Real-Time Physics Simulation Forum

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 ...

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...

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)...

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.

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...

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...

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...

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...

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-...

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->...

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...

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 ...

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 ...

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.

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...