occ_gordon: A Curve Network Interpolation Library for OpenCASCADE (OCCT)

occ_gordon is a lightweight C++ and python library that implements curve network interpolation using B-spline surfaces within the OpenCASCADE (OCCT) framework.

OCCT lacks built-in support for Gordon surface interpolation, which is a method for interpolating arbitrary large curve networks. This library was developed to provide this functionality, enabling engineers and developers to create smooth, accurate surfaces from interconnected curves in OCCT.

What is a Curve Network?

A curve network is a collection of interconnected curves that define the structural framework or "skeleton" of a surface or shape. By interpolating a curve network, complex surfaces can be accurately created.

Key Features ⭐

• ✨ Gordon Surface Interpolation: Implements the Gordon surface interpolation method, a generalization of the Coons patch, ideal for generating smooth B-spline surfaces from an arbitrary number of profile and guide curves.
• 🔧 Curve Network Reparametrization: Compared to other implementations, occ_gordon reparametrizes the curve network if necessary to ensure proper interpolation of the curves.
• 🤝 OpenCASCADE Integration: Fully integrated with OpenCASCADE, ensuring compatibility with OCCT-based projects.
• 🐍 Python Support: With Python bindings, occ_gordon can be seamlessly integrated with pythonocc, the Python interface for OCCT.
• 🚀 Lightweight: Based on a streamlined, minimal version of the TiGL library, focusing solely on curve network interpolation using B-splines. No other dependencies than OCCT.
• 🔓 Open Source and Apache Licensed: Available under the permissive Apache 2.0 license, making it suitable for both personal and commercial use.

About the Gordon Surface Method

The Gordon surface interpolation method was first published by W.J. Gordon in 1969. It allows for surface generation through the interpolation of an arbitrary number of guide and profile curves using B-splines. It extends the Coons patch method to more complex curve networks, making it versatile tool for surface modeling in 3D CAD applications.

Usage Example

To use the occ_gordon library, include the header file <occ_gordon/occ_gordon.h>. The main function for curve network interpolation is occ_gordon::interpolate_curve_network.

#include <occ_gordon/occ_gordon.h>

std::vector<Handle(Geom_Curve)> vcurves, ucurves;

// Create the curve network
...

double inters_tol = 1e-4; // distance, in which the curves need to intersect

auto surface = occ_gordon::interpolate_curve_network(ucurves, vcurves, inters_tol);

This example demonstrates how to interpolate a curve network using a B-spline surface with a specified intersection tolerance.

Building

To build occ_gordon, you'll need a recent version of CMake (3.15 or higher) and a working installation of OpenCASCADE.

cmake -S . -B build -DOpenCASCADE_DIR=<path/to/cmake/opencascade> -DCMAKE_INSTALL_PREFIX=<path/to/install>
cmake --build build
cmake --build build --target install

License

occ_gordon is licensed under the Apache 2.0 License, making it free to use, modify, and distribute in both personal and commercial projects.

Citing

This algorithm was originally developed as part of the TiGL library. If you use the occ_gordon library in your work, please cite the following paper:

Siggel M. et. al. (2019), TiGL: An Open Source Computational Geometry Library for Parametric Aircraft Design

@article{siggel2019tigl,
	title={TiGL: an open source computational geometry library for parametric aircraft design},
	author={Siggel, Martin and Kleinert, Jan and Stollenwerk, Tobias and Maierl, Reinhold},
	journal={Mathematics in Computer Science},
	volume={13},
	number={3},
	pages={367--389},
	year={2019},
	publisher={Springer},
    doi={10.1007/s11786-019-00401-y}
}