# 2 player pong quiz answers a two-player game of Pong using TWO @boardname@s!. ## Name ## Directions Use this activity document to guide your work in the [2 player pong tutorial](/lessons/2-player-pong/tutorial) Answer the questions while completing the tutorial. Pay attention to the dialogues! ## 1. Write the two global variables that record if the player has the ball and if the game is running, and assign these variables to their initial values. <br/> ``` hasBall = false gameRunning = false ``` ## 2. Write the global variable that keeps track of the game state in which whoever presses button A first will get to start the ball. Assign this variable to its initial value. <br/> ``` claimBall = true ``` ## 3. Write the code that creates a condition to know when Button A is pressed. Then write the 'If statement' to ensure that 'claim ball' is true. If the claim ball is true, then write the code that sets P0 to 1 to signal to the other device that the player has claimed the ball. <br/> ``` input.onButtonPressed(Button.A, () => { if (claimBall) { pins.digitalWritePin("P0", 1) } }) ``` ## 4. Write the code to move the paddle right when button B is pressed. Be sure to check if the game is running and if the paddle is not already on the rightmost edge. <br/> ``` if (gameRunning) { if (paddleX != 0) { led.unplot(paddleX, 4) paddleX = paddleX - 1 led.plot(paddleX, 4) } } ``` ## 5. What are the three pieces of information that we send to the other device when transferring the ball? (Hint: look in your "transfer ball" function, and look for any places that contain "transfer byte"). <br/> The device first transfers a bit of 1 to indicate that the device is going to transfer the data of the ball. After that, the device transfers the x-coordinate of the ball, and then the x-velocity of the ball. ## 6. Using the function "read velocity", write the code that reads the x-coordinate and the x-velocity of the ball. (Hint: look at the function "read ball".) <br/> ``` ballX = micro_bitTransfer.readByte() ballXVelocity = readVelocity() ``` ## 7. Write the code that updates 'ball x velocity'. (Hint: look at the "update velocity" function.) <br/> ``` if (ballX == 0 || ballX == 4) { ballXVelocity = ballXVelocity * (-1) } ``` ## 8. Write the code to move the ball. To move the ball, unplot the ball's original position, update its position variables, and then plot the ball's new position. <br/> ``` led.unplot(ballX, 0) ballX = ballX + ballXVelocity ballY = ballY + ballYVelocity led.plot(ballX, ballY) ```