Roberto Toro, March 2019

This is a javascript version of the awesome implementation in 88 lines of c++ of the Moving Least Squares Material Point Method, by Yuanming Hu.

The original repository is https://github.com/yuanming-hu/taichi_mpm, and the c++ code can be directly downloaded from http://bit.ly/mls-mpm88. This link contains 2 files: taichi.h, with linear algebra and helper functions; and mls-mpm88.cpp with the actual implementation of the material point method.

In this javascript version, the linear algebra functions are in the algebra.js file, and the MPM code in the mls-mpm.js file (with the 88 removed, because now it's 148 lines... but there's much more comments, so we're still good).

A main tricky thing in the translation, which still is not completely solved, is that matrices in Taichi are coded transposed. In the translation, there's still a mix of functions that work transposed (svd, polar_decomp, mulMatVec), and those that don't. That makes some parts of the code a bit convoluted. Ideally, I'd like to move all the code to standard non-transposed matrix encoding.

• Thanks to Yuanming Hu for making the C++ code available and for help on understanding it.
• Thanks to Kevin Chapelier for making the javascript code x5 faster and reducing the initialisation from several seconds to barely noticeable.