Search found 849 matches
- Wed May 20, 2015 4:03 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Disappointed with Bullet physics simulation speed...
- Replies: 9
- Views: 7958
Re: Disappointed with Bullet physics simulation speed...
I'm wondering: are you sharing the box shape? When multiple boxes have the same dimensions you can make one btBoxShape instance and give that to each RigidBody that needs it -- this should help things run a little faster (less cache misses), but I don't know by how much since I haven't experimented.
- Mon May 18, 2015 5:03 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Spheres show strange behaviour.
- Replies: 6
- Views: 4514
Re: Spheres show strange behaviour.
If you set the sleeping velocity thresholds too low then your objects will never settle! If you want that behavior just for those objects (and not the rest of the world) you can call btRigidBody::setActivationState(DISABLE_DEACTIVATION) instead.
- Mon May 18, 2015 4:00 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Spheres show strange behaviour.
- Replies: 6
- Views: 4514
Re: Spheres show strange behaviour.
In Bullet 2.8.2 the default values for linear and angular sleeping velocities are: 0.8 m/sec and 1.0 radians/sec respectively. These are hard-coded magic numbers in the btRigidBody constructor implementation. You'll have to experiment with different values to find something that works for you, altho...
- Mon May 18, 2015 12:59 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Spheres show strange behaviour.
- Replies: 6
- Views: 4514
Re: Spheres show strange behaviour.
Bullet will deactivate moving objects that are going slow enough for a long enough period of time. When the spheres reach the top of their arc they are moving slowly so they are candidates for deactivation. You can change the threshold velocities (linear and angular) at which objects are considered ...
- Wed May 13, 2015 4:44 am
- Forum: General Bullet Physics Support and Feedback
- Topic: Does anyone now how to use btCompoundShape???!!! ( HELP )
- Replies: 4
- Views: 3135
Re: Does anyone now how to use btCompoundShape???!!! ( HELP
So... what's the error?
Is it a compile error? a link error? or a runtime error?
Is it a compile error? a link error? or a runtime error?
- Tue May 12, 2015 12:17 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Collision filter mask works ugly
- Replies: 4
- Views: 7224
Re: Collision filter mask works ugly
He means that if you write 10 in 16-bit binary you get: 0000 0000 0000 1010. What matters is that two bits are set: the second bit from right, which represents the value 2, and the fourth bit from right, which represents the value 8 -- add them together and you get 10. Similarly 25 would look like: ...
- Mon May 11, 2015 2:38 am
- Forum: General Bullet Physics Support and Feedback
- Topic: Change position of a convex hull after creation
- Replies: 5
- Views: 5054
Re: Change position of a convex hull after creation
Do you want to change the transform of the body that uses the shape? If so, then you can just use btCollisionBody::setWorldTransform(). Or do you need to change the local transform of the btConvexHullShape itself? If this is the case then there are two ways to do it: (1) Create an entirely new shape...
- Sun May 10, 2015 5:02 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: How to get btShape volume?
- Replies: 3
- Views: 4023
Re: How to get btShape volume?
I have some code that can compute the volume, center of mass, and inertia tensor of closed meshes and I've been looking for an excuse to clean it up and submit for public use. I'll try to get around to it, but I don't think I can get to it today.
- Thu May 07, 2015 3:18 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: [Solved] raycasting bullet vehicle
- Replies: 8
- Views: 9239
Re: Does anyone now how to use btConvexHullShape???!!! ( HEL
Yes sorry, that was a typo. Use dynamicsEngine->addRigidBody(body);
- Wed May 06, 2015 11:21 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: [Solved] raycasting bullet vehicle
- Replies: 8
- Views: 9239
Re: Does anyone now how to use btConvexHullShape???!!! ( HEL
To create a btConvexHull shape you would do something like this: int NUM_POINTS = 5; btVector3 points[NUM_POINTS] = { btVector3(-0.5, 1, 1), btVector3(-0.5, 1, -1), btVector3(-0.5,-1, 1), btVector3(-0.5,-1, -1), btVector3( 1, 0, 0) }; btConvexHullShape* shape = new btConvexHullShape(); for (int i = ...
- Mon May 04, 2015 5:26 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Contact forces in Bullet
- Replies: 7
- Views: 8832
Re: Contact forces in Bullet
I don't think Bullet would be a good choice for analyzing forces between touching objects. You'll probably need to use a different physics engine (probably a soft-body simulation). Does your simulation need to be real-time or can your simulation at offline speeds? A real-time game physics engine oft...
- Sun Apr 26, 2015 3:03 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: A bullet in Bullet, ray test missing hits
- Replies: 2
- Views: 3585
Re: A bullet in Bullet, ray test missing hits
It sounds like you want to use Continuous Collision Detection (CCD). You should look at the ContinuousConvexCollision Demo or maybe read this wiki page/FAQ.
- Sun Apr 26, 2015 2:48 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Collision counter in bullet physics
- Replies: 1
- Views: 2817
Re: Collision counter in bullet physics
Bullet doesn't provide a system to generate collision events between objects -- you have to write your own. If you search these forums or other pages you might find examples that people have provided. Here is a modified system that I pulled out of a project I'm working on, which itself was based on ...
- Fri Apr 24, 2015 2:49 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: How can I rotate an object's velocity?
- Replies: 3
- Views: 3889
Re: How can I rotate an object's velocity?
I believe it is safe to change the velocity of an object directly, despite its collisions. Within reason, of course -- setting the velocity very high or pushing the object deeper into penetration can only cause problems.
- Fri Apr 24, 2015 4:18 am
- Forum: General Bullet Physics Support and Feedback
- Topic: Getting surface normal from manifold
- Replies: 1
- Views: 2610
Re: Getting surface normal from manifold
My experience has been that btManifoldPoint::m_normalWorldOnB is pretty accurate as to the surface normal of the contact so I would expect it to be usable for most applications. Meanwhile the btSingleRayCallback method should also work in theory. You would test a ray against the other collision obje...