Section 3Moving Your UFO on the Screen

Using Sprites for Game Graphics 31Variables Let You Control Your Game Over Time 34Loops Tell Phrogram to Do Something Over and Over Again 35Delay 38Encountering and Fixing Errors 39Exercises: UFOs and Cars and Planes! 42

Now that your UFO is on the screen at a specific location that you know how to control through the coordinate system, it's time to make it move around the screen. Before we move the UFO, though, let's go over how you do a couple of fundamental things with Phrogram, such as creating an entirely new program. First, click on the leftmost icon on the toolbar, shown here with a red box around it. This is the Create a new program tool:

When you click that icon, a new "tab" is added in Phrogram, ...

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