# Trimmed Surface problem

I have a simple trimmed surface from a subd and need to make a space truss structure ignoring the trimmed areas, I have already shrunk the edges but GH is still populating the panels when I use Lunchbox onto the trimmed areas.

Does anyone know how to solve this issue or guide to find a answer?

Initial SubD with the trimming shapes

Final trimmed surface

Surface with the space truss structure

Trimmed Suface problem.gh (31.2 KB)

Hey @mauriciovb - no matter how simple, clean, and beautiful your trimmed shape is itâ€™s still trimmed and lunchbox wants untrimmed so youâ€™ll continue to get the truss system drawn on what it considers the untrimmed surface - your situation calls for something more involved and not something a plug-in will give you - something exists out there I assume, most likely via code - I notice you were tri-remeshing your shape, does this mean youâ€™d also consider doing a space frame using the mesh triangles?

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there are multiple topics on this f.e.

but as far is i know you have to find a method to remodel your geometry as a clean surface.
This would be my attempt:

Trimmed Suface problem.gh (37.8 KB)

Unfortunatly i could not finish it but maybe some oneelse will take over but you could sweep the outer edge naked edges with the plane brep intersection as rail (blue) or creat a ruled surface, loft whatever from the brep intersections (green). the problematic part marked red . hopefully someone has a good idea how to solve it

EDIT

this probably is not working with the space truss because it would creat multiple surfaces anyways maybe this triggers ideas for working solutions

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Thatâ€™s very easy via code. Notify if you want an entry Level C# on that.

But trusses without clash detection (sleeves, nuts, bolts, tubes etc etc) is a 100% nothing thing (that is done via VV, VE, EV connectivity and using solely trigonometry). Anyway a truss without connectivity is 10000% useless in real-life.

That said a W truss (say a MERO) with quad nodes in top/bottom requires a planarity check (i.e. checking min dist between diagonals VS some rational value) â€¦ if the related envelope follows the quads (i.e. is not done via triangular modules). Plus thereâ€™s the structure rigitify little thing.

https://www.setareh.arch.vt.edu/safas/010_system_04_mero.html

Plus if the â€śrealisticâ€ť members (i.e. going from abstract axis to Breps + some detail) are many â€¦ one should use Instance Definitions otherwise â€¦ well â€¦ you can imagine what would happen.

In general have in mind that solving a real-life truss that follows some non planar Surface/BrepFace (or some â€śequivalentâ€ť Mesh) is impossible without code.

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