pool table
# Simulate a pool ball bouncing off the cushions.
def pool():
w = 640 # Width of table
h = 480 # Height of table
xRate = 20 # Speed ball moves from left to right (pixels per frame)
yRate = 24 # Speed ball moves from top to bottom (pixels per frame)
size = 30 # Dimensions of square "ball"
# Ball bounces when its trailing edge gets to edge
right = w-size
bottom = h-size
# You can change the ball's color from run to run, so that you can just view the
# thumbnails of the frames as they are generated. Old thumbnails from previous
# runs of the program will have different colored ball, so can be easily distinguished.
color = red
# Generate 99 frames with ball in slightly different position.
for frameNumber in range(1,100):
# Create a pool table canvas & let's color it green
table = makeEmptyPicture(w, h)
addRectFilled(table, 0, 0, w, h, green)
# x,y location is displaced depending on how far into the movie we are.
# The part after the % was not shown in class and will be explained on Friday
x = (frameNumber*xRate)%(2*right)
y = (frameNumber*yRate)%(2*bottom)
# Keep the ball on the table
if x > right: # Too far right
x = x - 2*(x - right) # Reflect left ("bounce off the right cushion")
if y > bottom: # Too far down
y = y - 2*(y - bottom) # Reflect up ("bounce off the bottom cushion")
if x < 0: # Too far left
x = abs(x) # Reflect down ("bounce off top cushion")
if y < 0: # Too far up
y = abs(y) # Reflect up ("bounce off lower cushion")
# Now draw the ball in the calculated position
addRectFilled(table, x, y, size, size, color)
# And write this frame of the movie
frameString = str(frameNumber)
if frameNumber < 10:
frameString = "0" + frameString
writePictureTo(table, getMediaPath("pool" + frameString + ".jpg"))
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