Real-Time Physics Simulation Forum 2022-03-23T10:51:21+00:00 https://pybullet.org/Bullet/phpBB3/app.php/feed/topic/13407 2022-03-23T10:51:21+00:00 2022-03-23T10:51:21+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=43953#p43953 <![CDATA[Re: Placement of Colliders in MultiBody]]>

Code: 

CompoundShape->addChildShape(transform/*offset*/, CollisionShape);

Statistics: Posted by LukeMurray — Wed Mar 23, 2022 10:51 am

]]> 2022-03-22T14:38:08+00:00 2022-03-22T14:38:08+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=43949#p43949 <![CDATA[Placement of Colliders in MultiBody]]>
I'm creating a MultiBody and I'm having a hard time figuring out whether or not I am actually supposed to have control over where to place the colliders?

To take the MultiDofDemo example provided, in the code there is the following:

Code: 

for (int i = 0; i < pMultiBody->getNumLinks(); ++i){[b]btVector3 posr = local_origin[i + 1] + btVector3(30.f, 1.f, 0.f);////float pos[4]={posr.x(),posr.y(),posr.z(),1};btScalar quat[4] = {-world_to_local[i + 1].x(), -world_to_local[i + 1].y(), -world_to_local[i + 1].z(), world_to_local[i + 1].w()};btCollisionShape* box = new btBoxShape(linkHalfExtents);btMultiBodyLinkCollider* col = new btMultiBodyLinkCollider(pMultiBody, i);col->setCollisionShape(box);btTransform tr;tr.setIdentity();tr.setOrigin(posr);tr.setRotation(btQuaternion(quat[0], quat[1], quat[2], quat[3]));col->setWorldTransform(tr);col->setFriction(friction);pWorld->addCollisionObject(col, 2, 1 + 2);pMultiBody->getLink(i).m_collider = col;[/b]}
What I have found though is once the Collider is set:

Code: 

pMultiBody->getLink(i).m_collider = col;
All the transforms added prior are gone! In fact, I have found the below has the exact same effect:

Code: 

for (int i = 0; i < pMultiBody->getNumLinks(); ++i){btCollisionShape* box = new btBoxShape(linkHalfExtents);btMultiBodyLinkCollider* col = new btMultiBodyLinkCollider(pMultiBody, i);col->setCollisionShape(box);col->setFriction(friction);pWorld->addCollisionObject(col, 2, 1 + 2);pMultiBody->getLink(i).m_collider = col;}
This is currently an issue for me since I have everything working on a MultiBody of my own, however since I am wanting to use capsules I can not rotate them to face the correct way. Am I missing something?

Thanks everyone, any help would be greatly appreciated!

Statistics: Posted by LukeMurray — Tue Mar 22, 2022 2:38 pm

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