README.md

Cython Extension example

This example illustrates how to build a simple python cython extension using cmmcore.

Project structure

A simple python extension structure might look like this:

.
├─── ccx.pyx # Cython source file. 
├─── main.py # Python program.
├─── setup.py # Build script for the extension
└─── requirenments.txt # python requirenments

In this example, there is additionally a build.sh file containing all the commands for building. But since it re-creates a virtual environment, you probably don't want to take it into the actual project.

ccx.pyx

The extension file, contains just one function pyccx, which implements a wrapper over the NURBS two-curve intersection function cmmcore::ccx. In this example, we will not create a wrapper of the cmmcore::NURBSCurve class, so our function will only take control points and degree for each of the curves to be intersected. If you are familiar with cython you can easily extend these definitions.

Build

1. Navigate to the given folder

   cd examples/cython_extension ## If you are in the root of the project

2. Create and activate the virtual environment

   python3 -m venv venv
   source venv/bin/activate

3. Install the necessary dependencies

   python3 -m pip install -r requirenments.txt

4. Build the extension

   python3 setup.py build_ext --inplace

5. Make sure everything works

   python3 main.py

   Output:

   [(0.3237280994653702, 0.22155483439564705), (1.2614987790584564, 0.786673478782177), (2.3095895648002625, 3.0814577788114548), (4.2597944140434265, 6.622736647725105), (2.8862611055374146, 7.53760227560997), (8.019260108470917, 10.729096576571465), (10.308691799640656, 12.926283463835716), (0.06767705082893372, 18.62513067573309), (6.138576149940491, 5.043478101491928)]
   ccx calculated at: 0.5918329999999999 ms. 
   

   0.59 milliseconds - pretty fast for my machine.