Scientific computing: Sharing is caring

You're currently sitting in front of a high-tech, superpowered computational machine. It's capable of running calculations in a second that would take the human brain hours or even days. What are you using it for? Sure, you write code and play high-end games, but do you really do that all the time? Chances are there are days where all you do is check email, stare blankly at Facebook, and browse /r/cats before getting up to make yourself lunch, leaving your browser open to a picture of a stranger's cat.

The best use of time

Doesn't that feel like a waste? It's like what Google employees complain about: your computer is capable of much more than you're actually telling it to do. It's overqualified for its cat-picture-displaying job. Wouldn't you rather use your laptop to its fullest extent? And maybe help science?

There are tons of projects where you can donate your unused CPU power to help scientists run demanding computations for their research. This is the basis of distributed computing, where computational power is divided between a network of computers; this gives the power of a supercomputer without the monetary or space requirements. Distributed systems are especially useful for scientific computing (also known as computational science), which is centered around constructing mathematical models of scientific problems. Scientific problems that could use your help.

Pictured: helping

So now I've convinced you. You're all set to donate some spare PC power to a worthy scientific cause. Where do you get started? Well, for starters, Wikipedia has a whole list of distributed computing projects, which should give you enough of a jumping-off point. For those of you too lazy to change pages, here are some cool ones:

Electric sheep: alright, this isn't exactly science. But it's pretty cool anyway. While your computer sleeps, it talks to other computers on the Electric Sheep network. Together, your computers share the work of creating complex crazy abstract shapes and fractals.

Cosmology@home: if you want a loftier goal with your computing, the people at Cosmology@home is working to find the model that best fits the Universe. You know. No big deal.

Einstein@home: keeping with the space theme, Einstein@home uses your computer's idle time to find neutron stars -- they've already found over three dozen and are supported by the American Physical Society.

Computer graphics: Cast your rays

I'd be willing to bet money that you've played (or at least seen) some sort of generic dungeon-crawler game with high walls, repetitive textures, and a very basic 3D engine.

Looking at you, Dungeon Master

These games tend to end up with a cult following, but people generally aren't too impressed with the game itself; in a world where true 3D immersion is just baby steps away, blocky pseudo-3D dungeons aren't that cool. Not anymore, anyway. Go back about twenty years, though, and this was pretty high-level stuff. 

Remember the Wolfenstein games? You, the blocky hero, have to sneak through and out of a castle (or bunker), shoot Nazis, and save the day. The first two games, Castle Wolfenstein and Beyond Castle Wolfenstein, looked like this: 

I wasn't kidding when I said you were blocky

Then suddenly, in 1991, Wolfenstein 3D (the grandfather of 3D shooters) came out looking like this: 

Such depth!

It feels a whole lot like 3D (albeit unrealistic 3D), but it still ran on a 2D platform. All semblance of 3D in Wolfenstein 3D was faked using a technique called ray casting. Ray casting divides the map into a grid. Each entry on the grid can either be "wall" or "not wall." Then, for every vertical line in the player's field of vision, a ray is sent from the player out through that line until it hits a wall. 

Rays extend from the player (the green dot) to the wall (the blue squares)

The distance from the player to that wall is calculated, determining the displayed height of the wall (far-away things look little, etc.). This principle also applies to enemies -- the longer the ray from you to Herr Nazi, the smaller his sprite is scaled. There are a ton of subtleties to this (how do you determine how often to check for a ray-wall intersection? what about field of vision?) and lodev has a very detailed and clearly-written introduction to ray casting page here that can clear up some uncertainty (that's also where I got my grid image). 

With ray casting, faking 3D on a 2D platform became easy: the implementation is straightforward and the calculations were so easy that real-time ray casting could be done on a 286. Unfortunately, giantbomb.com is a buzzkill and pointed out all the things you can't do with ray casting: 

• Walls can be of only one height
• All cells are of the same width and height
• Walls must be one color per face
• The camera is unable to rotate on the x-axis (look up or down)
• There can be no cells above cells (e.g. the first and second floor of a building)
• Walls must be either perfectly horizontal or perfectly vertical

Those dungeon games are making sense now, right? Walls of one height? Check. One color? Grey goes with everything. Can't look up or down? Don't need to in a dungeon; it'll just be ceiling and floor. Perfectly vertical walls? No reason to make your dungeon fancier than that. 

If you're thinking of making a simple game, dungeon crawler or otherwise, ray casting is a good technique to know. It's a simple implementation, so you can spend more time thinking about a plot that doesn't suck. You can use the info at lodev to get started, or there are video tutorials from Unity3DStudent and Ravi Ramamoorthi (check that one out just for his voice).

Or if you're really lazy, I think The Raycasting Game Maker does most of the work for you.