Grasshopper Split Brep order of returned surfaces

I have a question about the order GH returns splitted Breps.

I would like to subtract (dispatch) the splitted Surfaces which are inside the solid.
The (green) solid is the cutter and three planar Surfaces are being splitted.

I hoped that the order of splitted Surfaces was the same so i could use List Item or Cull Patern to subtract the Surfaces inside the solid, but this is not the case.

The vertical Surfaces show that the 1st item is within the solid and the horizontal Surfaces shows that the 2nd item is within solid.

I do not fully understand this order of numbering. Can someone explain this to me?

How can i determine which surface is within the solid? and what if the surface has no cutting edges with the solid? is there a function iā€™m missing?

Thank you in advance!


you can find centroids of splitted surfaces and test them for Brep inclusion via Point in Brep. Then you can cull them.

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Thank you so much for the fast reply ! This solution works for me :slight_smile:

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