A margin for the visible boundaries of the child.
Any transformation that results in the viewport being able to view outside of the boundaries will be stopped at the boundary. The boundaries do not rotate with the rest of the scene, so they are always aligned with the viewport.
To produce no boundaries at all, pass infinite EdgeInsets, such as
No edge can be NaN.
Defaults to EdgeInsets.zero, which results in boundaries that are the exact same size and position as the child.
final EdgeInsets boundaryMargin;