CSC111 Lab 11 Solution Program

--D. Thiebaut 22:45, 15 April 2010 (UTC)

---

# lab11.py
# Solution program for Lab 11
# D. Thiebaut
# 
# This program creates a school of fish with a random number
# of fish (but at least 1).
# The fish have random horizontal speed and will move up and
# down at random as well.
# I created two kinds of fish using the "convert" utility.
#
# First I made a copy of fish15.gif and named it Lfish15.gif
#
#   copy fish15.gif Lfish15.gif
# 
# Then I "flopped" the fish to create a mirror image that
# goes in the opposite direction:
#
#   convert Lfish15.gif -flop Rfish15.gif
#
# The 'L' fish goes to the left, and the 'R' fish to the 
# right.
#
# Then when fish are created, the L fish are given negative
# dx speeds, and the R fish are given positive dx speeds.
#
import random
from graphics import *
H = 400
W = 400
 
class Fish:
    """the class for the fish"""
    def __init__( self, fileName, centerPoint, dx ):
        """constructor"""
        self.Image = Image( centerPoint, fileName )
        self.dx = dx

    def move( self ):
        """move the fish to the right using its own self.dx
        and move the fish up or down some random number of pixels"""
        ddy = [-1, -2, 1, 2, 0, 0, 0, 0, 0, 0, 0, 4]
        index = random.randrange( len( ddy ) )
        self.Image.move( self.dx, ddy[ index ] )

    def draw( self, win ):
        """draw the fish on the graphics window"""
        self.Image.draw( win )


def waitForClick( win, message ):
    """ waitForClick: stops the GUI and displays a message.  
    Returns when the user clicks the window. The message is erased."""
 
    # wait for user to click mouse to start
    startMsg = Text( Point( win.getWidth()/2, win.getHeight()/2 ), message )
    startMsg.draw( win )    # display message
    win.getMouse()          # wait
    startMsg.undraw()       # erase
 
 
def main():
    """the main program: creates a school of fish and moves them on the screen"""
    global H, W
    H = 399
    W = 266
    win = GraphWin( "Fish Tank", W, H )

    background = Image( Point( W/2, H/2 ), "tank2.gif" )
    background.draw( win )
    #waitForClick( win, "click to start" )
    
    #--- create a school of fish ---
    school = []
    for i in range( 1 + random.randrange( 5 ) ):
        if random.randrange( 20 )<10:
            f = Fish( "Rfish15.gif", Point( 30+i*20, 30+i*40 ), +1 + random.randrange( 3 ) )
        else:
            f = Fish( "Lfish15.gif", Point( 30+i*20, 30+i*40 ), -1 - random.randrange( 3 ) )

        f.draw( win )
        school.append( f )

    #--- move the fish around, 100 times ---
    for i in range( 100 ):
        for f in school:
            f.move()

        
    #--- we're done when the user clicks the window ---
    waitForClick( win, "click to end" )
    win.close()
 
main()