btTransform operator* on btVector3 missing from IDL // cannot applyForce local/relative to btRigidBody

[ricksterhd123]

Been trying to applyForce relative to a rigidbody, if anyone has any ideas how I may do this then please let me know. Anyway, after trying to follow the solution from this ancient forum post: https://pybullet.org/Bullet/phpBB3/viewtopic.php?t=2366 I've found this:

btVector3 relativeForce = btVector3(0,10,0);
btTransform* boxTrans;
boxRigidBody->getMotionState()->getWroldTransform(boxTrans);
btVector3 correctedForce = (boxTrans * relativeForce) - boxTrans.getOrigin();
boxRigidBody->applyCentralForce(correctedForce);

If you look in
https://pybullet.org/Bullet/BulletFull/classbtTransform.html
then you see that
btVector3 operator* (const btVector3 &x) const
is needed to achieve it, however i cannot find this definition in the IDL anywhere.

Please could someone look into fixing this? Does anyone have an alternative solution, I just don't want to waste time migrating to another physics library...

[ricksterhd123]

For anyone looking how to apply a force local/relative to btRigidBody in ammo.js, here's how:
let transform = new Ammo.btTransform();
body.getMotionState().getWorldTransform(transform);
let relativeForce = new Ammo.btVector3(0,0, 1000);
let relativeTransform = new Ammo.btTransform();
relativeTransform.setOrigin(relativeForce);
let relativeForce = (transform.op_mul(relativeTransform)).getOrigin();
body.applyForce(relativeForce, transform.getOrigin());

Set the relativeForce which is a btVector3 into a btTransform using btTransform.setOrigin, then use op_mul and retrieve the resulting btVector3 using btTransform.getOrigin

I'm now going to close the issue, I hope people will find this if anyone has the same trouble I did.

[marlonicus]

Thanks @ricksterhd123! Exactly the problem I was struggling with... And thank you again for leaving a breadcrumb to this page on a 10-year-old thread, the internet needs more heroes like you 👏

[kmindspark]

Same here! Thanks @ricksterhd123

[AndreyNesterenko2020]

If you are using three JS, just do:
var temporaryEuler = new THREE.Vector3(1,0,0).applyQuaternion(objThree.quaternion); objAmmo.setLinearVelocity(new Ammo.btVector3(temporaryEuler.x, temporaryEuler.y, temporaryEuler.z));
Where objAmmo is the ammo object and objThree is the three js object.
The above code will make the object go forward. @ricksterhd123

[dataexcess]

@ricksterhd123 solution is not working for me. Seems I can only use setLinearVelocity. Which is not what I want, because then gravity is not working.