If you are remotely interested in Actionscript, Flash, computer animation, games, or pretty stuff on computers – go get Kieth Peters’ book, “Foundation Actionscript 3.0 Animation: Making Things Move.”  Then check out
Keith Peters blog (but really his other sites).  After reading parts 1 and 2 of the book, which cover basic animation, I felt compelled to take one of the examples a bit further.

In Part 2: Basic Motion, the concepts of moving pixels programatically around the screen by shifting the x and y position every frame is introduced.  A ‘veloctiy’ is assigned to both the x and y values to determine how many pixels the object moves per frame.  The fountain example in the book demonstrates these concepts by shooting a bunch of colored balls from the bottom of the screen, with slightly random values for the x and y velocity.

I added some controls, just for fun.  Use the up and down arrow keys to increase or decrease the height, and use left/right to change the direction.  Also, if you look at the code, I changed the concept of x and y velocities to speed and angle. So rather then setting a velocity value for the x and y values of each ball, I set a speed and angle, and use this information to update the balls’ positions.  The original code remains in comments for reference.  Take a look.