This project illustrates how to do hit-detection with sprites using color. This lets you build a level using specific colors to cause events, without having to write new code each time. For our hit detection, we used four different colors for the sides of the ball. This allows us to detect hits on each side independently, so we can put in the right code to change direction. The color we use in our game world to detect hits is purple. Anywhere you put purple in this project will result in a wall that the ball bounces off of. You can make any shape object using purple, and it will work. One last trick: when you use colors to do hit detection, you probably don't actually want to see those colors while your game is running. To hide these colors, we switch costumes right before and after the hit detection runs. The switch happens so quickly that the screen does not have time to display it, even though the computer still has time to check it (the screen display refreshes much slower than the CPU cycles).
