I couldn't find any plane-fitting algorithms for Processing, so I wrote my own.
Released under GPL-3.0-or-later.
There are two Processing sketches in this repo: one that fits a plane from the Kinect V2 point cloud using the KinectPV2 library, and one that fits a plane from a generated point cloud.
The algorithm is currently a RANSAC with a fixed number of iterations.
Enjoy!