CSC111 Homework 11 2011

--D. Thiebaut 17:50, 6 December 2011 (EST)

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Traffic Light Problem: Part 1

• Create a class for a traffic light that can be drawn on the graphics window, with the bus/car and the trees.
• The traffic light is simply a tall long rectangle with three circles inside, one which is either black or yellow, one that is either black or green, and one that is either black or red.
• Your class should contain methods that should allow objects instantiated from it to
  • Turn the green light on. This will set the other ones off (i.e. black)
  • Turn the yellow light on. This will set the other ones off (i.e. black)
  • Turn the red light on. This will set the other ones off (i.e. black)
• The default mode is for TrafficLight objects to be created with the green light on.

• Test your program and make sure you can draw a traffic light and control it in some ways. Below is an example of how you could test this:

def main():
      win = GraphWin( "Hw 11 - 111b-xx", W, H )
      x = ...
      y = ...
      light = TrafficLight( Point( x, y ) )
      light.draw( win )

      click = 0
      while  True:
                   
          if win.checkMouse() != None:
               click = ( click + 1 ) % 3
               if click == 0:  light.setGreenOn()
               if click == 1:  light.setYellowOn()
               if click == 2:  light.setRedOn()
    
      win.close()

main()

Part 2

• Same as Part 1, but the TrafficLight object will now switch on its own from green to yellow, from yellow to red, and from red back to green.

• The way to do that is for the traffic light class to contain a counter, and every time it is called to update itself, it increments a counter. If the counter passes a particular threshold, say 10, it decide to turn on anther light.
• There should be a car (or bus) going around the window, wrapping around the window as it leaves one edge and reappearing on the other side.
• There should be trees around as well.
• The car should stop if it is within 50 pixels in front of the traffic light and the light is red or yellow. Otherwise the car moves on...
• Here is an example below of what your main program could look like:

position = Point( ..., ... )
light = TrafficLight( position )
light.draw( win )
car = Car( ... )
car.draw( win )

while True:
    light.update()

    if ( not light.isGreen() ) and car.distanceFrontTo( light.getPosition() ) <= 50 :
          car.move( )