Rigid body motion stops abruptly

[Netzwerk2]

When applying a small velocity to a rigid body, it will stop moving after a few seconds (the same happens with rotation). Here's a minimal example to reproduce

use bevy::prelude::shape::Cube;
use bevy::prelude::*;
use bevy_rapier3d::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugin(RapierPhysicsPlugin::<NoUserData>::default())
        .insert_resource(RapierConfiguration {
            gravity: Vec3::ZERO,
            ..default()
        })
        .add_startup_system(setup)
        .run();
}

fn setup(mut commands: Commands, mut meshes: ResMut<Assets<Mesh>>) {
    commands
        .spawn_bundle(PbrBundle {
            mesh: meshes.add(Cube::default().into()),
            ..default()
        })
        .insert(RigidBody::Dynamic)
        .insert(Velocity {
            linvel: Vec3::new(0.0, 0.2, 0.0),
            // angvel: Vec3::new(0.2, 0.0, 0.0),
            ..default()
        })
        .insert(AdditionalMassProperties::MassProperties(MassProperties {
            mass: 1.0,
            principal_inertia: Vec3::splat(1.0),
            ..default()
        }));

    commands.spawn_bundle(Camera3dBundle {
        transform: Transform::from_xyz(3.0, 2.0, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
        ..default()
    });
}

[sebcrozet]

Hi! This is the expected behavior caused by the automatic sleeping system. If a rigid-body moves slowly during some period of time, it will be stopped and "put to sleep" (i.e. stop being simulated until it is moved again or hits something) to save computation times.

You can increase the movement threshold for that sleeping system by inserting the Sleeping component (to the same entity as the rigid-body) with custom threshold values; your you can disable sleeping altogether for that rigid-body.

[Netzwerk2]

That explains it. Thank you!