#! /usr/bin/python import sys, pygame # ===================================================================== # GLOBAL VARIABLES # - list all variables that need to be globally accessible # define the size of the pygame display window scrSize = scrWidth, scrHeight = 640,480 gameScreen = None # the main display screen backImage = None # the loaded background image scrRefreshRate = 40 # the pause (in milliseconds) between updates keepPlaying = True # flag to identify if the game should continue # ===================================================================== # SETUP ROUTINE # - initializes the pygame display screen and background image def gameSetup(): # specify the global variables the setup routine needs to access global gameScreen, scrSize, backImage # initialize pygame pygame.init() # initialize the display screen gameScreen = pygame.display.set_mode(scrSize) # load and display the background image backImage = pygame.image.load('backdrop.gif') gameScreen.blit(backImage, (0,0)) # ===================================================================== # GAME OBJECT # controls the basic movable in-game objects (ships in this case) # # Each game object has several properties: # # origImage: the loaded image to represent that object # image: the current display image for the object # (rotated and zoomed appropriately from the original) # position = x,y: the x,y coordinates of the object # facingDir: the direction the object is currently facing # velocity: the horizontal/vertical distance covered # by the object each game step # scale: the scaling (zoom) factor currently used for the object # selected: a true/false value indicating if the object is # currently selected # # Each game object also has several actions that can be applied to it: # # __init__ : the initialization routine for the object # update: the routine applied each step to update the # object's current location and image # changeFacing: a routine to provide a new facing direction # for the object # changeSpeed: a routine to increase or decrease the object's # current velocity # changeScale: a routine to zoom in/out on the object # (scaling the size of its image) class GameObject(pygame.sprite.Sprite): # the constructor (initialization routine) for the # movable game objects def __init__(self, image, x, y, direction, speed): # initialize a pygame sprite for the object pygame.sprite.Sprite.__init__(self) # load an image for the object self.origImage = pygame.image.load(image) self.image = self.origImage # set up the initial position for the object self.position = self.x, self.y = x, y # set up the initial direction for the object self.facingDir = direction # set up the initial scale (zoom) for the object self.scale = 1.0 # set up the initial speed for the object self.velocity = speed # initially treat the object as unselected self.selected = False # the update routine adjusts the object's current position and # image based on its speed and direction def update(self): # calculate the object's new position based on its old position, # and its current facing and velocity if (self.facingDir == 0): self.x = self.x + self.velocity self.y = self.y - self.velocity elif (self.facingDir == 90): self.x = self.x - self.velocity self.y = self.y - self.velocity elif (self.facingDir == 180): self.x = self.x - self.velocity self.y = self.y + self.velocity elif (self.facingDir == 270): self.x = self.x + self.velocity self.y = self.y + self.velocity self.position = self.x, self.y # update (rotate and zoom) the image for the object self.image = pygame.transform.rotozoom(self.origImage, self.facingDir, self.scale) # position the image correctly self.rect = self.image.get_rect() self.rect.center = self.position # the turning routine turns the ship 90 degrees clockwise if # the turning direction is right ('r') or 90 degrees # counterclockwise if the turning direction is left ('l') def changeFacing(self, dir): # if the direction is left then # turn the object 90 degrees counterclockwise if (dir == 'l'): self.facingDir = self.facingDir + 90 if self.facingDir >= 360: self.facingDir = self.facingDir - 360 # otherwise, if the direction is right then # turn the object 90 degrees counterclockwise elif (dir == 'r'): self.facingDir = self.facingDir - 90 if self.facingDir < 0: self.facingDir = self.facingDir + 360 # the speed change routine increases the object's velocity # if the change is '+', or decreases the velocity # if the change is '-' def changeSpeed(self, change): # if the change is '+' then double the current speed # (or increase to 1 if the speed used to be 0) if (change == '+'): self.velocity = self.velocity * 2 if self.velocity == 0: self.velocity = 1 # otherwise, if the change is '-' then cut the # current speed in half elif (change == '-'): self.velocity = self.velocity / 2 # the zoom routine zooms in on the object (makes it larger) # if the scale is '+' or zooms out (makes it smaller) # if the scale is '-' def changeScale(self, scale): # zoom in on the object if the scale is '+' if (scale == '+'): self.scale = self.scale * 1.25 # otherwise zoom out if the scale is '-' elif (scale == '-'): self.scale = self.scale / 1.25 # the object selection routine notifies the object # that it has just been selected or deselected def changeSelected(self, selFlag): # if the passed flag is True then store the fact that # this object is now the selected one if selFlag: self.selected = True # otherwise store the fact that this object is no # longer the selected one else: self.selected = False # ===================================================================== # EVENT HANDLING ROUTINE # - processes any pending in-game events, # returns which object is currently selected # (since this can be changed by some events) # the routine expects to be given a list of the game objects # currently available (objList) and which object is # currently selected/controlled by the player (selObj) def processEvents(objList, selObj): # specify which global variables the routine needs access to global keepPlaying # process each pending event for event in pygame.event.get(): # if the user closed the window set keepPlaying to False # to tell the game to quit playing if event.type == pygame.QUIT: keepPlaying = False # check if the user has pressed a key elif event.type == pygame.KEYDOWN: # the escape and q keys quit the game if event.key == pygame.K_ESCAPE: keepPlaying = False elif event.key == pygame.K_q: keepPlaying = False # the left and right arrows turn the currently selected ship # counterclockwise or clockwise, respectively elif event.key == pygame.K_LEFT: print 'turning left with ship ', selObj objList[selObj].changeFacing('l') elif event.key == pygame.K_RIGHT: print 'turning right with ship ', selObj objList[selObj].changeFacing('r') # the up and down arrows cause the currently selected ship # to speed up or slow down, respectively elif event.key == pygame.K_UP: print 'speeding up ship ', selObj objList[selObj].changeSpeed('+') elif event.key == pygame.K_DOWN: print 'slowing down ship ', selObj objList[selObj].changeSpeed('-') # the plus and minus keys zoom in/out on the currently # selected ship elif event.key == pygame.K_EQUALS: print 'zooming in on ship ', selObj objList[selObj].changeScale('+') elif event.key == pygame.K_MINUS: print 'zooming out on ship ', selObj objList[selObj].changeScale('-') # the tab key scrolls through the list of ships, # changing which one is currently selected elif event.key == pygame.K_TAB: objList[selObj].changeSelected(False) selObj = selObj + 1 if (selObj >= len(objList)): selObj = 0 objList[selObj].changeSelected(True) print 'selected ship ', selObj # return the currently selected object number # (may have been updated by one of the events processed) return selObj # ===================================================================== # MAIN GAME CONTROL ROUTINE # - sets up the game and runs the main game update loop # until instructed to quit def main(): # identify any global variables the main routine needs to access global gameScreen, backImage, scrRefreshRate, keepPlaying # initialize pygame and the game's display screen gameSetup() # create the list of screen update sections (rectangles) updateSections = None # create an array of objects to add to the display, # giving each of them # an image, xcoord, ycoord, facing, and speed gameObjList = [ GameObject('ship.gif', 80, 60, 270, 1), GameObject('ship.gif', 560, 60, 180, 2), GameObject('ship.gif', 560, 420, 90, 0) ] # indicate which game object is currently 'selected' selectedObj = 0 gameObjList[selectedObj].changeSelected(True) # create a group for the game objects objGroup = pygame.sprite.RenderUpdates(*gameObjList) # run the main game loop keepPlaying = True while keepPlaying: # handle any pending events # (processEvents needs the list of objects that might # be affected, and which object is currently selected) selectedObj = processEvents(gameObjList, selectedObj) # update the display of the object groups objGroup.clear(gameScreen, backImage) # run the updates on each object in the group objGroup.update() # update the display rectangles updateSections = objGroup.draw(gameScreen) # update the buffered display pygame.display.update(updateSections) # switch to the new display image pygame.display.flip() # pause before initiating the next loop cycle pygame.time.delay(scrRefreshRate) # ===================================================================== # INITIATE THE GAME # - calls the main() routine if __name__ == "__main__": main()