rigid_body_gravity

Gravity is such a common force that it is implemented as a special case (even if it could easily be implemented by the user using force application). The gravity is given by the field RapierConfiguration::gravity of the resource RapierConfiguration and can be modified at will. Note however that a change of gravity won't automatically wake-up the sleeping bodies so keep in mind that you may want to wake them up manually before a gravity change.

note

Because fixed and kinematic bodies are immune to forces, they are not affected by gravity.

info

A rigid-body with no mass will not be affected by gravity either. So if your rigid-body doesn't fall when you expected it to, make sure it has a mass set explicitly, or has at least one collider with non-zero density attached to it.

It is possible to change the way gravity affects a specific rigid-body by setting the rigid-body's gravity scale to a value other than 1.0. The magnitude of the gravity applied to this body will be multiplied by this scaling factor. Therefore, a gravity scale set to 0.0 will disable gravity for the rigid-body whereas a gravity scale set to 2.0 will make it twice as strong. A negative value will flip the direction of the gravity for this rigid-body.

This gravity scale factor can be set when the rigid-body is created or after its creation:

/* Set the gravity scale when the rigid-body is created. */
commands.spawn(RigidBody::Dynamic).insert(GravityScale(2.0));

/* Set the gravity scale inside of a system. */
fn modify_body_gravity_scale(mut grav_scale: Query<&mut GravityScale>) {
    for mut grav_scale in grav_scale.iter_mut() {
        grav_scale.0 = 2.0;
    }
}