Function on_exit_constant 

pub fn on_exit_constant(
    cmd: Commands<'_, '_>,
    q_nodes: Query<'_, '_, &Transform, With<TrackNode>>,
    cursor_pos: Res<'_, CursorPos>,
    assets_manager: Res<'_, AssetsManager>,
    from_node_type: ResMut<'_, FromNodeType>,
    meshes: ResMut<'_, Assets<Mesh>>,
)

System that reacts to exits from constant step and spawns the virtual segment