Pac-Man's Ghost Behavior Algorithms 194
An anonymous reader writes "This article has a very interesting description of the algorithms behind the ghosts in Pac-Man. I had no idea about most of this information, but that's probably because it's difficult to study the ghosts when I die every 30 seconds. Quoting: 'The ghosts are always in one of three possible modes: Chase, Scatter, or Frightened. The "normal" mode with the ghosts pursuing Pac-Man is Chase, and this is the one that they spend most of their time in. While in Chase mode, all of the ghosts use Pac-Man's position as a factor in selecting their target tile, though it is more significant to some ghosts than others. In Scatter mode, each ghost has a fixed target tile, each of which is located just outside a different corner of the maze. This causes the four ghosts to disperse to the corners whenever they are in this mode. Frightened mode is unique because the ghosts do not have a specific target tile while in this mode. Instead, they pseudorandomly decide which turns to make at every intersection.'"
Always fascinating. (Score:3, Interesting)
I've known about this for years, but it's still quite fascinating. A 30-year-old game featured AI more sophisticated than what you'll find in most games today. Or at least AI appears more stupid and easier to foil today.
If I remember correctly Ms. Pac-Man added a randomization factor to avoid ghosts falling into set patterns.
Re:Programming lesson (Score:5, Interesting)
Interesting but from my memory (Score:4, Interesting)
Re:Programming lesson (Score:4, Interesting)
It's been scientifically proven that statistically men have better 3D perceptualization than women - yes some women are better at it than men, but when you plot it all out you get the regular bell curves, and men typically have higher preforming scores.
So it's not like jokes revolving around a woman's ability to park a car, or judging how far away an object is, or any of the things that seem to be related to navigation - they do have SOME foundation to it. (if you don't believe me, Google "Women's Depth Perception")
Much in the same way that colourblindness is strictly a male thing - if a woman is colourblind, it typically means that some dominant male gene actually took control when their eyes developed, which is quite rare in women. But also in Women its rare that they sometimes get a 4th "cone" in their eye that helps identifying in colours. This is why women tend to be better at items like interior design and Fashion, so the jokes about how "Men can't dress themselves" also have a good foundation. Like before, "some men are better than women at that sort of stuff" - but statistically speaking, this is a good strong point for women.
So - now that the science is out of the way - what does this have to do with Offensive jokes? That's the thing, they are just jokes. I mean in it in a light tone and while some might take it as derogatory, there are any number of things someone could make fun of me for (as you might have pointed out, my apparent lack of tact and manners!).
It boils down to this: do I value a good joke over someone elses potential feelings? Personally, I do enjoy a good joke. I think that the enjoyment it brings to me and others outweighs the possible negative feelings that a small contingent might actually feel - after all not ALL women are offended by such jokes.
A wise man once said... well I can't remember the exact words, but it was something along the lines of "Wisdom starts with humility". If you can't laugh at yourself than thats something you should work on. Recognising your shortfalls is the first step to overcoming them.
Now - the biggest problem I have with people is when they can't seperate Discrimination, prejudice, or harassment from humour. Like when you're at an Open source conference, and you're a women, like the article you linked. Guys taking upskirt photos of women? Yeah sexual harassment. Ignoring females because they are believed to be non-technical? Yeah discrimination. A picture of a girl in a Bikini during a slide show to say "That was just to get your attention" - Thats humour! It's meant in light fun, I bet if you had enough girls around you'd find them chuckling at the idea as well.
Point is - people need to lighten up. If more people could understand the difference between humour and harassment - the world would be a much better, and funnier place.
Re:Programming lesson (Score:5, Interesting)
Take note CS professors: writing a Pac Man ghost algorithm would be an awesome exercise.
I wrote a PacMan in GWBasic when I was around 13 or so.
The Ghost algorithm was one of the more interesting problems. The chase rules were simple... at each intersection the ghost chose to move towards pac-man, with the one caveat that it wasn't allowed to simply reverse direction. There was also a smallish random chance that the ghost would go a different direction if available.
This made them mostly but not entirely predictable, and also helped break them up when multiple ghosts ended up in the same place behind pac-man. And was the only way they used the left-right 'teleporter'
It worked well enough and by fine tuning the random chance of going in a random direction I was able to get a pretty satisfactory game.
The algorithm was actually based more on my observations of lode-runner than of PacMan. (I desperately wanted to be able to write a lode-runner type game, but I was self-taught... and didnt' under stand data modelling. My pacman sprites navigated the maze by acutually looking a the pixel colors around them... white was a wall.
My next project was tetris a couple years later, in pascal, with the same sort of inspect the pixels to see if a row was complete, and to stop falling, see if rotations were allowed, etc.
I remember having the data model epipaphany when I was trying to write a variable width font word processing thing (again in basic), and I couldn't for the life of me figure out how to support 'backspace'; looking backwards at the screen and comparing the pixels with the bitmaps for the different letters was simply a mess...hmmm... instead of simply drawing the letters as I type and moving the cursor forwards what if I put the letters I typed into a string as well... ooooooooooh.
A real personal Eureka moment there.
Re:Programming lesson (Score:4, Interesting)
It's been scientifically proven that statistically men have better 3D perceptualization than women - yes some women are better at it than men, but when you plot it all out you get the regular bell curves, and men typically have higher preforming scores.
Really now? Can you link me to a few unbiased studies the topic with statistically significant sample sizes and shows results of men having, not only higher scores, but statistically significantly higher scores? I assume, of course, that you also have available the justification for why we can trust the tests to be testing purely for 3d perceptualisation, without testing for additional unrelated factors (such as how well you can decipher difficult instructions, a common additional factor in such tests). And I also trust that these studies have properly isolated for sex, ensuring that additional factors such as training and practice in related skills or a lifetime of "you can do anything" vs. "oh, you're just a girl" have no bearing on the final results?
I'll be rather impressed if you can show me any such study. Now, I'll be the first to admit that not all people are created equal and that it is quite possible that people of different sexes and genders and races and sexual orientations have some amount of differences. However, I think you'll find that most of these studies in these topics are entirely inconclusive after you consider all of the factors surrounding them.
It's also worth noting the striking parallels to the number of 19th century studies "proving" that black people were strictly inferior to white people. Confirmation bias can prove anything, as it turns out.