• Your program will have at least two balls that bounce off the edges of the screen

  • They should properly reflect at the correct angle

  • They can phase through each other - don't worry about collisions
    
    

• Each ball should...

  • Start at a different location on the screen

  • Have a different xSpeed and ySpeed

  • Bounce correctly off the edges to account for with and height - your ball should not "phase" into the wall

When they hit the side of the screen

• • The first ball should change to a random warm color (red, orange, etc)

  • The second ball should change to a random cool color (blue, green, etc).

• Progression Advice

  • Draw a single stationary ball

  • Make the ball move

  • Make the ball bounce off the edge

  • Make sure it bounces right off the edge and doesn't push into any edges

  • Repeat with a second ball 

• Wait, but how do I make the ball bounce?

  • Read Coder's Handbook - Animation carefully.  If you want more help, look at Shiffman's bouncing ball example linked on that page.

• Is there a way to do this program without repeating so much code?

  • Yes - but it's beyond your powers right now.  We'll come back to this!

• I know it's not required, but ... how do I make the balls hit each other?

  • You'll need to see if one ball is inside of the other one.  You have their x positions and y positions, as well as their sizes.  If one ball is within another's radius....

You can do these extra credit options or come up with your own.  Note that your instructor won't help you solve these problems - they are meant to be additional challenges to do on your own!

Option 1 - Fancier Bounces

• • Have your ball grow when it bounces and shrink when it gets to be too big

  • Have your ball accelerate when it bounce and slow when it gets too fast

  • These are more complicated than they sound!  You'll have to think a bit about the ways bouncing works when the ball is outside of the bounds for more than one frame...
    
    

Option 2 - Collision

• • Have the two balls collide bounce off each other