Search found 849 matches
- Mon Jul 25, 2022 3:36 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: VR compilation error
- Replies: 2
- Views: 4080
Re: VR compilation error
AFAICT it does indeed expect four arguments: B3_SHARED_API int b3PhysicsParamSetGravity(b3SharedMemoryCommandHandle commandHandle, double gravx, double gravy, double gravz); Check its declaration in the header to make sure: examples/SharedMemory/PhysicsClientC_API.h What version of the repository is...
- Thu Jul 21, 2022 3:11 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Rendering Issues when importing urdf linked to .obj
- Replies: 1
- Views: 4139
Re: Rendering Issues when importing urdf linked to .obj
You might want to try asking in the python-specific forum. This is the support thread for underlying C++ library.
- Thu Jul 21, 2022 3:10 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Rendering Only Specific Objects in Camera
- Replies: 1
- Views: 3265
Re: Rendering Only Specific Objects in Camera
You might want to try asking in the python-specific forum. This is the support thread for underlying C++ library.
- Wed Jun 29, 2022 2:54 am
- Forum: General Bullet Physics Support and Feedback
- Topic: Skeletal Animation
- Replies: 1
- Views: 3734
Re: Skeletal Animation
Here are some scenarios of increasing complexity: (1) Kinematic character always collides like a capsule (or some other simple shape) regardless of their animation state. (2) Dynamic character always collides like a capsule (or some other simple shape) regardless of their animation state. (3) Charac...
- Mon May 30, 2022 3:38 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: wrong collide result
- Replies: 3
- Views: 5212
Re: wrong collide result
You're probably experiencing the collision margin of some convex-convex shape collisions. There is an old video on YouTube that illustrates margin.
- Tue May 10, 2022 4:30 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Max number of elements?
- Replies: 1
- Views: 8779
Re: Max number of elements?
There is not enough information to answer your question. You will just have to try it to find out. Here are some questions about things that would affect the answer: Are all the elements dynamic? Or are some of them static or kinematic? Are all of the elements rigid bodies? Or will you be needing so...
- Thu May 05, 2022 3:13 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: How to know if a body is colliding
- Replies: 1
- Views: 4516
Re: How to know if a body is colliding
One way to do it is to scan all of the contact manifolds after each step. So something like this: void updateContactMap(btCollisionDispatcher* collision_dispatcher) { int num_manifolds = collision_dispatcher->getNumManifolds(); for (int i = 0; i < num_manifolds; ++i) { btPersistentManifold* contact_...
- Thu May 05, 2022 2:59 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Jitter when a btBoxShape moves against a btConvexHullShape.
- Replies: 2
- Views: 4510
Re: Jitter when a btBoxShape moves against a btConvexHullShape.
Make the conveyor kinematic instead of static, give it a non-zero velocity but don't change its position. Then dynamic objects that touch it will pick up the non-zero velocity from the collision and will move along.
- Thu Apr 28, 2022 3:28 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Static `btConvexHullShape` Not Participating in Collisions
- Replies: 2
- Views: 4083
Re: Static `btConvexHullShape` Not Participating in Collisions
btConvexHullShape does work, so I would expect something else is wrong. Does the object properly collide when you supply it with a different shape but leave all other code unchanged?
- Sat Apr 23, 2022 4:41 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: How to remove vehicle/rigidbody from dynamics worlds without deleting memory
- Replies: 3
- Views: 5012
Re: How to remove vehicle/rigidbody from dynamics worlds without deleting memory
Yes, if you remove a body from the dynamics world then it will not collide. There are ways to leave a body in the dynamics world while disabling all or selective collisions. One way to do this is to assign each object to one or more collision groups and to specify which groups it collides with. This...
- Tue Apr 19, 2022 3:44 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: How to create a homing missile?
- Replies: 7
- Views: 14888
Re: How to create a homing missile?
I forgot to mention some other ideas: (5) As hinted at in (3) where I mentioned fins + atmospheric substrate... if you provide a stronger coupling between the missile's forward direction and its linear velocity, such that when it changes direction it also tends to re-orient the existing velocity to ...
- Mon Apr 18, 2022 8:17 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: How to create a homing missile?
- Replies: 7
- Views: 14888
Re: How to create a homing missile?
I have a few ideas for making a homing missile smarter: (1) Reduce the value of EXPONENTIAL_TIMESCALE . This will make the missile orient toward its intended target faster. However, this just effectively reduces the orbit radius of the problem you're seeing and it makes the homing behavior more aggr...
- Wed Mar 30, 2022 4:56 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Best way to detect contact points / manifolds of overlapping kinematic bodies?
- Replies: 3
- Views: 5350
Re: Best way to detect contact points / manifolds of overlapping kinematic bodies?
I would guess the 0.2 is a tuned magic number that allows the btKinematicCharacterController to extract itself from penetration over several substeps rather than in one. It moves out 20% every substep and if your simulation is running at 60 substeps per second then the character could reduce penetra...
- Tue Mar 29, 2022 7:07 am
- Forum: General Bullet Physics Support and Feedback
- Topic: How kinematic bodies work under the hood
- Replies: 6
- Views: 9202
Re: How kinematic bodies work under the hood
Sorry, I was getting Lagrangian dynamics confused with the Jacobi method which is what Bullet uses to solve constraints. When solving the Jacobi matrices of the various constraints the iterative method converges on the new final values of the transform and velocities without explicit knowledge of th...
- Mon Mar 28, 2022 10:23 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: How kinematic bodies work under the hood
- Replies: 6
- Views: 9202
Re: How kinematic bodies work under the hood
The pivot on the kinematic object is effectively a constraint of the Lagrangian dynamics. It is determined by the transform/velocities of the kinematic object, which effectively has infinite mass and inertia, and are therefore known as soon as the kinematic object's transform/velocities have been re...