will greatly appreciate if you share the knowledge. ...
by hyyou
Tue Aug 16, 2016 4:08 am
Forum: Physics authoring tools, serialization, standards and related topics
Topic: Blender Fracture Modifier - Compound Fracture Support
Replies: 1
Views: 36866

Re: Blender Fracture Modifier - Compound Fracture Support

Hello, scorpion81 I have played the plugin. It is great and thank for your help in the forum! Now, I am interested in your code and still digging it. Besides the code itself, do you have some document / more description about your modification of Bullet? It will really help my digging process. If yo...
by hyyou
Mon Aug 15, 2016 12:26 pm
Forum: General Bullet Physics Support and Feedback
Topic: Forum moderators/custodians/janitors?
Replies: 6
Views: 16525

Re: Forum moderators/custodians/janitors?

I second the idea that there should be someone to remove those spams / edit some posts. For example, many KennethTColman's advertisement in April 2016 are not removed, and now it is August 2016 already. More spams will cause newcomers think that this library was abandoned, then they will flee away. ...
by hyyou
Mon Aug 15, 2016 8:38 am
Forum: General Bullet Physics Support and Feedback
Topic: Efficiently add/remove objects to/from the dynamics world
Replies: 7
Views: 7696

Re: Efficiently add/remove objects to/from the dynamics worl

I am also facing that same problem as OP, at the exact same lines of code. In my case, "chunk" is a compound body - compose of many child shapes. If I want to add/remove a single child shape from the compound body, or change collision mask, I will have to remove and add the whole body back...
by hyyou
Fri Jul 15, 2016 11:02 am
Forum: General Bullet Physics Support and Feedback
Topic: Is Bullet still in use? Recommended for 2016 new title?
Replies: 4
Views: 10096

Re: Is Bullet still in use? Recommended for 2016 new title?

I started to create a C++ game, at the beginning of this year (2016). I have decided to use Bullet Physics. Now, I still don't think it is a bad decision, and my code is around 10000+ lines now. I have little experience in UE, but one of my friends (project manager) tell me that:- I wish my project ...