Monthly Archives: May 2010

Insane: Arcattack: Faraday Fun- Imperial March

I once read about a demonstration given by Walter Lewin at MIT where he backs his head up against a wall, pulls a heavy weight on a pendulum up against his chin and lets it go. He then holds his head in the same position as the weight swings away and then back, coming to within an inch of his chin, because he trusts that the laws of physic are real and accurate (it’s toward the end of the video). I think this video one-ups him…


A blast from my programming past

Years ago I programmed regularly in Revolution. I hardly do anymore, but I’m still subscribed to the mailing list and every once in a while someone posts something that I used to be pretty decent at, so I dive back in. This is an example of that. 

An anonymous poster is trying to replicate Galaga in Revolution. Graphic video games like that aren’t really Rev’s strength, and the poster immediately ran into speed problems. Rev just doesn’t have the ability to directly update the locations of multiple objects repeatedly in a way that makes sense for video games. In short, it’s no Flash killer.

That said, there are things you can do to get things done anyway. In particular, the move to points command is your friend. You can use 

   put the width of this stack into w
   put random(w) into x

   repeat with y = –25 to the height of this stack + 25 step 10
      put abs(x + 20 * random(2) – 30) into x
      if x > w then put 2 * w – x into x
      put x,y & cr after p
   end repeat

   move image “enemy” to pointsList in 5 seconds without waiting

and if you have set up the points in pointsList appropriately, you’re set for five seconds. Further, image “enemy” will receive a moveStopped message when it finishes, allowing you to start the process over again. In this version of Galaga, enemies start above screen and go off the bottom, so this works perfectly.

One drawback of this is that they can’t (easily) go off the left side and come in on the right, or vice versa. Off the top of my head the easiest way to do that would be to check as you go along and if the ship ever goes off the side, stop there, calculate how long the move should take, and then write code to pick up from the opposite side when the moveStopped message arrives.

The same sort of thing is even easier for the bullets:

   repeat with i = 1 to 12
      if i > 11 or item 2 of the loc of grc (“fire” & i) < 0 then exit repeat
   end repeat
   if i = 6 then exit rawkeydown
   set the loc of grc (“fire” & i) to the loc of image “ship”
   move grc (“fire” & i) relative (0,(- the height of this stack)) in 2 seconds without waiting

I could have kept track of which bullets were available but I took the easy way and just checked to see if they were off the top of the screen.

Performance. The original code had a hard time moving one enemy and a few bullets. This version handles three enemies and 11 bullets smoothly (on my computer). I’m still simply moving the player’s ship; I’d fix that if I were going to spend any more time on this. If you have Revolution, feel free to download this and poke around.

Impossible motion: magnet-like slopes « Best Illusion of the Year Contest

Do yourself a favor and press play before you get a good look at the preview:

This is a really nice illusion, created by nothing more than creative use of perspective. It was created by Koukichi Sugihara Meiji at the Institute for Advanced Study of Mathematical Sciences, Japan. The motion of the balls just insanely sells the illusion.

I sound like a broken record

St. Louis is a non-stop amazement. Katerina and I decided to walk to Crepes Etc. tonight. It’s a beautiful night for walking, and it’s less than a mile away.

As we’re walking along Waterman we hear music and see a light. It’s hard to make out in this photo but that’s a huge screen TV. In a school park. Playing “Up.” With free kettlekorn. Everyone in the neighborhood is there. We told them we were set on going to get crepes and they offered us kettlekorn to go.

I love this town.


Tablets that are (not) going to Rule the Coming Years | TechHotshot


“Sometime back laptops made the world wire-free and mobile. One could work from anywhere; but laptop today is no longer a substance of surprise. The glamour quotient has shifted towards a new cool stream of gadgets called Tablet PCs.”

“Today we are at the altar where tablets are empowering to become the gadgets of tomorrow and witnessing the growth potential of tablet industry it would not be wrong to say that 2009 was a year of laptops and 2010 will be a year of tablets.”


This is fundamentally flawed reasoning. The author is assuming that ten years after Bill Gates first proclaimed that the laptop and desktop would be supplanted by the tablet, now just happens to be the time people are ready to make the switch. That’s no more true than the idea that one hundred years ago people decided they’d had enough of horses and it was time to adopt another mode of travel.

People are buying the iPad because the iPad works as a tablet, not because they’ve finally decided they’ve had enough of laptops. The PC industry has a ten-year history of producing tablets that few people want. There is no reason to think that just because Apple has produced the iPad, people will start snapping up the Dell Streak or the Samsung Q1.

If other manufacturers manage to copy the iPad really well, or produce something useful themselves, they have a shot. Otherwise the next ten years of tablets will be like the last ten years, only thinner and lighter and more desperate as the iPad’s market share grows.