I have as an input a 2D polygon with holes, and I need to find it's straight skeleton, like in the picture:
http://www.cgal.org/Manual/3.2/doc_html/cgal_manual/Straight_skeleton_2/exterior_skeleton.png
Maybe there is a good Java library for it?
And if not, can you point me to the good explanation of the algorithm, so I could implement it myself? (I haven't found good resources on Google)
I wrote this a little while back. Not sure if it's robust enough.
https://github.com/twak/campskeleton
(edited for 2018...)
See http://www.sable.mcgill.ca/~dbelan2/roofs/roofs.html which contains an applet.
Edit:
Ah. I see that "Straight Skeleton" is a technical term. The wikipedia article references several algorithms. Have you looked at those?
As I understand it, you have a (convex?) polygon. From it, you subtract 1 or more (potentially non-convex) polygons. You want to turn the result into a set of polygons without holes. Are there extra rules that you're trying to apply?
I have a hard time coming up with a set of rules from the example that you provided. The outer polygons are non-convex; so it doesn't seem like you're trying to find a convex set to represent the result (which is a relatively common task).
If you could use the breakdown shown below, the algorithm is pretty simple. Can you clarify?
You may be able to use the JTS Topology Suite. It is a very capable library that I've used on a number of projects - never for straight skeleton, but it may be possible.
Can I ask u what is your purpose for finding Straight skeleton? Is it personal or commercial? I would be interested in knowing how you r using it to solve real time problems? I do have a java library that does that. My algorithm is listed here http://web.stcloudstate.edu/rsarnath/skeleton/definition.htm