92 lines
2.5 KiB
Markdown
92 lines
2.5 KiB
Markdown
# 2 player pong quiz answers
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a two-player game of Pong using TWO BBC micro:bits!.
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## Name
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## Directions
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Use this activity document to guide your work in the [2 player pong tutorial](/lessons/2-player-pong/tutorial)
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Answer the questions while completing the tutorial. Pay attention to the dialogues!
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## 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.
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<br/>
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```
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hasBall = false
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gameRunning = false
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```
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## 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.
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<br/>
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```
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claimBall = true
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```
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## 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.
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<br/>
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```
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input.onButtonPressed(Button.A, () => {
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if (claimBall) {
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pins.digitalWritePin("P0", 1)
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}
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})
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```
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## 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.
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<br/>
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```
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if (gameRunning) {
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if (paddleX != 0) {
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led.unplot(paddleX, 4)
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paddleX = paddleX - 1
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led.plot(paddleX, 4)
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}
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}
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```
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## 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").
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<br/>
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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.
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## 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".)
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<br/>
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```
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ballX = micro_bitTransfer.readByte()
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ballXVelocity = readVelocity()
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```
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## 7. Write the code that updates 'ball x velocity'. (Hint: look at the "update velocity" function.)
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<br/>
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```
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if (ballX == 0 || ballX == 4) {
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ballXVelocity = ballXVelocity * (-1)
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}
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```
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## 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.
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<br/>
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```
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led.unplot(ballX, 0)
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ballX = ballX + ballXVelocity
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ballY = ballY + ballYVelocity
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led.plot(ballX, ballY)
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```
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