My school was rather inclined to disagree with my petition for a “prerequisite override permit,” which is what I need in order to register for the C++ class, ECE 3090. After all, you couldn’t possibly learn C++ if you hadn’t first implemented some discrete FIR filters in the digital signal processing course first.

OK, just read my response after my registration permit was denied:

Hi Xxxxxxx,

But I will lose interest in schoolwork and begin to find my course-load irrelevant and tedious. Soon I will feel as if I have lost my way, and either turn to religion and/or become a Management major. Either path will only further my anxiety about my capabilities and self-worth, and soon my very existence will come into question. I will wonder if school is worth my time, or if life is even worth living.

Years later, as I lay on a desolate sidewalk, a vagabond stranded by the School of Electrical & Computer Engineering, tears will stream down my face onto my primary religious text and/or my diploma for my Management degree. It will be my last of many cold, lonely nights on that sidewalk. Hunger and sickness have taken its their final toll on my frame, already thin and abused since the second semester of Georgia Tech.

But as the world fades to darkness, I will realize that my tears are not of sadness, but of joy, joy that I had completed my core subjects instead of junior electives.

Oh, the humanities!

But seriously though: could I talk to the professor teaching the class next semester about getting a prerequisite override permit? I really am quite confident about the material in the course, and would like to take it to boost my GPA, and because I feel it is more relevant to my major as well as my interests and skill level overall.

Thank you,
Xo Wang
gtID: XXXXXXXXX

On Tue, 06 Apr 2010 09:59:59 -0300, Xxxxxxx Xxxx wrote:

ECE does not override prerequisites for its courses. Once you have
successfully completed ECE 2025, 2030, and 2040, you can take ECE 3090.
ECE 3090 is offered every Fall and Spring terms, and occasionally in the
Summer. You will have plenty of time to take it in the future. Right
now you need to concentrate on completing your core subjects, not junior
electives.

Regards,

Xxxxxxx X. Xxxx
Manager, Undergraduate Academic Advising
School of Electrical & Computing Engineering
Georgia Institute of Technology
PHONE: 404-894-XXXX
FAX: 404-894-XXXX

Below is the result of your feedback form. It was submitted by xxx@gatech.edu (ZHAO WANG) on Monday, April 05, 2010 at 19:18:02.

grad_ugrad: Undergraduate
term: Fall
GTID: ———
course: ECE3090
major: CMPE
graduation_term: Spring
graduation_year: 2013

comments: I already have knowledge of C++ and programming in 3090; previously held a job at a game graphics/AI company doing software engineering with C++.

The response I got was essentially a straight-faced “no” and “go have yourself a terrible @#$%ing day” only without those specific words and phrased a lot less politely. Yes, less politely.

By the way, I’m not actually a Management major now. I’m just going to be an EECS who leans towards CS rather than EE. And hates life.

Simply put, ray tracing’s generating computer images through a physical simulation of light, by “shooting” rays from a viewpoint in 3D space and then “tracing” them along their paths for objects to draw on screen. Shoot a lot of them and you will have enough information for the screen.

This is far superior in quality and correctness, though also very much less efficient, than our current method of rasterization: gathering up all the objects we put into the virtual space, deciding what they should look like given a few arbitrary parameters, and then drawing them on the screen where we think they should go. Ray tracers produce such good-looking images, in fact, because they are accurate.

For an example, see Wikipedia’s exemplar specimen of ray traced work:

If you need more convincing, check out a small company in California called Pixar. I believe they make these moving pictures or something.

“Now Xo,” you ask, “why did you call this wonderful ‘tray racing’ technique the ‘dark side’ of computer graphics? Surely it would be the ‘light side (no pun intended)?’”

No, it’s not. I learned rasterization first, I worked hard at some very pointless but very fast software rasterizers, and I just like it more. Shoot me (no pun intended).

Anyways, I wrote a simple “classical” (properly known as Whitted) ray tracer for CS3451² as an assignment. To my surprise, it took only eight hours of marathon coding to write, none of them daytime. The work consisted primarily of making and fixing simple mistakes that, once I had worked out the math, were physically incorrect.

That was the nice bit of it all; if you had a rendering error, you can just look at your model of the world and see if you did something in a way that makes no sense in the real world. Once I fixed those mistakes, I had a pretty nice ray tracer, if trivial by today’s standards.

These are the technical issues I stumbled on (and have stumbled on before; I don’t learn too well from my mistakes³), and ones you probably should watch out for:

• Normalize your unit vectors!
  Rays have directions representing their straight line path through space. These are usually represented with unit vectors. If you don’t keep them normal, then the distances you get through ray-object intersections will be inaccurate. This will cause issues if you actually depend on distances at some point, like when you do shadowing or light attenuation.
• Check for negative intersections!
  When checking for ray-object intersections. Make sure you discard intersections that are behind the rays origin. Say that you parameterize your ray as o + td, where o is the ray’s origin, d is the direction (uuunit veeector!), and t is the scalar parameter indicating distance along the path given by o and d. If you get an intersection of t < 0, discard the intersection.
  
  Don’t do this:
  
• Terminate your reflection rays by contribution!
  When doing lots of bounces around shiny objects, that is, objects of constant of reflection K_refl > 0, make sure to stop doing more bounces when additional bounces will contribute no visible difference to the image. My measuring stick here is by recursive descent along reflection rays: with each bounce, I multiply the contribution factor (which starts out at 1) by the K_refl of the intersected object. If the contribution of the next recursive level is less than 0.5/255, which is half the value of least significance for an 8-bit/channel output buffer, then I consider further bounces to be useless and terminate further recursion. It’s just a performance thing.
• Don’t let your reflection rays check against its own origin!
  When bouncing reflection rays, be sure to not check for intersections against the object you just bounced it off of. It’s a simple way to avoid a rendering artifact known as surface acne⁴. However, this technique will prevent objects from casting self shadows, which are exactly what they sound like. Therefore, omit the reflection intersection check for the biggest thing in an object that does not self-shadow, e.g. spheres, triangles, planar polygons, etc. So if you are reflecting off an object composed of many triangles, don’t intersect the reflection ray against the triangle it bounced off of, but do check against the other triangles in the object.
• Intersect your shadow rays with geometry and lights!
  OK, this is hard to describe, but it’s important. You check for shadowing by shooting a shadow ray towards the light you’re trying to err, check for shadowing against, right? If there is an intersection with another object, then there’s something blocking the light, right? Non monsieur! What if the light is between the two objects? For a shadow to be cast, the distance to the intersection must be less than the distance to the light.
  
  Example: There is a light smack dab in between two spheres. It should look like this:
  
  
  Except when it doesn’t:
  
  
  Just for the heck of it, let’s add more magic:
  

So there you have it. Hopefully the technical bits in this post will help some poor uni student out there struggling to race his/her first tray, the writing has entertained you, and at the very least the pretty pictures got you all excited.

1. Not meaning computers will get fast enough to simulate light realistically in real time; meaning they will make dining trays big enough to fit young adventurous men like myself
2. Computer Graphics at Georgia Tech
3. Unless I write it down with lots of parentheticals and footnotes like this
4. See this article: It’s Really Not a Rendering Bug, You see…

I once had an English teacher at Stuyvesant who insisted with utmost sincerity that the character Kurtz of Conrad’s Heart of Darkness was so named because of its supposed phonetic similarity to “Christ.” Furthermore, Okonkwo of Achebe’s Things Fall Apart has his name originate from our subconscious understanding of long, “masculine” vowel sounds. How could a syllable be masculine?

Her most far-fetched comparisons, which she dispensed daily with an unconquerable, belittling sneer, were the only ones which could match in tenuity to this little headdesk I was subjected to in junior year: “The jolly baker down the street has elected to use powdered sugar instead of granulated sugar. What do you think the author intended by such a decision fraught with between-the-lines intention?”

NOTHING. The author intended nothing!

So when I decided to create a new avatar for myself, my traumatizing experiences with English class led to me write the following disclaimer: “I intended my work to be experienced as it has been created. I enjoy the way it looks, and this work has no further meaning beyond its initial appearance.”

Then I looked at my new piece of work, the Outline:

Yes, I did make it the way it is because it looks nice. But it very obviously contains additionally meaning, much of it inherited from its sire, the Stuyvesant Techtonics (Stuy Tech/Techtie) logo (the Tech):

I wanted to retain the nature of my work, the hexagonal power button symbol that represents the melding of electronics and mechanics that is robotics. I discarded the dramatic red bar, standing out starkly against the black and white, because that was what Techtonics was when I made the logo—a bold sliver of a team, surrounded by uncreative soulless career-seekers. But I do not need such an iconoclastic representation; I’m a pretty quiet guy. Besides, taking out the red just makes it work better for my website. I removed the sharp caps in the bar and the five-sixths hexagon as well. Techtonics was an intense, competitive team; I am a person.

Of course, this means that I will be finally phasing out the remnants of my previous logo, the Indoor:

which has made its presence known only in its favicon form , which is now replaced with . The new logo resized surprisingly well.

Previous iterations of the Indoor have looked like so:

That last one is from 2003 or 2004. I believe I stole it from another website, because I remember it as originally animated. Please forgive me, other website. I was young, and you have done me a great service for the original art that has served me for so long. However, scioly.org, which is where I first began to use it, had and still has a very strict requirement on avatar file sizes, due to hosting costs. I cut all but one frame from it and simplified the palette. I eventually shaped the frame to look like my own planes, and animated the image once more to arrive at the final product, but I still wonder how the original looked…

Also, I found this amusingly terrible GIF bunched with the collection that the Indoor came from:

Wow. The things I did at the age of 13.

Now, you might ask, why do I need a personal logo? I really don’t. I don’t have that much of an ego to want a pictograph that represents me. The real issue was that I was using my Techtonics logo everywhere; my Gravatar, my chat services, my computer login, etc. It was my only work of art that was at all notable. In fact, it was my only work of art that could be said to be a work of art.

However, I didn’t agree with the new Techtonics leadership after I left and they took the team over. I took issue with their interpretation of the principles of Techtonics (which is that there are none), as well as the low priorities they placed upon the various activities Techtonics traditionally participated in. I didn’t want to be using the same logo that represented people with whom I disagreed.

And that is how I know I am not an English teacher. My little picture actually represents real live people now.

Well, guess what. I got in somewhere else. I didn’t like it very much. And I got stabbed here.

Link: Georgia Tech student stabbed in Midtown
Link: GA Tech Student Stabbed Near Campus (they got my name wrong¹)

You see what happens when you get rejected from the school of your choice? This happens. I hate this fucking place.

I can’t believe I didn’t apply to Brown.

I’m leaving tomorrow.

1. No surprise there, but I actually do have quite a bit to say about FOX News’s skills at hunting me down

The image shown above is my entry for the first project in the Graphics course, which is to create a program that can represent points/edges in space in a 4×n (homogenous coordinates) matrix, and apply various transformations (rotate, scale, translate) to that matrix through matrix multiplication against a 4×4 transformation matrix. The list of edges should then be drawn to an image file or displayed onscreen.

The end result is that you can put a bunch of coordinates in and rotate them around to see how 3D they are.

Anyways, I don’t think I was supposed to use C++, Windows, gtkmm, or cairomm for my project, but then I doubt anyone will complain. After all, I believe that the output of it is probably better than the reference output in the project specs.

Project output:

Reference output: