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December 20, 2008
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December 5, 2008
Indoctrination: doing it right.
GeneralI stumbled about two interesting articles concerning education in Europe this week. In Spain the socialist party introduced a new course called ‘Education for Citizenship’ which covers topics like the Spanish constitution, how the spanish society works etc.
In Rumania (fittingly straight on the other side of Europe), the Theory of Evolution is not taught anymore in schools.
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November 22, 2008
Computation
ScienceWhat is computation? If you look into the online edition of the Merriam-Webster dictionary you will find that it is a synonym for calculation. And then apparently things get very tough to define, because clicking on calculation tells us that it is “the process or an act of calculating”, calculating being “making calculations”. This circular reasoning has a certain religious argument aftertaste to it. Still, we can all agree that computation (as so many other things) is like porn: it may be hard (SNORT) to define, but we know it when we see it.
But definitely, if you want to be able to have some theoretical results for computer science you need to have a clear definition. Sure you can do a lot going simply by the gut feeling, but we know from the history of mathematics that natural definitions can lead to problems (see the Russel’s paradox). In the need of formal definition a trick much used (or at least that is my feeling) in math is, instead of giving a clear definition (however you would manage to do that) for something and then creating a model for it, they create a model and define the meaning of the concept through it. There is more than one model our days, but the most common is the so-called Turing Machine. Problems are computable if one can write a program for a Turing Machine that solves the problem for any instance (or tells you there is no solution). No known models are more powerful than the Turing Machine (apparently not even quantum computers). Powerful is here used in the sense of being able to solve a problem algorithmically with it. Maybe another day I’ll write about Complexity Theory, i. e. if we can solve a problem and, if the answer is ‘yes’, how difficult it is to do so.
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November 14, 2008
Who’s your expert?
Chomsky is my beer-buddy, GeneralTV experts are a plague. Really, this has gotten out of hand! For every damn tidbit of “fact” an “expert” needs to be “interviewed”! But the worst part is: over the whole polemic bawling the real expertise simply drowns. Observe:
This is just fun. Mr. Schiff is probably laughing his ass off right now. Aside from that, what really cracks me up is the appearance of Ben Stein — the guy that landed and epic fail with his wanna-be documentary about “Intelligent Design”.
Hopefully that teaches news programs something… ah, just kidding. They’ll never learn.
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November 12, 2008
Vector geometry, part one.
TutorialIn the following weeks I plan on writing several articles about collision detection in 2d games, especially for flash. But before that I have to create some common ground which I intend to do with the following posts.
The topic at hand is basic geometry and how to express it usefully in programs. Starting at the most basic element, a point is a tuple of two coordinates (x, y) or (x1, x2) . Points are pretty useless in games, especially since vectors can be misused to ‘emulate’ them. Mathematical a vector is an element of a vector space which satisfies a number of properties (which are interesting, but not really useful in this context).
The fun thing: vectors in 2d euclidean geometry (which I’ll call simply vectors from now on) look exactly like points; they too contain two coordinates (x1, x2). The difference lies in the geometric interpretation and the operations attached to it: a vector is seen as an arrow that points into the direction indicated by the coordinates. Just imagine an arrow drawn from the origin (0,0) up to the point (x1, x2). This arrow is what we all a vector. Note that the vector itself is not “fixed in space”, it describes a direction, not a position.
In contrast to points we can add, subtract and even multiply these arrows — and all those operations have a simple, geometric meaning. I’ve prepared some simple .swfs that contain the important formulas as well as a graphical demonstration of how the operation can be interpreted (try dragging the arrow’s pointy ends around).
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November 3, 2008
Stop using hitTest()
Tutorial
Every now and then I go over to the Kirupa forum and look around for interesting topics on actionscript game programming (with Flash, I’m not really into Flex). About every tenth post in the game programming area deals with some kind of collision detection or collision response problem. About 99% of those posts can be answered very simple: stop using hitTest().
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November 2, 2008
On Zobrist hashing
Code, TutorialAttending the annual competition on board game AIs, I stumbled across a few nice ideas from that area. I especially find the idea of zobrist hashing to be very attractive. This hashing technique was invented, as the name probably suggests, by Albrecht Zobrist1. Zobrist also wrote the first computer program that was able to endure a whole game of Go.
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October 31, 2008
Happy Halloween
ParanoiaWell, it is halloween again. One of these “holidays” that people use as a rather sad excuse to dress up and show everyone how unassured they are about their gender. Although an oversea import, this custom gets shoved down our throats every year and forcefed to society in the name of ye glorious cultural exchange.
But I guess nowadays it is considered cooler to crave inspiration by other cultures than to celebrate one’s own. When I was ten, I don’t remember anyone around here celebrating halloween at all. Then again, I was probably too drunk to notice.
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October 26, 2008
I am using a recursive algorithm
Chomsky is my beer-buddy, GeneralThere are certain painful moments in the life of computer scientist when confronted with the pop culture stereotype reflection one is given through the uncountable channels of the modern media landscape. Cruel fate wants it that frequent encounters with our distorted images happen during the intimate ritual Slacking Off With Our Favorite Show.
Imagine: the mood is set; a cold beer and a still virgin bag of chips are comfortable positioned at arm’s length, the light is dimmed and real life is veiled by a hermetic barrier of venetian blinds and inch-thick dirt on the windows. The first well-known chimes of the theme music send a pleasant shiver of anticipation through your body and by the end of the intro you are completely drawn into the consoling alternate reality expected to last exactly 45 minutes — enough time for the plot to unfold, suspend and finally resolve; leaving you with a satisfactory feeling of having accomplished something (by proxy).Nothing can ruin this ritual more than being reminded that this is all just a story, something made up by other people, something artificial (because then you immediately realize that so are your positive feelings, mere empathy for the heroes you identify with; which where created to be identified with by people like you).
And nothing does the job better than hearing your heroes say something utterly stupid. Something like
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