After an email exchange with the lead author, I just rendered one of their demo datasets using my Datoviz GPU rendering library [1]. It looks nice and it's quite fast. I'm just rendering uniform triangles using standard 3D rasterization.
Strange that it works for me in various browsers while I'm logged out of GitHub. Might be a caching thing. Anyway, I reuploaded it elsewhere: https://imgur.com/Qc8r15I