Search found 47 matches

by steven
Tue May 21, 2019 11:27 am
Forum: General Bullet Physics Support and Feedback
Topic: SoftBody: modeling a rope from trimesh
Replies: 6
Views: 195

Re: SoftBody: modeling a rope from trimesh

i find that there are duplicated vertex in the array of gVerticesRope, the engine will create a node for each vertex when this array is passed to the btSoftBody(), so there will be more than one node for a same point that is not what we expect. i think you need to re-design your gVerticesRope/gIndic...
by steven
Mon May 20, 2019 1:53 am
Forum: General Bullet Physics Support and Feedback
Topic: SoftBody: modeling a rope from trimesh
Replies: 6
Views: 195

Re: SoftBody: modeling a rope from trimesh

Could you first change your mesh? i would like to work with you to find the root cause.
i also noted that the first and last note are not located at the end of this rope.
by steven
Sun May 19, 2019 10:42 am
Forum: PyBullet Support and Feedback
Topic: Joint friction
Replies: 5
Views: 152

Re: Joint friction

you can google the damping then you can know what the damping is used for. the damping force is a resistence that proportional to the velocity but in the opposite direction. as for the implementation in this engine, honestly so far i still don't understand what that equation below comes from. for mo...
by steven
Fri May 17, 2019 9:12 am
Forum: PyBullet Support and Feedback
Topic: Joint friction
Replies: 5
Views: 152

Re: Joint friction

1. p.setJointMotorControl2(obj,1,p.VELOCITY_CONTROL,targetVelocity=0,force=frictionForce)
2. p.changeDynamics(obj,j,linearDamping=value1, angularDamping=value2)

for my understanding, these two get the similar result with different methods. you can try it and see if get what you want.
by steven
Fri May 17, 2019 1:45 am
Forum: PyBullet Support and Feedback
Topic: Joint friction
Replies: 5
Views: 152

Re: Joint friction

self._p.setJointMotorControlArray(self.kuka_uid, self._motor_indices, self._p.VELOCITY_CONTROL, forces=np.zeros(len(self._motor_indices))) i think this is a method to simulate the joint friction, like the angularDamping. self._p.changeDynamics(self.kuka_uid, self._motor_indices, lateralFriction=fri...
by steven
Thu May 16, 2019 12:20 pm
Forum: General Bullet Physics Support and Feedback
Topic: SoftBody: modeling a rope from trimesh
Replies: 6
Views: 195

Re: SoftBody: modeling a rope from trimesh

after removing the "psb->m_cfg.kMT = 0.5;" it will become the one like below which seems that your mesh is constructed of some separate parts.
Collide1.png
Collide1.png (60.61 KiB) Viewed 179 times
by steven
Thu May 16, 2019 8:24 am
Forum: General Bullet Physics Support and Feedback
Topic: RayTest randomly failing
Replies: 5
Views: 154

Re: RayTest randomly failing

i also run it with very high fps with different parameters, but my hit point always is (-5.046927:1.000000:39.472855).

Code: Select all

while(1)
        castRays();
i compile it with double precision enabled, maybe this is the main difference between us.

good luck!
by steven
Thu May 16, 2019 7:37 am
Forum: General Bullet Physics Support and Feedback
Topic: RayTest randomly failing
Replies: 5
Views: 154

Re: RayTest randomly failing

i just do a test with your data, all the result is as expected. from(-5.087273,0.000000,39.472855) to(-5.025157,0.000000,39.472855) hasHit ..........-5.046927:1.000000:39.472855 from(-5.099017,0.000000,39.472855) to(-5.037612,0.000000,39.472855) hasHit ..........-5.046927:1.000000:39.472855 from(-5....
by steven
Thu May 16, 2019 1:52 am
Forum: General Bullet Physics Support and Feedback
Topic: RayTest randomly failing
Replies: 5
Views: 154

Re: RayTest randomly failing

Could you provide the positions of your rigidbody? i want to reproduce this issue and find the root cause with you. thanks.
by steven
Tue May 14, 2019 1:14 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unexplained behaviour with rigidbody applyImpulse
Replies: 15
Views: 276

Re: Unexplained behaviour with rigidbody applyImpulse

Could you provide some simple example? thanks.
by steven
Mon May 13, 2019 8:15 am
Forum: General Bullet Physics Support and Feedback
Topic: Incorrect collision results with concave shapes (contact manifolds, but 0 contact points)
Replies: 11
Views: 211

Re: Incorrect collision results with concave shapes (contact manifolds, but 0 contact points)

after changing to tag 2.82(git checkout 2.82), i find the GimpactTestDemo. i don't know why it is deleted in the later version. hope it is useful for future user.
by steven
Sun May 12, 2019 9:33 am
Forum: General Bullet Physics Support and Feedback
Topic: Incorrect collision results with concave shapes (contact manifolds, but 0 contact points)
Replies: 11
Views: 211

Re: Incorrect collision results with concave shapes (contact manifolds, but 0 contact points)

add a picture to clarify this case. any ideas about the gimpact mesh is helpful, thanks in advance.
collisionConaves.png
collisionConaves.png (29.69 KiB) Viewed 104 times
by steven
Sun May 12, 2019 5:23 am
Forum: General Bullet Physics Support and Feedback
Topic: Incorrect collision results with concave shapes (contact manifolds, but 0 contact points)
Replies: 11
Views: 211

Re: Incorrect collision results with concave shapes (contact manifolds, but 0 contact points)

I have also tried using btGImpactMeshShape, with no change in results. Could you post some code of how did you use the btGImpactMeshShape? i will try it later. i find the algorithm for the gimpact need to be regiestered externally like below. btCollisionDispatcher * dispatcher = static_cast<btColli...
by steven
Sun May 12, 2019 4:17 am
Forum: General Bullet Physics Support and Feedback
Topic: Incorrect collision results with concave shapes (contact manifolds, but 0 contact points)
Replies: 11
Views: 211

Re: Incorrect collision results with concave shapes (contact manifolds, but 0 contact points)

your two collison objects all are the concave but now the engine doesn't support the concave vs. convave collision in the narrowphase. you can refer to this function btDefaultCollisionConfiguration::getCollisionAlgorithmCreateFunc() in file btdefaultcollisionconfiguration.cpp for details. i think yo...
by steven
Sat May 11, 2019 9:08 am
Forum: General Bullet Physics Support and Feedback
Topic: Incorrect collision results with concave shapes (contact manifolds, but 0 contact points)
Replies: 11
Views: 211

Re: Incorrect collision results with concave shapes (contact manifolds, but 0 contact points)

i just write a similar test but use two boxes instead of the concave and don't find the issue you said. so next i need the data to create the concave shape. thanks. I know from other posts on this forum that a contact manifold is created in the broadphase based on AABB intersection and may reasonabl...