Search found 34 matches

by avithohol
Tue Nov 06, 2018 11:06 pm
Forum: General Bullet Physics Support and Feedback
Topic: How to make crouching. Change collision shape on the fly?
Replies: 6
Views: 2796

Re: How to make crouching. Change collision shape on the fly?

I know its old but in case somebody come across.

This works for me:

rigidBody->getCollisionShape()->setLocalScaling(btVector3(1,0.5,1));

This scale my body's capsule shape half sized on the Y axis.
by avithohol
Mon May 28, 2018 8:43 pm
Forum: General Bullet Physics Support and Feedback
Topic: Minimalist game loop with tunneling
Replies: 12
Views: 2707

Re: Minimalist game loop with tunneling

Hi drleviathan, thanks for the feedback, I actually did read that thread before making my post, but I didn't see an answer that actually fixed the OP's problem. And since I'm having the same problem, I wanted to add to the discussion in case 2.87 has a bug it's just simple dropping of objects under...
by avithohol
Sun Apr 29, 2018 1:09 pm
Forum: General Bullet Physics Support and Feedback
Topic: Minimalist game loop with tunneling
Replies: 12
Views: 2707

Re: Minimalist game loop with tunneling

I am out of idea. I have never faced such problem for the built-in btBoxShape. Perhaps, it is limitation of btBvhTriangleMeshShape or its margin. (more info about margin) https://www.youtube.com/watch?v=BGAwRKPlpCw Thanks, I knew that video, and tried many margin combination. My findings are here: ...
by avithohol
Sun Apr 29, 2018 1:07 pm
Forum: General Bullet Physics Support and Feedback
Topic: Minimalist game loop with tunneling
Replies: 12
Views: 2707

Re: Minimalist game loop with tunneling

Thanks for the reply. Yep, I do use substeps, and MotionStates, giving the best results, that's what the attached code shows. Currently my best "workaround" is to "increase" the resolution to 1/120. From my own perspective: there isn't much new info to add: Box is 1x1x1m and falls from 7m with downw...
by avithohol
Thu Apr 26, 2018 9:32 pm
Forum: General Bullet Physics Support and Feedback
Topic: Minimalist game loop with tunneling
Replies: 12
Views: 2707

Re: Minimalist game loop with tunneling

No replies could mean, there is nothing else can be done beside what is already outlined in the question.

Or no replies can mean i asked the question wrong :)
by avithohol
Sun Apr 08, 2018 11:02 pm
Forum: General Bullet Physics Support and Feedback
Topic: btBvhTriangleMeshShape tunneling
Replies: 9
Views: 1928

Re: btBvhTriangleMeshShape tunneling

I have post it to a new, and more question with a full example, you can follow:
https://pybullet.org/Bullet/phpBB3/view ... =9&t=12051

This thread won't have anymore answers specifically on btBvhTriangleMeshShape vs btBoxShape, which is there, but not that significant.
by avithohol
Sun Apr 08, 2018 10:59 pm
Forum: General Bullet Physics Support and Feedback
Topic: Minimalist game loop with tunneling
Replies: 12
Views: 2707

Minimalist game loop with tunneling

I have created a minimalist game loop example using GL3 + GLEW + SDL2 + GLM + BulletPhysics 2.87. See attached executable, and VisualStudio 2017 solution. Just extract it to C drive, and run. Video, for those who don't want to download the sample: https://youtu.be/PIuBNMW-tbo Could anybody help me u...
by avithohol
Sat Apr 07, 2018 9:30 pm
Forum: General Bullet Physics Support and Feedback
Topic: btBvhTriangleMeshShape tunneling
Replies: 9
Views: 1928

Re: btBvhTriangleMeshShape tunneling

Suppose you had a 10m cubic box and your substep period was 1/60 sec. What is the lowest speed at which tunneling through a thin triangle would be possible? If the box were to hit the triangle face-on and manage to tunnel 50%+ through, then Bullet's penetration resolution algorithm will conclude th...
by avithohol
Sat Apr 07, 2018 9:23 pm
Forum: General Bullet Physics Support and Feedback
Topic: btBvhTriangleMeshShape tunneling
Replies: 9
Views: 1928

Re: btBvhTriangleMeshShape tunneling

I believe it is very fast, but not sure if it is too fast. I just noticed that, at some time-steps, it looks like stack of box simulation. Try to enable "SOLVER_RANDMIZE_ORDER". (http://bulletphysics.org/mediawiki-1.5.8/index.php/BtContactSolverInfo) I am curious if it helps. Interesting. Never use...
by avithohol
Thu Apr 05, 2018 11:04 am
Forum: General Bullet Physics Support and Feedback
Topic: btBvhTriangleMeshShape tunneling
Replies: 9
Views: 1928

Re: btBvhTriangleMeshShape tunneling

(I will avoid to repeat what drleviathan already mentioned.) Hmm... I feel that the dropping boxs move quite fast. I am curious. How much are their max speed? There is a rumor that the middle parameter of stepSimulation() should be 1. (https://stackoverflow.com/a/21273467) I didn't verify it, but I...
by avithohol
Wed Apr 04, 2018 10:59 pm
Forum: General Bullet Physics Support and Feedback
Topic: btBvhTriangleMeshShape tunneling
Replies: 9
Views: 1928

Re: btBvhTriangleMeshShape tunneling

Yes, tunneling is a known fundamental problem for physics simulations and you've already listed the known solutions. In summary: (1) Only use convex shapes. Use convex decomposition and btCompoundShape for concave things. (2) Use smaller substeps (3) Enable continuous collision detection (CCD) Than...
by avithohol
Tue Apr 03, 2018 9:53 pm
Forum: General Bullet Physics Support and Feedback
Topic: btBvhTriangleMeshShape tunneling
Replies: 9
Views: 1928

btBvhTriangleMeshShape tunneling

There seems to be significant differences between collision shapes regarding collision accuracy. The same dynamic bodies penetrate much deeper into a static btBvhTriangleMeshShape body, than they do into the same sized static btBoxShape body. For test, one big 10x10x10 box is created, then 9 dynamic...
by avithohol
Sun Feb 25, 2018 9:16 pm
Forum: General Bullet Physics Support and Feedback
Topic: Back to the future hoverboard
Replies: 4
Views: 1172

Re: Back to the future hoverboard

StabInTheDark wrote:
Sun Feb 25, 2018 7:01 pm
Just use the raycast vehicle controller with out the wheels.
Didn't think about that, worth a try. Thanks!
by avithohol
Sun Feb 25, 2018 3:04 pm
Forum: General Bullet Physics Support and Feedback
Topic: Back to the future hoverboard
Replies: 4
Views: 1172

Re: Back to the future hoverboard

Here's an idea. Use a "spring action" to modify the hoverboard's velocity. Here is an implementation that might work. Some of the parameters need to be tuned to suit your needs. Thanks very much! I get your idea. Though it's blowing the body away madly at the moment (I have different scales), I und...
by avithohol
Sat Feb 24, 2018 4:09 pm
Forum: General Bullet Physics Support and Feedback
Topic: Back to the future hoverboard
Replies: 4
Views: 1172

Back to the future hoverboard

Hello, I am trying to implement hoverboard effect with the API, but my attempts failed so far: https://youtu.be/88sTBjYXHxg Hoverboard: Same as in the movie . Basically one rigidbody hover over various ground surface, about 50cm. What i tried so far is to constantly apply force (or impulse) in pre-t...