Client Side Tree Layout by Emscripten

This project demonstrates how to leverage C++ assets to build an SVG tree visualization on a client's web browser. The following assets are used:

• Data structures by Boost Graph Library.
• Interval tree by Boost ICL.
• Optimization algorithms by DLib.
• Splines by John Burkardt.

The code provides a worker that does the following:

• Initializes a treeish directed acyclic graph data structure.
• Generates a canonical spatial representation of the data structure from a vertex ranking metric.
• Attaches springs within the spatial representation and imposes a central force to the system.
• Iterates the system toward equilibrium.

The worker provides AMD bindings to control the worker from its owner. These bindings have been built with an eye toward generic RPC.

Extra credit:

• Edge targets with multiple parents degenerate the perfectly handled tree to a treeish thing. An edge could be routed efficiently by building a Voronoi diagram from the vertex spatial layout, and then constraining the edge's interior Bezier points to a shortest path in the Voronoi graph. CGAL seems like the path of least resistence--check out this repo for a jump start. Maybe there's a better way?

Rationale

This code resulted from an abandoned attempt under pure Javascript, included in this repository for posterity (I sure don't want it cluttering my computer). When I decided that I needed a segment tree, I tired of the one-off effort. The central focus of this repository is bending Emscripten to the problem.

The following hurdles affected the final solution (expected hurdles that were nonissues have been struck through):

• Marshalling data in and out of the resulting javascript code (in an acceptably literate manner). Workers provide a natural separation.
• Size of the glue code needed to bring together multiple codebases. Both BGL and Dlib are heavily templated, which I hope constitutes a virtue under Emscripten.
• AMDifying the resulting code. I see no value in covering the whole gamut of Javascript imports, since I expect very little glue code required to get things rolling. I'm using AMD alone until a need for some other arises. I've built a Promises interface to access the worker. While it's more code than I care for, a custom DSL could generate the C++ bindings and the AMD boilerplate as a build step--I'm thinking Python's [PLY](http://www.dabeaz.com/ply/ply.html).