rigid_body_position

The position of a rigid-body represents its location (translation) in 2D or 3D world-space, as well as its orientation (rotation). Both are stored in the standard Bevy Transform component.

The position of a rigid-body can be set when creating it. It can also be set after its creation as illustrated below.

warning

Directly changing the position of a rigid-body is equivalent to teleporting it: this is a not a physically realistic action! Teleporting a dynamic or kinematic bodies may result in odd behaviors especially if it teleports into a space occupied by other objects. For dynamic bodies, forces, impulses, or velocity modification should be preferred. For kinematic bodies, see the discussion after the examples below.

Example 2D

commands
    .spawn(RigidBody::Dynamic)
    .insert(Transform::from_xyz(0.0, 5.0, 0.0))

/* Change the position inside of a system. */
fn modify_body_translation(mut positions: Query<&mut Transform, With<RigidBody>>) {
    for mut position in positions.iter_mut() {
        position.translation.y += 0.1;
    }
}

Example 3D

commands
    .spawn(RigidBody::Dynamic)
    .insert(Transform::from_xyz(0.0, 0.0, 0.0))

/* Change the position inside of a system. */
fn modify_body_translation(mut positions: Query<&mut Transform, With<RigidBody>>) {
    for mut position in positions.iter_mut() {
        position.translation.y += 0.1;
    }
}

In order to move a dynamic rigid-body it is strongly discouraged to set its position directly as it may results in weird behaviors: it's as if the rigid-body teleports itself, which is a non-physical behavior. For dynamic bodies, it is recommended to either set its velocity or to apply forces or impulses.

For velocity-based kinematic bodies, it is recommended to set its velocity instead of setting its position directly. For position-based kinematic bodies, it is recommended to modify its Transform (changing its velocity won’t have any effect). This won't teleport the kinematic body immediately: the modified Transform is used as its next kinematic position, which lets the physics engine compute the fictitious velocity of the kinematic body for more realistic interactions with other rigid-bodies.