This is an implementation of the Quickhull 3d algorithm which constructs the convex hull of a set of points, and a visualization of the algorithm steps using THREE.js. It is not a library, but could be refactored into one.
Live Demo: http://ottoallmendinger.github.io/js-quickhull3d/
Annotated Source: http://ottoallmendinger.github.io/js-quickhull3d/docs/qhull.html
MIT Licensed