Cut mesh with complex 3D shape

Hi there,

I want to have a complex 3D shape cut out of a mesh.

Is it possible to set multiple points on a mesh (on different sides), connect them as a smooth curve and then cut the mesh at this curve.
I already tried to use a C# script that projects a curve on a mesh, however the shape of the curve will not remain the same. Thereby when I want to cut the mesh at this curve, I only knows te option where it creates a patch that still be very curved (see image for part of code). The shape should also contain a straight segment at the back.

Or does someone has another idea how I can do this…?

Thankyou in advance!

Schermafbeelding 2021-11-04 om 13.41.10

In regular Rhino I would:

Use InterpCrv with OnMesh to create the mesh using points on the mesh.

Pull the curve onto the mesh surface. Pull is different than Project. Pull moves the curve to the closest onto the closest faces of the mesh. (Project works in a straight direction.)

MeshTrim the mesh with the pulled curve as the cutting tool.

Pulling the curve onto the mesh, not projecting the curve, is the key.

Thankyou for your quick respons, I will try that! But can you maybe help me out with a couple things:

  • The output: KangarooSolver.Goals.Onmesh What does that mean and how can I fix that?
  • How do you select the outer surface of a mesh?
  • Which MeshTrim option should I use? I only see Mesh trim Twisted boxes, trim solid, trim breps. Or is it within a special plugin?

Sorry I’m quite new to Grasshopper…

Thankyou in advance!

You’re much more likely to get help if you post a file with your geometry and the code you are trying that isn’t working.


I only use Rhino, not Grasshopper.

Do you only use Grasshopper, and not Rhino directly?

Oh, no I need it working in Grasshopper…

Then you need to find the Grasshopper equivalent to the Rhino Pull command.