New rigid-body position doesn't get effected by gravity

[Lil_Margin]

Hey,
I am new to the Bullet Physics Engine but after following the "Bullet Hello World Tutorial" i got some basic understanding of how Bullet works.
I have a ball/sphere rigid-body that falls to a plane nicely with gravity but when i reposition the sphere rigid-body the rigid-body doesn't get effected by the world gravity.
I am using this code in my keyboard key to reposition the sphere rigid-body

Code: Select all

            btVector3 oldorigin = trans.getOrigin();
            trans.setOrigin(btVector3(0,50,0));
            fallRigidBody->getMotionState()->setWorldTransform(trans);
            fallRigidBody->setCenterOfMassTransform(trans);

when the program begins the sphere rigid-body position goes from 50 to 0 (cause of gravity) but when i reposition the rigid-body it stays at 50
Am i missing something in my code or am i doing the reposition completely wrong?
Thanks in advanced.

[Lil_Margin]

I notice that it works until my sphere hits the plane, when it hits the plane it seems like gravity doesnt effect my sphere rigidbody anymore.

[Erwin Coumans]

You might have to activate the rigid body:

Code: Select all

body->activate();

Hope this helps,
Erwin

[Lil_Margin]

Thanks it works, so i guess when a dynamic rigid-body collides with a static object it deactivates, or am i wrong?