2. Pass the Ball

In this video, you will program the ball sprite to move when the spacebar is pressed.

First, click on the ball sprite. From the “motion” menu, drag out the “move 10 steps” block. Next, program the ball to *repeat* moving *until* it touches the edge of the stage. From the “control” menu, place a “repeat until” loop around the “move 10 steps” block.

In the “repeat until” block there’s a space to tell the blocks inside it when to stop repeating. In this case, the blocks should stop repeating when they sense that the ball sprite is touching the edge of the stage. From the "sensing" menu, drag out the “touching” block, and place it inside the “repeat until” block. Click the dropdown, and select “edge.” Click on the code to test it.

The ball sprite should move until it touches the edge of the screen, then stop. And it does. To make the sprite return to its starting location every time the code is run, you'll use a "go to x y" block. First, though, drag the sprite to its starting position. The values in the "go to x y block" will automatically update in the menu based on the sprite's position. Then, drag the "go to x y" block above the repeat loop. Click the code. The sprite moves until it touches the edge of the stage. Click the code again. It begins in its starting location, then moves until it touches the edge of the screen. Pretty neat!

To make this keep happening for the entire game, place a forever loop from the control menu around the code. Click on the code again. The ball sprite goes to its start location, then moves to the edge of the screen, then returns to its start location, over and over, and over again. Next, control when the ball sprite starts moving, so that it doesn't keep looping uncontrollably. First, click the stop sign.

To make the ball move only when it senses that the spacebar has been pressed, go to the control menu, choose an “if” block, and place it around the “repeat until” loop, under the “go to” block. Then, go to the sensing menu, and place a “key pressed” block inside the “if." Click the dropdown, and select spacebar.

Now, the code reads “forever, go to the starting location. If the spacebar is pressed, repeat moving until touching the edge. Once touching the edge, run the loop again, and return to the starting location.” Test the code by clicking on it, then pressing the spacebar. So far so good! Here's the game plan: Make the ball sprite move until it touches the edge of the screen using “move,” “repeat until,” and “touching edge” blocks. Give the ball sprite a starting location using the “go to” block. Make the ball sprite repeat these actions using a “forever” block. And finally, make the ball sprite move only if the user presses the spacebar with “if” and “key pressed” blocks.

In the next video, you will learn how to control the ball sprite’s direction.