Extract polygon-coordinates from citygml data using citygml4j

Question

My question is closely related to Extract geometry from citygml data using citygml4j

I have a citygml file with buildings and I need to extract the coordinates of each roof surface. I use the open source library citygml4j. My code is almost the same as in the link, but I am stuck at the line:

AbstractRing exteriorAbstractRing = polygon.getExterior().getRing();

How do you extract the coordinates of the polygon-geometry from here?

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Found the solution with help from @JulianRosse. There are some solution if is a LinearRing, e.g.:

((LinearRing)polygon.getExterior().getRing()).toList3d()

Answer 1

Take a look at the LinearRing class and casting to that. Calling .toList3d() on a LinearRing will return a List of the coordinates. I would use an IDE with code-completion to help with navigating the citygml4j model.