We are using JES in my intro programming class and I have run into roadblock for my lab. The program is supposed to allow a user to select a picture and then a moth(bug) will start at the center of the picture and make random movements and change pixels to white if they are not already to simulate eating. I am stuck on the movement part. the current program below will load and eat 1 pixel at the very center but make no other movements. Could someone give me a hint as to what I am doing wrong with my random movement calls?
from random import *
def main():
#lets the user pic a file for the bug to eat
file= pickAFile()
pic= makePicture(file)
show(pic)
#gets the height and width of the picture selected
picHeight= getHeight(pic)
picWidth= getWidth(pic)
printNow("The height is: " + str(picHeight))
printNow("The width is: " + str(picWidth))
#sets the bug to the center of the picture
x= picHeight/2
y= picWidth/2
bug= getPixelAt(pic,x,y)
printNow(x)
printNow(y)
color= getColor(bug)
r= getRed(bug)
g= getGreen(bug)
b= getBlue(bug)
pixelsEaten= 0
hungerLevel= 0
while hungerLevel < 400 :
if r == 255 and g == 255 and b == 255:
hungerLevel + 1
randx= randrange(-1,2)
randy= randrange(-1,2)
x= x + randx
y= y + randy
repaint(pic)
else:
setColor(bug, white)
pixelsEaten += 1
randx= randrange(-1,2)
randy= randrange(-1,2)
x= x + randx
y= y + randy
repaint(pic)
Looks like you're never updating the position of the bug within the loop. You change x and y, but this doesn't have any effect on bug.
Try:
while hungerLevel < 400 :
bug= getPixelAt(pic,x,y)
#rest of code goes here
Incidentally, if you have identical code in an if block and an else block, you can streamline things by moving the duplicates outside of the blocks entirely. Ex:
while hungerLevel < 400 :
bug= getPixelAt(pic,x,y)
if r == 255 and g == 255 and b == 255:
hungerLevel + 1
else:
setColor(bug, white)
pixelsEaten += 1
randx= randrange(-1,2)
randy= randrange(-1,2)
x= x + randx
y= y + randy
repaint(pic)