Orbitals, Particles, a Font, and some Sheeple

2010.04.29 in code, school, and typography

Apparently the semester's nearly over, or so I've been told (repeatedly. naggingly.)! In any case, I've gotten a lot more done on some things than I expected, and a lot less on others... it's always hard to predict how the semester will go.

A Font

For Typography, I've been working on the font + renderer + autokerner that I just wrote about the other day. I won't post any more pictures, just scroll down a little further to see that post!


For Parallel Programming, I've been working on a atomic orbital simulation, using OpenCL to evaluate the electron probability density function for a hydrogen atom at many, many points. It makes nice smooth images like this:

It's showing approximately a 20x speedup, moving from Zoe's CPU to GPU (Core i7 @ 2x2.66/3.33GHz to a NVIDIA GeForce 330M GT). The move from Zoe's CPU to Jayne's GPU (the 4890) is even more awesome; it's something like 40x faster!

Eventually (soon), I'm going to make an animation with it, and then it's time to write a paper!


For Advanced Computer Graphics, I've been working on a particle system simulator that uses (surprise!) OpenCL to simulate tons and tons of particles at once (millions, anyway). And render them, attractively (the renderer is still in its infancy). And it comes with a tool to design them, too (also incomplete).

I don't have any really interesting examples to show now, because I just got emitters to work. Below is a picture of something like 1,000,000 particles being blown away from the origin by two "simple"-type forces (they just push outward from a point, with inverse-square falloff).

And a video (which will only work if you're using a very recent Chrome or Safari, probably) of the same simulation, though with only 128K points. This simulation really isn't interesting because there's nothing complicated going on. I've got gravity working, which is a gazillion times more interesting and more complicated, but I'll post pictures and video of that some other day (it's also much, much slower).

It also turns out that the overhead of OpenCL isn't worth it for simple forces; it significantly speeds up complex (O(n^2)) forces like gravity (I'm aware of many ways to speed up n-body simulation, I just haven't had a chance to implement them yet), but for O(n) forces like below, it really only provides a tiny-to-near-zero gain.


All of this (plus normal coursework) leaves less time than desired for other things, but I still manage to occasionally put a few hours in to work on Sheeple. I feel bad that I don't have tons of time for RCOS work, though I will note that all of these projects are open source (all of them are under the 2-clause BSD license except Sheeple, which is GPLv3), so the general idea of promoting/using/writing OSS is still there :-)

I recently wrote and pushed a partial implementation of a Google Contacts backend for Sheeple. It's a lot smaller (and nicer, since it's written in Vala), and it's what I'd like to use for the time being while developing the UI and backend stuff, since it's a lot easier to change.

Another thing that contributes to slow Sheeple development is that everything now takes place in a VM; I don't have a native Linux install anymore, and I consider that a good thing. I've gotten sick of wasting time with a broken system, and I'm just not going to do that anymore - I don't care enough nor have enough time to spend to fix things, and I'm just generally all-around much happier in OS X. So both of my machines are running OS X, and I'm pretty sure that's how it's going to stay for the foreseeable future.

I should thank Moorthy and Sean O'Sullivan for putting up with me, and for constructing RCOS and keeping it alive. I wrote a long bit about what I think about RCOS and the people involved a few months ago, and that all still stands. Given this semester's overload (which will likely continue next semester) and how RCOS has worked out within this semester, I find it somewhat likely that I'm not going to participate next semester; I feel guilty about being paid to do much less work than I feel like I should be doing. I'll still hang around, certainly, and I'll (obviously) still write OSS, I'll even happily talk about stuff I'm working on, but the absence of that feeling of guilt/obligation/deadline (and also the ability to bounce between projects as I feel like it) will be quite the load off.