how to decide outside walls

[WenFai]

Another question :
we want to select the outside walls of a house.
As we want to build a community with several top buildings, we draw each building with just one level,then the plugin extend it to a building. we don't need the walls inside the building, we just use the outside walls to build it.It could help to reduce the stress for the program to show the home view.
But the walls is not just a line, it could be a circular arc with a property named arcExtent.
Is there any method can help with it in API? or any other ideas?

Thanks

[Puybaret]

There's no method in the program to detect outside walls.
Maybe you could reuse [font=courier new]wallsAreaCache[/font] handled in [font=courier new]PlanController[/font] to get its exterior path(s) using [font=courier new]getAreaPoints[/font] in [font=courier new]Object3DBranch[/font]. The exterior walls should be the ones that intersect with this exterior path, but that won't work if an interior wall touches the border of an exterior wall.