WEEK 5
VARIABLES & GAME SYSTEMS
VARIABLESTHAT REMEMBERNUMBERS
SCORESYSTEMS
LIVESANDHEALTH
TIMERSTHAT COUNTDOWN
MAKING GAMES FEEL REAL!
HOW DOES A GAME REMEMBER YOUR SCORE?
HOW DOESMARIO KNOWYOUR COINS?
HOW DOESMINECRAFTKNOW YOURHEALTH?
HOW DOES ATIMER KNOWWHEN TIMEIS UP?
ANSWER: VARIABLES!
A VARIABLE IS A BOX THAT HOLDS A VALUE
LIKE ASCOREBOARDTHAT UPDATES
LIKE ABACKPACKTHAT COUNTSYOUR ITEMS
LIKE ASTOPWATCHTHAT TRACKSTIME
VARIABLES CAN HOLD NUMBERS OR WORDS!
STEP-BY-STEP IN SCRATCH
1. CLICKVARIABLESCATEGORY(ORANGE)
2. CLICKMAKE AVARIABLE
3. NAME ITSOMETHINGCLEAR LIKE"SCORE"
4. CHOOSEFOR ALLSPRITES
THE TWO MOST IMPORTANT VARIABLE BLOCKS
SET [SCORE]TO (0)REPLACESTHE VALUECOMPLETELY
CHANGE [SCORE]BY (1)ADDS TOTHE CURRENTVALUE
SET = START FRESH • CHANGE = ADD OR SUBTRACT
WATCH ME CODE A SIMPLE SCORE
WHEN GREENFLAG CLICKED
SET [SCORE] TO (0)
FOREVER
IF <TOUCHING [FRUIT]?> THEN
CHANGE [SCORE] BY (1)
NOTICE: WE SET TO 0 FIRST, THEN CHANGE BY 1!
ALWAYS SET YOUR VARIABLES AT THE START!
WITHOUTSET TO 0:SCORE KEEPSGOING UPEVERY TIMEYOU RESTART!
WITHSET TO 0:SCORE RESETSFRESH EACHGAME!
RULE: ALWAYS SET VARIABLES WHEN GREEN FLAG IS CLICKED
WHO CAN SEE YOUR VARIABLE?
FOR ALLSPRITES:EVERYONECAN READAND CHANGE ITUSE FOR:SCORE, LIVES,TIMER
FOR THISSPRITE ONLY:ONLY ONESPRITE CANUSE ITUSE FOR:SPEED, MYHEALTH
LET'S BUILD A GAME TOGETHER!
CATCHFALLINGFRUIT
EARNPOINTSFOR EACHCATCH
LOSEA LIFEIF YOUMISS
BEAT THETIMER!
FOLLOW ALONG STEP-BY-STEP!
MAKE THESE THREE VARIABLES (FOR ALL SPRITES)
SCORETRACKSPOINTS
LIVESTRACKSCHANCESLEFT
TIMERTRACKSSECONDSLEFT
CHECK THE BOXES SO THEY SHOW ON THE STAGE!
ON THE BOWL/BASKET SPRITE
SET [LIVES] TO (3)
SET [TIMER] TO (30)
GO TO X: (0) Y: (-150)
START FRESH EVERY GAME!
ARROW KEY CONTROLS
IF <KEY [LEFT ARROW] PRESSED?> THEN
CHANGE X BY (-10)
IF <KEY [RIGHT ARROW] PRESSED?> THEN
CHANGE X BY (10)
ON THE FRUIT SPRITE
GO TO X: (PICK RANDOM-200 TO 200) Y: (180)
SHOW
REPEAT (60)
CHANGE Y BY (-5)
STILL ON THE FRUIT SPRITE
IF <TOUCHING [BASKET]?> THEN
PLAY SOUND [POP]
HIDE
CATCH FRUIT = SCORE GOES UP BY 1!
WHAT HAPPENS WHEN FRUIT HITS THE GROUND?
IF <(Y POSITION) < [-170]> THEN
CHANGE [LIVES] BY (-1)
PLAY SOUND [BUZZ]
CHANGE BY (-1) MEANS SUBTRACT! LIVES GO DOWN!
CHANGE BY (-1) = SUBTRACT 1
CHANGE BY (1)ADDS 1SCORE: 5 → 6
CHANGE BY (-1)SUBTRACTS 1LIVES: 3 → 2
CHANGE BY (5)ADDS 5SCORE: 10 → 15
THE MINUS SIGN MAKES THE NUMBER GO DOWN!
ON THE BASKET SPRITE (A SEPARATE SCRIPT)
REPEAT (30)
WAIT (1) SECONDS
CHANGE [TIMER] BY (-1)
COUNTS DOWN FROM 30 TO 0 — ONE SECOND AT A TIME!
TWO WAYS THE GAME CAN END
OUT OF LIVES
IF <(LIVES) = [0]> THEN
SAY [GAME OVER!]FOR (2) SECONDS
STOP [ALL]
TIME'S UP
IF <(TIMER) = [0]> THEN
SAY [TIME'S UP!]FOR (2) SECONDS
TRY THESE THINGS
DOES SCORESTART AT 0?
DO LIVESSTART AT 3?
DOES SCOREGO UP WHENYOU CATCHFRUIT?
DO LIVES GODOWN WHENFRUITHITS GROUND?
IF SOMETHING IS WRONG, USE THE 3-STEP DEBUG METHOD!
LEVEL 1ADD SOUNDEFFECTS FORCATCH ANDMISS
LEVEL 2DIFFERENTFRUIT GIVEDIFFERENTPOINTS
LEVEL 3ADD AHIGH SCORETHAT SAVESBETWEEN GAMES
CHOOSE YOUR CHALLENGE LEVEL!
VARIABLE NOT WORKING? CHECK THESE:
DID YOUSET IT TO0 AT THESTART?
ARE YOUUSING SETWHEN YOUMEAN CHANGE?
IS THEVARIABLECHECKED TOSHOW ONSTAGE?
IS THECODE ONTHE RIGHTSPRITE?
YOU CAN NOW:
CREATE ANDUSEVARIABLES
BUILDSCORE ANDLIVESSYSTEMS
MAKECOUNTDOWNTIMERS
USENEGATIVENUMBERS TOSUBTRACT
YOUR GAMES FEEL REAL NOW!
WEEK 6: "LEVEL UP"
CHOOSEYOUR OWNPATH
CLONEMASTERS
CAPSTONEPLANNING
GET READY TO PICK YOUR ADVENTURE!
GIVE YOUR PROJECT A GREAT NAME
"FRUITCATCHERWITH LIVES"
"SCOREKEEPERGAME"
"UNTITLED"NOPE!
SEE YOU NEXT WEEK, CODERS!
