Region Difference: How to know what curves are cut?

Hello Rhino Community, I have a set of closed curves that are subtracted with a region and I want to know which curves from the original list are actually subtracted. It is because the output curves is now greater than the original list, naturally it’s because some curves are split into 2 regions. Basically I want to know which output curves come from the original closed curve. Is there a way to do this?

Region Difference - Find What Curves Are (39.7 KB)

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Region Difference - Find What Curves Are (48.7 KB)

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It works. Thank you so much @HS_Kim . :smiley: Is there a conceivably quicker way to do this? It takes more or less , a second for this to process. I want to implement this on a custom script of instancing panels. Basically my script aims to :

  1. Distribute 1 modular block to all the planes of the Panels.
  2. Cull all the blocks that will be affected by the void/cutting curves because as they’ll become irregularly shaped when cut.
  3. Sort and group the Unaffected Panels versus the Affected Panels.
  4. Apply further set creation on the Affected panels to know which are modular in That group.
  5. Culling of the Unique, modular Affected Panels
  6. Deconstructing & Trimming the Unique modular Affected Panels’ geometry via Elefront
  7. Creating new Blocks from the cut geometry
  8. Finally redistributing them to the base planes of it’s original block.

I hope you would comment on this to guide me on whether I’m in the right direction or if there is a vastly simpler approach to this. Anyway I just want to say that I’ve been following you and many of your solutions in the forum for a while and I think you’re the best Scripter out there :smiley:

Panelization Instancing (101.1 KB)