Search found 191 matches

by Dragonlord
Thu Jul 27, 2017 8:21 pm
Forum: General Bullet Physics Support and Feedback
Topic: Generic6DOF joint friction bugged (with example)
Replies: 5
Views: 1833

Re: Generic6DOF joint friction bugged (with example)

I've setup another example with the kinematic joint friction case. Bullet is definitely bugged since it is unable to counter gravity using a motor even if the force is set ridiculously high. The atteched example shows the problem. If nobody is going to take a look at this problem I'm going to throw ...
by Dragonlord
Mon Jul 24, 2017 2:34 pm
Forum: General Bullet Physics Support and Feedback
Topic: Generic6DOF joint friction bugged (with example)
Replies: 5
Views: 1833

Re: Generic6DOF constraint cancel force problem

I tried putting together a test case in ExampleBrowser (getting this to work is a real pain). The attached file is the first part of the problem, the one with the constraint doing strange things right at the start. In my real test case this also leads to strange jittering but I could not directly re...
by Dragonlord
Thu Jul 20, 2017 10:49 pm
Forum: General Bullet Physics Support and Feedback
Topic: Generic6DOF joint friction bugged (with example)
Replies: 5
Views: 1833

Re: Generic6DOF constraint cancel force problem

I did some more testings and after running into a strange problem where the first step produces a linear velocity that should not be there I have the suspicion Bullet is bugged. Can somebody confirm this behavior to be wrong? // before doing simulation step (showing state after last simulation step)...
by Dragonlord
Tue Jul 18, 2017 5:16 pm
Forum: General Bullet Physics Support and Feedback
Topic: Generic6DOF joint friction bugged (with example)
Replies: 5
Views: 1833

Re: Generic6DOF constraint cancel force problem

That's not the final goal. This is just a step in between to get it working. What I want in the end is inner joint friction, hence the joint resisting to be moved along the limited degree of freedom, like a rusty hinge on a door.
by Dragonlord
Sun Jul 16, 2017 10:37 pm
Forum: General Bullet Physics Support and Feedback
Topic: Generic6DOF joint friction bugged (with example)
Replies: 5
Views: 1833

Generic6DOF joint friction bugged (with example)

I try to setup a linear motor on a generic 6dof constraint subclass with the simple task of cancelling all forces to keep a platform (no angular movement, only linear up-down movement possible) at a steady altitude. It's a preparation for more but I can't even get this simple problem working. I do t...
by Dragonlord
Tue Dec 02, 2014 5:31 pm
Forum: General Bullet Physics Support and Feedback
Topic: btDbvtBroadphase very slow on sweep/ray testing
Replies: 6
Views: 3189

Re: btDbvtBroadphase very slow on sweep/ray testing

The optimization on the height terrain testing itself I can't share since it ties directly into my engine code and objects. The missing call-in point though can be patched with the patch file. It affects ray casts and convex casts but not the calls inside btCollisionWorld physics simulation due to t...
by Dragonlord
Mon Dec 01, 2014 6:01 pm
Forum: General Bullet Physics Support and Feedback
Topic: btDbvtBroadphase very slow on sweep/ray testing
Replies: 6
Views: 3189

Re: btDbvtBroadphase very slow on sweep/ray testing

It sounds like a serious bug. There is an issue tracker here: https://github.com/bulletphysics/bullet3/issues If I'm not mistaken this bug tracker is for bullet v3 but this problem affects bullet v2. That said I've tracked down the problem to btHeightTerrain. It's testing every single triangle in t...
by Dragonlord
Fri Nov 28, 2014 11:20 pm
Forum: General Bullet Physics Support and Feedback
Topic: btDbvtBroadphase very slow on sweep/ray testing
Replies: 6
Views: 3189

btDbvtBroadphase very slow on sweep/ray testing

The implementation of btDbvtBroadphase seems to have a serious performance issue. To see the problem create a simple work with btDbvtBroadphase. Add a few objects in it. Now try to make a convexSweepTest with a small sphere (for example 0.01 radius for example) or a rayHits test with a distance vect...
by Dragonlord
Sun Nov 23, 2014 12:28 pm
Forum: General Bullet Physics Support and Feedback
Topic: Joint constraint friction
Replies: 11
Views: 4569

Re: Joint constraint friction

What I find in the source is this: btScalar mot_fact = getMotorFactor( limot->m_currentPosition, limot->m_loLimit, limot->m_hiLimit, tag_vel, info->fps * limot->m_stopERP); info->m_constraintError[srow] += mot_fact * limot->m_targetVelocity; info->m_lowerLimit[srow] = -limot->m_maxMotorForce; info-...
by Dragonlord
Sat Nov 22, 2014 3:52 pm
Forum: General Bullet Physics Support and Feedback
Topic: Joint constraint friction
Replies: 11
Views: 4569

Re: Joint constraint friction

What I find in the source is this: btScalar mot_fact = getMotorFactor( limot->m_currentPosition, limot->m_loLimit, limot->m_hiLimit, tag_vel, info->fps * limot->m_stopERP); info->m_constraintError[srow] += mot_fact * limot->m_targetVelocity; info->m_lowerLimit[srow] = -limot->m_maxMotorForce; info->...
by Dragonlord
Sat Nov 22, 2014 10:56 am
Forum: General Bullet Physics Support and Feedback
Topic: Joint constraint friction
Replies: 11
Views: 4569

Re: Joint constraint friction

What exactly is the meaning of the max torque? Is it like target velocity? Constraints are basically optimization problems where you seek the minimum force needed to keep a desired velocity. If you can hit 0 velocity with less than your maximum friction force, it'll use less force than the max, but...
by Dragonlord
Fri Nov 21, 2014 4:37 pm
Forum: General Bullet Physics Support and Feedback
Topic: Joint constraint friction
Replies: 11
Views: 4569

Re: Joint constraint friction

In this case just inner friction of a joint. I've looked at the topic but it uses motors and only 6dof has motors as far as I get it. btHingeConstraint and Hinge2Constraint also have them, just use enableAngularMotor with 0 target velocity and max torque being equal to max friction What exactly is ...
by Dragonlord
Thu Nov 20, 2014 9:06 pm
Forum: General Bullet Physics Support and Feedback
Topic: Y-Axis bug in 6Dof
Replies: 0
Views: 2087

Y-Axis bug in 6Dof

I would like to see if somebody else has this bug in 2.82 . I take a simple door object, a box of something like size=(0.1, 2, 1.2) at (0,1,0) with a 6Dof constraint attached to the fixed body at (0,0,0) with 0 gravity. Now the following happens (angles always converted to radians). 1) x-axis range ...
by Dragonlord
Thu Nov 20, 2014 5:48 pm
Forum: General Bullet Physics Support and Feedback
Topic: Joint constraint friction
Replies: 11
Views: 4569

Re: Joint constraint friction

In this case just inner friction of a joint. I've looked at the topic but it uses motors and only 6dof has motors as far as I get it.
by Dragonlord
Wed Nov 19, 2014 11:28 pm
Forum: General Bullet Physics Support and Feedback
Topic: Joint constraint friction
Replies: 11
Views: 4569

Joint constraint friction

I'm trying to implement the simple concept of friction in constraints, for example a rusty door. The existing bullet constraints seem to be friction-less and do not seem to expose anything related to this. Now I'm trying to figure out how friction in joint constraints would have to be added ontop of...