topic Re: Minimal working example of creating a Sweep with a Guide Surface through the Python API in Fusion API and Scripts Forum

Minimal working example of creating a Sweep with a Guide Surface through the Python API

davemurrayrust — Fri, 06 Feb 2026 12:57:42 GMT

I'm trying to create a Sweep programatically. I can't make sense of the docs - partly due to the split between python and C++ and the difficulty of debugging, but also partly as it's a bit confusing. The code is in flux at the moment, but it's roughly along the lines of:

# This works fine, it's making a Surface Loft, shows up orange in the timeline loft_body = loft_feats.add(loft_input) ... sweep_input = sweeps.createInput(profile, path, op) sweep_input.guideSurfaces = loft_body.bodies.item(0) sweep_input.distanceOne = 1.0

If I run it, it's a C++ type error on line 5 (which I can't copy paste from the dialog 😕 )

What *should* I be passing in? And more generally, how should I figure it out?

As a side note - how do I get access to the errors and output logs of Scripts? The online docs (https://help.autodesk.com/view/PLM/ENU/?guid=DEV-ERROR-TRACKING) say there should be a yellow warning icon next to the script, but that doesn't match the current UI

Re: Minimal working example of creating a Sweep with a Guide Surface through the Python API

jeff_strater — Fri, 06 Feb 2026 18:53:42 GMT

I think the problem is that you are passing in a Body. Instead, what appears to be needed is an array of BRepFace. This is consistent with the UI - guide surface is a face selection.

SweepFeatureInput.guideSurfaces Property

Re: Minimal working example of creating a Sweep with a Guide Surface through the Python API

davemurrayrust — Fri, 06 Feb 2026 19:45:11 GMT

Thanks - and sorry to be dim, but how do I get that from the Body? It's a Surface Loft, so it should be the right form in there somewhere - I can use the output to make a surface sweep through the UI - but I can't figure out the translation steps. I tried looking across the object hierarchy in the API docs, but it wasn't immediately apparent.

Re: Minimal working example of creating a Sweep with a Guide Surface through the Python API

jeff_strater — Sat, 07 Feb 2026 00:36:37 GMT

I'm a little out of my depth here, but, from a BRepBody, you can call the faces() property: BRepBody.faces Property . This returns a BRepFaces object, which is a collection of BRepFace. I think this is different than what Sweep requires (an array of BRepFace). Here is a code snippet from google that claims to show how to convert this:

import adsk.core, adsk.fusion, adsk.cam, traceback

def run(context):
ui = None
try:
app = adsk.core.Application.get()
ui = app.userInterface
design = app.activeProduct

# Assume a body is selected
selectedBody = ui.activeSelections.item(0).entity

# Get the BRepFaces collection
facesCollection = selectedBody.faces

# Convert BRepFaces collection to an array (list) of BRepFace
facesArray = []
for face in facesCollection:
facesArray.append(face)

# Example: Access the first face in the array
if len(facesArray) > 0:
firstFace = facesArray[0]
app.log(f'Found {len(facesArray)} faces. First face ID: {firstFace.tempId}')

except:
if ui:
ui.messageBox('Failed:\n{}'.format(traceback.format_exc()))

Re: Minimal working example of creating a Sweep with a Guide Surface through the Python API

rosie_lucas1 — Mon, 09 Feb 2026 19:54:50 GMT

Hello @davemurrayrust ,

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Rosie| Community Manager