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xexuxjy

Member Since 19 Sep 2012
Offline Last Active Today, 09:46 AM

Posts I've Made

In Topic: Creating Box RigidBody From AABB

13 April 2016 - 07:00 AM

Sure. Was trying to remember if bullet allowed you to change the centre of mass  easily and it doesn't though there are ways to work around it using compound shapes but wouldn't recommend it. One solution Erwin mentions below in :

 

http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=2209#p10314

 

is to let your motion state do the graphics offset for you. I'd still probably recommend trying to keep the pivot centred though.


In Topic: Creating Box RigidBody From AABB

13 April 2016 - 05:13 AM

In that case you still need your door mesh to be a centered box, but then have a hinge constaint on it to anchor it to another mesh / rigid body and let the contraint do the work for you. The bullet constraint demo has good examples of this.


In Topic: Creating Box RigidBody From AABB

13 April 2016 - 03:08 AM

Bullet box shape expects a center of mass (center of object) at local zero point to box, so you can imagine that instead of your box going from from 0,0,0->1,1,1 it goes from -0.5,-0.5,-0.5 -> 0.5,0.5,0.5 . I think you'll find using your box much easier in general if you think of it centered that way.

 

You do not need to recalculate the AABB each frame (bullet will do it for you based on the rotation of the object). if you're using the btMotionState to link your model and the rigidbody you should be able to just update your models transform based on that.


In Topic: Anyone using Bullet serialization?

30 September 2015 - 05:48 AM

Looks like the TuxKart team tried something similar (though they seem to have backed it out) :

 

https://github.com/supertuxkart/stk-code/commit/06d9359fa6bcbd4ef53d763194815edcd8e4637e

 

out of interest how big are the meshes that are causing such slow building of the meshshape - are they all around 100 tris and it's just the sheer quantity of them?


In Topic: Anyone using Bullet serialization?

29 September 2015 - 02:10 PM

You've probably seen this :

 

 http://bulletphysics.org/mediawiki-1.5.8/index.php/Bullet_binary_serialization

 

But in general the serialization stuff isn't really that useful apart from helping to debug bullet issues....  You can serialize individual objects, but it's one of these things that snow balls, so a rigid body needs a collision shape, which may then need to serialize the accelerator like the trees for BvhTriangleMesh and so on.

 

I think the 32k issue you've got above may not be a problem though. The serializer works in chunks so that's probably just the default chunk size, you could add a lot more and have it fit inside that same chunk.


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