cadquery-ocp: Open CASCADE Technology Python Wrapper

7.9.3.1 · active · verified Sun Apr 12

cadquery-ocp provides a low-level Python wrapper for the Open CASCADE Technology (OCCT) 3D geometry kernel, offering thin bindings to almost all OCCT C++ libraries. It is a fundamental dependency for the CadQuery parametric CAD framework and is regularly updated to react quickly to new OCCT releases. The current version is 7.9.3.1.

Warnings

gotcha Direct usage of the OCP (OCCT C++ API) is significantly more verbose and complex than using higher-level libraries like CadQuery. It requires a strong understanding of the underlying Open CASCADE Technology C++ classes and concepts.
Fix: For most parametric CAD tasks, it is recommended to use the CadQuery library (which builds on OCP) for a more Pythonic and fluent API. Only drop down to OCP when direct OCCT access is essential.
gotcha Installation via `pip` can sometimes encounter issues due to complex binary dependencies, especially on less common system configurations or Python versions. `conda` is often recommended for a more robust installation experience, particularly when also installing CadQuery.
Fix: If `pip install cadquery-ocp` fails, try using `conda install -c conda-forge -c cadquery ocp`. Ensure your Python environment meets the required versions.
gotcha The `cadquery-ocp` library has specific Python version requirements (>=3.10, <3.15 for version 7.9.3.1). Installing with an incompatible Python version will lead to installation failures or runtime errors.
Fix: Ensure you are using a compatible Python version, e.g., Python 3.10, 3.11, 3.12, or 3.13 for OCP 7.9.3.1. It is highly recommended to use a virtual environment.

Install

pip install cadquery-ocp PyPI (pip)
conda install -c conda-forge -c cadquery ocp Conda (recommended for CadQuery users)

Imports

BRepPrimAPI_MakeBox
```
from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
```
General pattern: `from OCP.ThePackageName import TheClassName` for direct OCCT API bindings.
gp_Pnt
```
from OCP.gp import gp_Pnt
```
General pattern: `from OCP.ThePackageName import TheClassName` for direct OCCT API bindings.

Quickstart

This quickstart demonstrates how to create a basic 3D shape (a box) directly using the low-level OCP bindings for the Open CASCADE Technology API. It imports specific classes like `BRepPrimAPI_MakeBox` and `gp_Pnt` from their respective OCP packages to construct the shape.

from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
from OCP.gp import gp_Pnt

# Create a 10x20x30mm box starting at (0,0,0)
box_maker = BRepPrimAPI_MakeBox(gp_Pnt(0, 0, 0), 10.0, 20.0, 30.0)
ocp_shape = box_maker.Shape()

# The ocp_shape object can then be used by other OCP functions
# or converted into a CadQuery object for higher-level operations.
# Example (requires CadQuery):
# import cadquery as cq
# cq_box = cq.Shape.cast(ocp_shape)
# print(cq_box.isValid())

print(f"Created OCP shape: {ocp_shape.__class__.__name__}")

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