collider_position

The position of a collider represents its location (translation) in 2D or 3D world-space as well as its orientation (rotation). Both are combined in a Bevy Transform component.

warning

Please read carefully the paragraph after the next example. It explains how the collider position (and the action of setting this position) behaves differently when it is attached to a rigid-body.

It is possible to set this position when the collider is created or after its creation:

Example 2D

/* Set the collider position when the collider is created. */
commands
    .spawn(Collider::cuboid(0.5, 0.5))
    .insert(Transform::from_xyz(1.0, 2.0, 0.0));

/* Set the collider position inside of a system. */
fn modify_collider_position(mut positions: Query<&mut Transform, With<Collider>>) {
    for mut position in positions.iter_mut() {
        position.translation.x = 2.0;
    }
}

Example 3D

/* Set the collider position when the collider is created. */
commands
    .spawn(Collider::cuboid(0.5, 0.5, 0.5))
    .insert(Transform::from_xyz(1.0, 2.0, 3.0));

/* Set the collider position inside of a system. */
fn modify_collider_position(mut positions: Query<&mut Transform, With<Collider>>) {
    for mut position in positions.iter_mut() {
        position.translation.x = 2.0;
    }
}

If a collider is attached to a rigid-body, its position is automatically updated by the physics pipeline when a rigid-body is moved by the physics pipeline. If a change to the rigid-body position is made by the user then the collider position will be updated during the next timestep.

Therefore, if the collider is attached to a rigid-body through a child entity, setting its Transform will modify the position of the collider relative to the rigid-body it is attached to (if the collider is on the same entity as the rigid-body, its Transform is the one of the rigid-body):

Example 2D

// Attach the collider to the rigid-body. The collider is attached as its
// children, so the collider’s `Transform` components sets its position
// relative to the parent rigid-body.
commands
    .spawn((RigidBody::Dynamic, GlobalTransform::default()))
    .with_children(|children| {
        children
            .spawn(Collider::cuboid(0.5, 0.5))
            .insert(Transform::from_xyz(1.0, 2.0, 0.0));
    });

Example 3D

// Attach the collider to the rigid-body. The collider is attached as its
// children, so the collider’s `Transform` components sets its position
// relative to the parent rigid-body.
commands
    .spawn(RigidBody::Dynamic)
    .with_children(|children| {
        children
            .spawn(Collider::cuboid(0.5, 0.5, 0.5))
            .insert(Transform::from_xyz(1.0, 2.0, 0.0));
    });