Introduction to Computer Science with Scratch and App Inventor

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Now I have my winning condition set. How about a losing condition? I want my player to lose when their score is negative points (less than zero). I can set up the losing condition exactly the same way I set up the winning condition: 1) Create a new background that displays a losing message 2) Use an if block to check for a score that is less than zero 3) When the score is less than zero, display my losing background and broadcast the game over message. This is just one example of how a player can win or lose a game. Be creative and think of what works best for your game. For example: You could have the win condition be based on capturing a specific item, or completing a specific task. You could use two different variables: a points variable to track points and determine if the player wins and a health variable that decreases and is used to determine if a player loses (when their health variable is zero) Another option is to use a timer. Let’s say that I only want my player to win if they can score 10 points in less than 100 seconds. I can use Scratch’s built in time to check for this. The timer is located in the sensing blocks. To use the timer: 1) Click the checkbox next to timer to show the timer value on the stage 2) Choose when to start timing. I want to start my timer when the green flag is clicked (as soon as the game starts). Since I am handling winning and losing in the scripts for my stage, I will control the timer there as well. 3) Drag a reset timer block to where you want to start the timer mbrace Game Development Workbook Page 28
Click the checkbox next to timer to make it show up Add a reset timer block where you want to start the timer Timer will show up here on the stage. If you play the game now, you will see that the timer will count the seconds that the game is being played. Now we need to add a check based on the timer. We are updating our win conditions like this: The player WINS if: They score 10 points AND they have been playing for less than 100 seconds The player LOSES if: They have negative points OR they have been playing for more than 100 seconds AND and OR are called Boolean expressions in programming and are used a lot when we have more than one thing that we want to check. Use an AND when you have multiple conditions and ALL of them must be true o This is like the case for winning since it must be true that the user has 10 points and it must also be true that they have been playing for less than 100 seconds Use an OR when you have multiple conditions and only ONE of them must be true o This is like the case for losing since either the player must have a negative points value or they must have been playing for more than 100 seconds, but both do not have to be true. and and or blocks are available from the operators menu. Both have two slots for the conditions involved. mbrace Game Development Workbook Page 29
Page 1 and 2: Introduction to Computer Science wi
Page 3 and 4: LESSON 1: Getting Started with Scra
Page 5 and 6: I decided to pick a dinosaur. You c
Page 7 and 8: The direction that your sprite move
Page 9 and 10: Let’s add some yellow wait blocks
Page 11 and 12: Changing the Background on the Stag
Page 13 and 14: To use an if block to control the m
Page 15 and 16: Costumes and Animation Now that you
Page 17 and 18: Other useful blocks are the say and
Page 19 and 20: ? Now we know how to tell when the
Page 21 and 22: Here is one script that works. To m
Page 23 and 24: After you create a variable, you wi
Page 25 and 26: Winning, Losing, and Game Play Our
Page 27: You might have noticed that when th
Page 31 and 32: Scratch Review Now you have built y
Page 33 and 34: App Inventor Interface The App Inve
Page 35 and 36: The first thing that we will do is
Page 37 and 38: To add the mole to our program, we
Page 39 and 40: Your Blocks Editor Screen should lo
Page 41 and 42: We know that our X and Y locations
Page 43 and 44: Our mole shows up in the emulator,
Page 45 and 46: The last thing we need is the value
Page 47 and 48: Team Project Worksheet We have lear

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