GETTING STARTED WITH PYGAME ON THE RASPBERRY PI

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1 GETTING STARTED WITH PYGAME ON THE RASPBERRY PI Worksheet And Cheat Sheet.technoisaledcation.co.k This resorce is copyright TechnoVisal Limited 2017 bt permission is gien to freely copy for edcational prposes.

2 1. SETTING UP YOUR GAME LOOP First open the Python 3 editor (IDLE) and make a ne python fle. Add import instrctions to yor fle to load in the pygame and sys modles. Import the locals from pygame. import pygame, sys from pygame.locals import * Initialise the pygame modle and create a ne pygame indo, setting the display mode of the indo. Then gie it a caption. pygame.init() DISPLAYSURF = pygame.display.set_mode((400, 300)) pygame.display.set_caption('pygame Nmber 1!') Create a game loop that ill contine rnning throghot the game and check for eents. hile Tre: # main game loop for eent in pygame.eent.get(): x Check the eent type for exit eents like the close icon being clicked on the pygame indo. if eent.type == QUIT: pygame.qit() sys.exit() y No to test yor code. Sae yor code and then select 'Rn' from the men bar or press F5. Yo shold see a indo appear. If yo click the close icon of the indo, it shold close and the programme exits. Next: Defning Game Elements With Data

3 2. DEFINING GAME ELEMENTS WITH DATA To store the position of an alien ship defne x and y coordinates by setting them to a starting ale. Write this code near the top of yor programme. # Data alienx = 200 alieny = 20 Defne some constants that e can se for setting colors. BLACK = ( 0, 0, 0) WHITE = (255, 255, 255) RED = (255, 0, 0) GREEN = ( 0, 255, 0) BLUE = ( 0, 0, 255) No e can dra the alien ship onto the screen at the coordinates e hae defned. Make a fnction called drascreen and add a call to it in the game loop. # This goes in the game loop # Dra the screen drascreen() # This goes aboe the game loop def drascreen(): DISPLAYSURF.fill(BLACK) draalien() pygame.display.pdate() # This goes aboe the drascreen fnction def draalien(): x = alienx y = alieny points = [(x,y+10),(x-10,y-10),(x+10,y-10)] pygame.dra.lines(displaysurf,red,tre,points,1) Next: Animating the Alien Ship

4 3. ANIMATING THE ALIEN SHIP Create a fnction to moe the alien ship left and right. def moealien(): global aliendir, alienx, alieny if aliendir == 0: alienx = alienx - 1 if alienx == 0: aliendir = 1 if aliendir == 1: alienx = alienx + 1 if alienx == 400: aliendir = 0 We are sing a ne global ariable called aliendir so e need to defne that at the top of the code ith or other data. aliendir = 0 We also need to call the ne moealien fnction from or game loop. # Moe the alien moealien() x If yo try rnning the code, the alien ship ill probably moe too fast so e can slo don the animation like this: # Pt this before the game loop gameclock = pygame.time.clock() # Pt this jst inside the game loop gameclock.tick(20) Next: Adding A Player Ship

5 4. ADDING A PLAYER SHIP Add some global ariables at the top of yor code to hold the x and y co-ordinates of the player ship. shipx = 200 shipy = 280 Defne a fnction aboe yor game loop to dra the player ship. def draship(): x = shipx y = shipy points = [(x,y-10),(x-10,y+10),(x+10,y+10)] pygame.dra.lines(displaysurf,green,tre,points,1) Then add a call to the draship fnction in the drascreen fnction. def drascreen(): DISPLAYSURF.fill(BLACK) draalien() draship() pygame.display.pdate() x To listen for key presses e need to defne a fnction called checkkeys and add a call to it from the game loop. def checkkeys(): global shipx, shipy if pygame.key.get_pressed()[pygame.k_left]!=0 : shipx = shipx - 3 if pygame.key.get_pressed()[pygame.k_right]!=0 : shipx = shipx + 3 if pygame.key.get_pressed()[pygame.k_space]!=0 : firelaser() # Check keyboard inpt inside the game loop checkkeys() Next: Make a Laser Element

6 5. MAKE A LASER ELEMENT Defne a fnction called frelaser that e called in the checkkeys fnction. Pt this aboe the checkkeys fnction. def firelaser(): global lasery,laserx if lasery <= 0 : lasery = shipy laserx = shipx We hae sed some ne global ariables so e need to make sre they are inclded in the data section at the beginning of the code. laserx = 0 lasery = 0 No defne a fnction to dra the laser and add a call to the fnction in the drascreen fnction. def dralaser(): global laserx, lasery if lasery >= 1 : points = [(laserx,lasery+10),(laserx,lasery)] pygame.dra.lines(displaysurf,white,false,points,1) # This goes in the drascreen fnction dralaser() x We ill also need to defne a fnction to moe the laser p the screen hen it has been fred and then add a call to it in the game loop. def moelaser(): global lasery if lasery >=1 : lasery = lasery - 5 # This goes in the game loop moelaser() Next: Check if The Laser Hit the Alien Ship

6. CHECK IF THE LASER HIT THE ALIEN SHIP Defne a fnction to check if the laser co-ordinates are inside the bonding box of the alien ship and add a call to the fnction in the game loop.

checklaser() No test yor programme. Yo shold see a moing red triangle and a green triangle at the bottom of the screen. If yo se the arro keys left and right the green (player) ship shold moe.

7 6. CHECK IF THE LASER HIT THE ALIEN SHIP Defne a fnction to check if the laser co-ordinates are inside the bonding box of the alien ship and add a call to the fnction in the game loop. def checklaser(): global laserx,lasery,alienx,alieny if (laserx > alienx-10 and laserx < alienx+10 and lasery > alieny-10 and lasery < alieny+10) : alieny = -20 # This goes in the game loop checklaser() No test yor programme. Yo shold see a moing red triangle and a green triangle at the bottom of the screen. If yo se the arro keys left and right the green (player) ship shold moe. If yo hit the space bar yo shold see a laser fre from the player ship and moe p the screen. If the laser hits the red ship it shold disappear. Next Steps : Hae a go at coding the folloing items Mltiple alien ships Alien ships shoot back Mltiple lasers Score Alien ships moe diferently Use bitmap graphics for the ships Make explosion graphic hen a ship is hit Make sonds hen a laser is fred or a ship is hit Extra resorces for this project can be fond at:.technoisaledcation.co.k/pygame_orkshop Next: Python Cheat Sheet

8 PYTHON CHEAT SHEET Python Keyords def for in from global if import hile Defne a fnction ith optional ariables. Example: def frelaser(lasernmber): Make a loop to read an array. Example: for ale in array: Import a section of a modle for se in the programme. Example: from pygame.locals import * Enable changing the ale of ariables that hae been defned otside a fnction. Example: global x,y A condition statement. Rn the folloing code if the eqation is tre. Example: if lasery < 0: Import a modle so that its fnctions can be sed. Example: import sys Retrn control of the programme back to here the fnction as called from. Example: Perform a loop ntil an eqation is tre. Example: hile (cont < 10): Usefl PyGame Fnctions pygame.display.pdate() - refresh the indo to display changes. pygame.display.set_caption(title) - set the title of the indo. DISPLAYSURFACE = pygame.display.set_mode((idth,height)) - create a pygame indo. pygame.dra.lines(displaysurface,color,closed,points,idth) - dra lines beteen a point list. pygame.eent.get() - get a list of eents that hae happened. pygame.init() - Initialise the pygame modle. DISPLAYSURFACE.fll(color) - fll the indo ith a color. pygame.key.get_pressed()[key] - see if a named key is being pressed. pygame.time.clock() and tick(framespersecond) - set the frame rate for a game loop. pygame.qit() - close the pygame session. For an introdction to Python on the Raspberry Pi, Mark Vanstone has prodced a 'Getting Started' series of ideos that can be ieed at: This resorce prodced by TechnoVisal Edcation 2017 technoisaledcation.co.k

Worksheet And Programme Listing

GETTING STARTED WITH PYGAME ZERO ON THE RASPBERRY PI Worksheet And Programme Listing.technoisaledcation.co.k This resorce is copyright TechnoVisal Limited 2017 bt permission is gien to freely copy for