/// <summary>Adds the specified component to the specified index.</summary>
/// <param name="component">The component to add.</param>
/// <param name="index">The index.</param>
private void AddIndex(IIndexable component, int index)
{
// Ignore invalid ids, which can be used to disable components.
if (index < 0)
{
return;
}
this[index].Add(component.ComputeWorldBounds(), component.Id);
_changed[index].Add(component.Id);
}