Real-Time Physics Simulation Forum

usamarafiq93 wrote: ↑Wed Jul 03, 2019 3:21 pm Hi,
I have been trying to measure the applied torque through getJointTorque (int dof) and its returning zero.

I guess what you want is btMultiBodyConstraint::getAppliedImpulse(int dof). btMultiBody::getJointTorque(int i) is the external torque applied by the user.

I think using a kinematic object makes more sense. You could animate it in object space and then multiply its transform by the capsule's transform to calculate the final state of the hit box object.

Is the callback invoked at least once or never? Does it happen in single collision and also in resting contact? You have to look at the point where the callback is called by Bullet which is in btPersistentManifold.cpp btPersistentManifold::refreshContactPoints. It only gets called if the contact is ...

I will definitely check it out! Do you know if maybe there is a better way to create robot arm type links rather than using constraints? Constraints are what you gotta use to "constrain" the motion of one object to another. Are you using btMultiBody (Featherstone method)? If not check out...

Where's your contact callback code? Are you using gContactAddedCallback? If so, you have to set a collision flag like this newBody->setCollisionFlags(newBody->getCollisionFlags()|btCollisionObject::CF_CUSTOM_MATERIAL_CALLBACK); You should look into btManifoldResult::addContactPoint to see the logic ...

It seems like the weight had something to do with it alright. The horizontal arm is 100x heavier than the vertical arm and this had definitely made an impact. You should look up the issue there is with large "mass ratios" in Sequential Impulses. The relative mass between interacting objec...

First thing I'd check are the dimensions and mass of your objects. You gotta make sure they're realistic in size and weight and preferably using metric units. If you're using very large or very small numbers or if you have significant discrepancy in size or mass among the interacting objects, you mi...

btBvhTriangleMeshShape cannot be used as a dynamic object. You should use a btCompoundShape for more complex objects, where you simply combine a bunch of convex shapes to get a concave shape.

1. Does this approach make sense? I guess. You should get similar behavior using a capsule shape with a very low center of mass (use a compound shape to displace the center of mass). 2. What's the best way to implement the motor? I see that the 6DOF constraint has motor control members: can I implem...

You could also try disabling islands: mDynamicsWorld->getSimulationIslandManager()->setSplitIslands(false); SOLVER_RANDMIZE_ORDER should be disabled by default so the order of the constraints in the solver shouldn't be randomized, though, they can be indirectly randomized when contact points are not...

In enableAngularMotor you pass the maximum impulse in the last/3rd parameter. Set it to a high number or SIMD_INFINITY.

Please read the manual and look into the examples. "To implement one, simply inherit btMotionState and override getWorldTransform and setWorldTransform." "Bullet calls setWorldTransform with the transform of the body, for you to update your object appropriately." The Ogre3d examp...

I think you're looking for Motion States http://bulletphysics.org/mediawiki-1.5. ... tionStates

You could start your simulation but not render it. Wait for it to stabilize and then present it to the user. It's like, the stabilization task is part of the scene loading task.

Oh well, I mean...I would like to know more about analytical methods to compute collision response forces/impulses for deformable solids, specially finite element solids. I'd like to know about articles which present the state of the art of this. And also if possible, as I said in the previous post,...