Beginning Game Programming, COMI 2040 Lab 6

Transcription

1 Beginning Game Programming, COMI 2040 Lab 6 Background This lab covers the second part of Chapter 3 of your text and the second half of lecture. Before attempting this lab, you should be familiar with the following concepts: Writing functions in Python. Invoking functions in Python. Passing data to functions. Returning data from functions. Assigning the return value of a function to a variable. If you are uncertain about any of the concepts just listed, you should review the second part of Chapter 3 before proceeding with this lab. Before proceeding with this lab, you should complete Lab 5. Overview Continuing with the enemies with hit points program, you will now group your long and difficult-to-read code into nice, neat functions. You will then invoke those functions. Learning objectives After this lab, you should be able to: Break a long program into functions. Pass data into and return data from functions. Use data that is returned from functions. 1. Enhance your program with functions If your program is anything like mine, you have a really long mess. Every single piece of this program will be easier to read if you break it up into functions. Model your program after this code, or work from mine:

2 """ enemies.py Maggie Burke 9/18/2010 A program that stores data about enemies. Now let's allow the user to fight the enemies until they're defeated. """ import random #low-life celebrity enemies enemies=["mel Gibson","50 Cent","Tom Cruise","Jenny McCarthy"] hitpoints=[25,20,15,5] maxattack=[5,5,5,3] weapons=["racist potty mouth", "moronic homophobic babble", "idiotic hyperactive babble", "disease"] # getcelebtoattack #You're going to move some code from below into here, look for the lines def getcelebtoattack(): print "Replace this line with code that does something." # attackceleb #Do some damage on a celebrity #The parameter "celebrity" contains the name #Returns final hit points for the celebrity def attackceleb(celebrity,maxhitpoints): #Calculate random damage from 1 to maxhitpoints damage=random.randint(1,maxhitpoints) #now let's find the enemy in the list loc=enemies.index(celebrity) #now inflict the damage, the hit points are at the same index in the hitpoints list

3 hitpoints[loc]=hitpoints[loc]-damage #set hitpoints to zero if it went below if hitpoints[loc]<0: hitpoints[loc]=0 #give the calling module back the final hit points for the celebrity return hitpoints[loc] # MAIN PROGRAM #attack until all are vanquished or you get bored... allvanquished=false userquit=false while (not allvanquished) and (not userquit): #pull out the code between these lines and put it into getcelebtoattack, #returning the name of the celebrity to be stored in the variable victim # #find out who your user wants to attack print "You can attack any of the following: " enemiesstring="" for enemy in enemies: enemiesstring=enemiesstring+" "+enemy print enemiesstring victim=raw_input("which ultra ugly celebrity do you want to expose? (Or 'Quit' to quit)> ") # #at this point, if you wrote your code correctly, victim should contain the name of the victim #or the word "Quit" if (victim=="quit"): userquit=true #Maybe right here you should do a check to see if "victim" is in your list, just in case #the user typed it wrong, and make sure you don't execute any code that would cause a crash, #maybe also print a little error message for your user???

4 if not userquit: #attack the celebrity: thehitpoints=attackceleb(victim,20) #print the result print "%s now has %d hit points." %(victim,thehitpoints) #right here is where you should call a function that does something fun, #gives the enemy a "turn" or whatnot. #Here's some code that does that, but it should really be in a function: attacker=random.choice(enemies) attackee=random.choice(enemies) #okay if a celebrity attacks him/her self, that's funny newhitpoints=attackceleb(attackee, maxattack[enemies.index(attacker)]) print "%s just attacked %s with %s!" %(attacker,attackee,weapons[enemies.index(attacker)]) print "%s now has %d hit points left." %(attackee, newhitpoints) #let the user see what's left print " " for index in range(len(enemies)): print "%s has %d hit points" %(enemies[index],hitpoints[index]) print " " #figure out if the user has won hitpointstogo=0 for hp in hitpoints: hitpointstogo=hitpointstogo+hp if hitpointstogo==0: allvanquished=true if allvanquished: print "Congratulations! You are celebrity blogger of the year and humanitarian extraordinaire!" elif userquit: print "Winners never quit and quitters never win. :-("

5 This might feel a bit long and intimidating! We've gone from very short programs to very long ones, but you built this up slowly (or something similar), so you should understand all of the pieces. The problem is, it's hard to read all of the pieces when they're together. It's much easier if you break out each piece that has a purpose that you can describe in one sentence into a function. This is an overview of the program if you look at it that way: 1. Define all of the lists that are our data 2. Define a function that gets (and returns) the name of the celebrity from the user that s/he wants to attack 3. Define a function that attacks a celebrity, given the celebrity's name and the max damage that can be done 4. Define a function that does something fun, like have a celebrity attack another celebrity 5. Main gaming loop, while the user hasn't won or quit: a. Get a celebrity to attack, using (2) b. If that wasn't a choice to Quit, then: i. Attack the celebrity, using (3) ii. Do something else fun, using (4) iii. Report the state of the game to the user iv. Calculate whether the user has won In the program above, I wrote one function for you. I put in a shell for a second function, and told you where to get the body of that function from. You'll have to figure out how to call it, how to return a value from it, and how to use that value. I suggested where you should write a third function (that would be (4) in the overview above), but didn't give you any other help. I also suggested that you put in a test to make sure the user has typed the name of the enemy correctly, so your program doesn't crash.