Search found 43 matches

by ed_welch
Fri Mar 03, 2023 11:51 am
Forum: General Bullet Physics Support and Feedback
Topic: Kinematic objects colliding with dynamic objects very badly
Replies: 2
Views: 26644

Re: Kinematic objects colliding with dynamic objects very badly

Thanks for the reply. Unfortunately, it makes no difference. I think velocity is ignored for kinematic objects. Edit: I finally figured it out. I was directly updating the WorldTransform, without updating the MotionState. I changed this to update both and now it works great: btTransform& t = m_p...
by ed_welch
Thu Mar 02, 2023 9:10 pm
Forum: General Bullet Physics Support and Feedback
Topic: Kinematic objects colliding with dynamic objects very badly
Replies: 2
Views: 26644

Kinematic objects colliding with dynamic objects very badly

Kinematic objects do not seem to interact very well with dynamic objects. When you call m_pRigidBody->getWorldTransform().setOrigin() it caterpults any dynamic objects in it's way with enormous force. Is this normal?
by ed_welch
Wed Mar 01, 2023 7:53 pm
Forum: General Bullet Physics Support and Feedback
Topic: crash at btConvexHullShape::localGetSupportingVertexWithoutMargin
Replies: 5
Views: 36987

Re: crash at btConvexHullShape::localGetSupportingVertexWithoutMargin

I downloaded the latest version and now it seems to be ok. I no longer get the crash.
by ed_welch
Fri Feb 10, 2023 11:38 am
Forum: General Bullet Physics Support and Feedback
Topic: Some tips and tricks
Replies: 0
Views: 126074

Some tips and tricks

I wrote a blog entry detailing how I solved various problems I had with Bullet physics. I post it here in case it might prove useful to some one https://www.gamedev.net/blogs/entry/227 ... t-physics/
by ed_welch
Wed Feb 08, 2023 9:06 pm
Forum: General Bullet Physics Support and Feedback
Topic: Bizarre behaviour setting position of btRigidBody
Replies: 0
Views: 134839

Bizarre behaviour setting position of btRigidBody

I discovered some bizzarre behaviour of a btRigidBody (with CF_KINEMATIC_OBJECT flag) when you try to set the position of the object. If set activation state to ISLAND_SLEEPING, then the position can be modified with this code: btTransform& t = m_pRigidBody->getWorldTransform(); t.setOrigin(btVe...
by ed_welch
Wed Feb 08, 2023 12:59 am
Forum: General Bullet Physics Support and Feedback
Topic: crash at btConvexHullShape::localGetSupportingVertexWithoutMargin
Replies: 5
Views: 36987

Re: crash at btConvexHullShape::localGetSupportingVertexWithoutMargin

ah, thanks for the answer. I don't use btStaticPlaneShape, so it must be something else in my case.
My solution is to keep using the old version ;)
by ed_welch
Wed Feb 08, 2023 12:54 am
Forum: General Bullet Physics Support and Feedback
Topic: why do btRigidBody objects land on ground on thin edge?
Replies: 3
Views: 32232

Re: why do btRigidBody objects land on ground on thin edge?

I think I have solved the problem for most cases. Actually, I think changing the default values was what actually caused the problem. Mucking around with m_rollingFriction, m_spinningFriction, SleepingThresholds, Damping and DeactivationTime made everything worse. You should leave these at defaults....
by ed_welch
Tue Oct 18, 2022 10:14 am
Forum: General Bullet Physics Support and Feedback
Topic: why do btRigidBody objects land on ground on thin edge?
Replies: 3
Views: 32232

Re: why do btRigidBody objects land on ground on thin edge?

Thanks for you answer drleviathan. I am using normal value for gravity. I tried messing around with the different parameters, but it does not seem to make any difference. I tried modifying m_friction, m_spinningFriction, m_restitution, m_rollingFriction to various values I set setAngularVelocity to ...
by ed_welch
Mon Oct 03, 2022 6:22 pm
Forum: General Bullet Physics Support and Feedback
Topic: why do btRigidBody objects land on ground on thin edge?
Replies: 3
Views: 32232

why do btRigidBody objects land on ground on thin edge?

When I drop objects on the ground I always get objects landing on the thin edge of the object, when it should topple over onto the flat edge. About 30% of the time this happens. Does anyone know a solution to this problem?
by ed_welch
Sat Jul 09, 2022 7:34 pm
Forum: General Bullet Physics Support and Feedback
Topic: crash at btConvexHullShape::localGetSupportingVertexWithoutMargin
Replies: 5
Views: 36987

crash at btConvexHullShape::localGetSupportingVertexWithoutMargin

I tried upgrading my project which was using an old version of bullet (2.88) to the lastest version (3.24) and now I get a crash at btConvexHullShape::localGetSupportingVertexWithoutMargin()

Anyone know what change could have happened to cause this crash?
by ed_welch
Mon Aug 30, 2021 3:56 pm
Forum: General Bullet Physics Support and Feedback
Topic: dropped object does not come to rest on longer edge
Replies: 2
Views: 11463

Re: dropped object does not come to rest on longer edge

Thanks for your answer, drleviathan. Adding small amount of angular velocity seemed to do the trick
by ed_welch
Sun Aug 29, 2021 10:32 am
Forum: General Bullet Physics Support and Feedback
Topic: Object falls a third of its height through the ground
Replies: 11
Views: 46524

Re: Object falls a third of its height through the ground

Try setting a small amount of margin on both objects:
pCollisionShape->setMargin(0.05f);
by ed_welch
Sat Aug 28, 2021 2:11 pm
Forum: General Bullet Physics Support and Feedback
Topic: dropped object does not come to rest on longer edge
Replies: 2
Views: 11463

dropped object does not come to rest on longer edge

I have a problem if a capsule shape object it dropped on to the ground on it's top or bottom side, it comes to rest on the same edge, which is round (because it's a capsule). It should fall over onto its longer edge. I also notice the same problem with btConvexHullShape - the object come to standsti...
by ed_welch
Thu Apr 08, 2021 6:31 pm
Forum: General Bullet Physics Support and Feedback
Topic: inverse kinematics
Replies: 1
Views: 30044

inverse kinematics

A quick question: does bullet include inverse kinematics that could be used to control a skinned mesh?
I.e. it would allow me to enter the joints and constraints of a human skeleton and when I fix the feet to the floor and push down the root node, the knees would bend.
by ed_welch
Thu Aug 02, 2018 4:24 pm
Forum: General Bullet Physics Support and Feedback
Topic: query if a btRigidBody object is already in btDynamicsWorld?
Replies: 1
Views: 7681

query if a btRigidBody object is already in btDynamicsWorld?

Quick question: Anyone know how to query if a btRigidBody object is already in btDynamicsWorld?