Requires:

• Windows

• Python 3

• pythonnet>=3.0.0

• Autodesk Inventor (2020+)

Features:

• Dynamic Inventor version detection (picks the newest installed version)

• Lazy loading of the Interop assembly, so modules can be imported in any order

• Efficient objects iteration and searching

• .NET/CLR interface to Inventor API

• Document type casting (Part, Assembly, Drawing, Presentation)

• Geometry casting for edges and faces (LineSegment, Circle, Plane, Cylinder, …)

• Extension methods on Inventor objects, e.g. edge.cast_edge_geometry()

• Custom error handling with specific exceptions

• Support for connecting to active Inventor instances or creating new ones

Installation:

pip install pysharpinventor

For development, install from a clone in editable mode:

git clone https://github.com/Nandhakumarpro/PySharpInventor.git
cd pysharpinventor
pip install -e .

Usage Example:

from pysharpinventor import Inventor, InventorInterop

# Connect to active Inventor instance
inv = Inventor()

# Or create new instance if Inventor is not running
inv = Inventor(create_if_not_exists=True)

# Or point at a specific Inventor Interop DLL
inv = Inventor(inventor_path=r"C:\Program Files\Autodesk\Inventor 2025\Bin\Public Assemblies\Autodesk.Inventor.Interop.dll")

# Access active document
doc = inv.doc

# Cast document to specific type
part_doc = inv.cast_document(doc, InventorInterop.PartDocument)

# Or auto-detect document type
casted_doc = inv.cast_document(doc)

The Inventor object

Inventor(create_if_not_exists=False, visible=True, inventor_path=None)

• create_if_not_exists - start a new Inventor if none is running.

• visible - whether a newly started Inventor window is visible.

• inventor_path - path to Autodesk.Inventor.Interop.dll. When omitted, the newest installation under C:\Program Files\Autodesk\Inventor * is used.

Properties and methods:

• inv.app (alias inv.Application) - the Inventor.Application. Connects on first use.

• inv.doc (alias inv.ActiveDocument) - the active document.

• inv.cast_document(document, target_type=None) - cast a document to PartDocument, AssemblyDocument, DrawingDocument or PresentationDocument. Without target_type the type is detected from document.DocumentType.

InventorInterop

InventorInterop is the Inventor .NET namespace (Inventor.* in C#). Use it for classes and enums:

from pysharpinventor import InventorInterop

InventorInterop.PartDocument
InventorInterop.SurfaceTypeEnum.kPlaneSurface

It is safe to import anywhere, at any time. The Interop assembly is loaded the first time an attribute is accessed. If you need a custom DLL path, create Inventor(inventor_path=...) before touching InventorInterop; once loaded, the assembly cannot be swapped for another version in the same process.

Geometry casting

Edge.Geometry and Face.Geometry are returned by the API as a bare System.__ComObject. The helpers in pysharpinventor.geometry read the geometry type and cast it to the matching Inventor class:

from pysharpinventor.geometry import cast_edge_geometry, cast_face_geometry

body = part_doc.ComponentDefinition.SurfaceBodies[1]

curve_type, curve = cast_edge_geometry(body.Edges[1])
if curve_type == InventorInterop.CurveTypeEnum.kCircleCurve:
    print(curve.Radius)

surface_type, surface = cast_face_geometry(body.Faces[1])
if surface_type == InventorInterop.SurfaceTypeEnum.kCylinderSurface:
    print(surface.Radius, surface.AxisVector.X, surface.AxisVector.Y, surface.AxisVector.Z)

For unknown types (kUnknownCurve / kUnknownSurface) Inventor usually cannot provide the geometry; the helpers then return None as the geometry. Use edge.Evaluator / face.Evaluator for such entities.

get_edge_curve_type(edge) and get_face_surface_type(face) return only the type.

Extension methods

After import pysharpinventor, the geometry helpers are also available as methods on Edge, EdgeProxy, Face and FaceProxy objects, similar to C# extension methods:

curve_type, curve = body.Edges[1].cast_edge_geometry()
surface_type, surface = body.Faces[1].cast_face_geometry()

You can attach your own functions the same way:

from pysharpinventor._interop import register_extension

def area(face):
    return InventorInterop.Face(face).Evaluator.Area

register_extension('Face', 'area', area)
body.Faces[1].area()

Things to know

• Units. The Inventor API works in internal units: centimetres for length and radians for angles, regardless of the document’s display units.

• Indexing is 1-based. body.Faces[1] is the first face.

• Iterating collections returns untyped objects. for e in body.Edges yields System.__ComObject values, which do not have the typed properties or extension methods. Cast them first: InventorInterop.Edge(e). Indexing (body.Edges[1]) returns typed objects.

• Plane normals may point into the solid. Plane.Normal is not guaranteed to be the outward direction of a face. Flip it when face.IsParamReversed is True.

• .NET API names differ from VBA in places. For example, use ExtrudeFeatures.Add(definition) rather than AddByDefinition.

Errors

• InventorVersionNotFoundError - the Interop DLL could not be found. Pass inventor_path.

• InventorConnectionError - pythonnet is missing, the DLL failed to load, or Inventor is not running (and create_if_not_exists is False).

Both can be imported from pysharpinventor.

Examples

examples/hello_world.py creates a new part containing a 5 cm cube and prints each face’s type, area and outward normal. Run it from the repository root:

python -m examples.hello_world

Links

• Source code at GitHub