Exporting rhino3dm.File3dm to STL in python

Question

I’m using rhino.compute to calculate a mesh.

How could I convert the 3dm decoded mesh to an STL file?

Currently, I can only save it as a 3dm:

import compute_rhino3d.Grasshopper as gh
import rhino3dm

output = gh.EvaluateDefinition(definition_path, trees)
mesh = output['values'][0]['InnerTree']['{0}'][0]["data"]

mesh = rhino3dm.CommonObject.Decode(json.loads(mesh))
doc = rhino3dm.File3dm()
doc.Objects.AddMesh(mesh)
doc.Write("model.3dm", version=0)

Thank you very much!

Answer 1

You can use Rhino.RhinoDoc.WriteFile to write to all file types that rhino conventionally supports for exporting.

def ExportStl():
    
    #Path to save File.
    filepath = r"C:\Temp\TestExport.stl"
    
    #Create write options to specify file info.
    write_options = Rhino.FileIO.FileWriteOptions()
    
    #Export all geometry, not just selected geometry.
    write_options.WriteSelectedObjectsOnly = False

    #Write File.
    result = Rhino.RhinoDoc.ActiveDoc.WriteFile(filepath, write_options)

ExportStl()

In this case, I'm using the Rhino 'RunPythonScript' command with the open ActiveDoc but in your example, you could use doc.WriteFile(filepath, write_options) instead.

When you first run this, there is a .stl export dialogue that has export options. This window can be suppressed to the command line with write_options.SuppressDialogBoxes = True.

Or you can check the 'Always use these settings. Do not show this dialogue again.' option and it will not interrupt export in the future.

Your example suggests you may be working in a headless environment so I'm not sure how these dialogues would be handled in that scenario.