Notes:
Adding trees
import random class worldTreeGroup (pygame.sprite.Group): speed = 5 def __init__ (self, picture): pygame.sprite.Group.__init__(self) treePicture = picture treeRow = pygame.sprite.Group()
# in rows with a gap somewhere in the middle # only have a line of trees every 5th row or the # game is too difficult for y in range (0, 400): if (y % 5 == 0): # every 5th, add tree row with a gap gapsize = 3 + random.randint(0,6) # size of gap # starting position of gap gapstart = random.randint(0,10 - (gapsize//2)) # create a row of 20 trees but 'gapsize' # skip trees in the middle for b in range (0,20): if b >= gapstart and gapsize > 0: gapsize-=1 else : newtree=worldSprite([b*20, (y+10)*20], treePicture) treeRow.add(newtree) self.add(treeRow) def update (self): for treeRow in self: treeRow.rect.top-=self.speed if treeRow.rect.top <= -20: treeRow.kill() # remove this block from ALL groups
Now, if we can get rows of trees advancing on the skier’s position, this game will be a lot more challenging. Also if the skier hits a tree, the game should stop.
To set up the “piste”, this additional class sets up rows of trees that have a gap in the middle for the skier to pass through. The initialiser creates a group of trees by using the picture it is given and adding it a number of times (leaving a gap) to a group representing a row of trees. It then adds that group to the larger group representing a group of tree rows. Notice the use of integer division, “//”, to divide the “gapsize”. Without it, dividing gapsize by 2 may give a half and not a whole number (an integer ). The update part of the class defines what a group of trees can do when it is updated. The group will take all the rows of trees within it and move them up by a small distance. Also, when the row of trees goes behind the skier, off the top of the screen, it will remove that row of trees.
Experiments in Python
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