Pi Graphic

I wrote the following program as a predecessor to another program I wanted to write. It's just a computer-generated graphical image, so it is not user-interactive. I included the code in this post, in case you're interested in seeing how I did it.

Also notice that each time you reload the page, the image is slightly different. This is because I set it up to generate certain aspects randomly.

Fire! Fire!

On Khan Academy a few days ago, a user asked for help. He said I was known for my animations, and that he needed fire for a game. A couple of days later, I tried writing a fire system. A couple of hours after that, I was done.

The result: a program that many people enjoyed. In only 20 hours, 46 users had voted it up. It has been 4 days since I wrote the program, and it now has at least 97 up-votes.

To create the fire, I used a particle system of a lot of transparent ellipses, a good bit of math, and Perlin noise. I added the wind yesterday, using Perlin noise to make transitions smoother. The program doesn't interact with the user; it's only supposed to look cool.

Live Chat

I recently discovered a really great website: firebase.com. It will store data for your applications, enabling you to write really awesome programs (such as multi-player games) using it - and the Development account (which I used) is free!

To communicate with the API, I had to learn HTML. I also learned some CSS and jQuery to make things easier. Then I wrote a live chat app using my knowledge.

In the app, you can use HTML to format your comments. At one point I allowed use of the &ltscript&gt tag, but after users abused it I disabled it. I also added a couple of new tags: &ltconsole&gt and &ltincode&gt You can post a comment by either clicking "Post Comment" or pressing the Alt key on your keyboard.

Fix Your Window

Click to try out the program!

In my original Smash It! program, I had a message that said, "Want me to fix it? Ask in Tips & Feedback!" I didn't want it to automatically fix itself, because that wouldn't be true to life. When you break a window, you live with the consequences.

Well, a lot of users wanted me to fix the window. One of the users figured out how to fix it himself, and started telling everybody how to do it. I didn't like that; it totally ruined the point of my program. Fixing a window shouldn't be easy. So I modified my code, and his solution was outdated.

He found a new method for fixing the windows. At first he didn't want to tell me about it, for fear I would circumvent, but finally he decided I wouldn't be able to. Laughing with pleasure, he wrote a fix-it program that used the method to fix windows, and started telling everybody about it.

I didn't like that. So I came up with a way to make his program stop working. I set things up using HTML5 storage so that his program worked great... for him, at least. For everybody else, it was useless. He didn't think of fixing it, because whenever he tested it, it worked. In fact, he happily talked about how good he was at programming. I just played along; ignorance is bliss.

I told him about it the next day. It's no fun to fool someone if they never know they were fooled.

Anyway, other users were writing fix-it programs, too. I decided it was time for me to write a decent one - a fix-it program that was guarantied to work. I didn't want it to ruin the point of my original program, so I created some virtual money; you could pay 30 virtual dollars to fix the window. My program made it to the top of the hot list; it was as popular as the original program.

Smash It!

Click to start

This was a very popular program I wrote. It makes use of HTML5 storage to remember whether the window is broken. Try clicking on things, and see what happens!

Streaks Special Effect

Click to start

Here's a program I wrote recently. It converts an image into an image with streaks. It is not an interactive program; you can only watch it.

Sparking Ball

Here's a program I wrote about a week ago, for the graphics. It isn't a game, and it isn't a tool; it just looks cool. At least, I hope it does.

UPDATE: I modified the program so you can click for another ball.

If a little green guy pops up and complains about something, click restart.

Art Maker

Here's a very successful program I wrote recently. You just scribble on the screen, and press Enter; the program will generate some code for a program. You just copy the code, and then use the code as a new program on Khan Academy.

If you make a mistake, press Z to undo. As always, if you have a problem, comment and let me know!