CS21 Lab5: More Functions

The goal of this assignment is to continue practicing with functions. However, for this assignment you will need to decide for yourself how to break up the problem into reasonable functions. Remember that two key benefits of functions are that they reduce code duplication and create reusable modules.

You will use the graphics library to construct a program that animates two related stick figures by alternately drawing, undrawing, and moving the two figures. This will create a more interesting style of movement than we have seen previously. For example, the first stick figure could be drawn with arms and legs pointing down. The second stick figure could be drawn with arms pointing up and legs pointing out. This will create an animation that appears to do jumping jacks across the graphics window.

A skeleton version of the program, called stickFigures.py will appear when you run update21 in a terminal window. The program handin21 will only submit files in this directory.

You may work with a partner on this assignment. If you choose to do this, be sure to put both names at the top of your file. Only one student needs to turn in the solution using handin21.

• The user should draw the first stick figure. It should be undrawn and redrawn in gray so that it remains visible while the user draws the second stick figure (as shown below).

• Before starting the animation, undraw both figures and move them to the far left side of the graphics window. This can be accomplished by finding the center point of the head, determining how far the X component is from position 0, and then moving each part that distance to the left.
• To create the animation repeatedly do the following:

  draw figure1
  sleep
  undraw figure1
  move figure1 right
  draw figure2
  sleep
  undraw figure2
  move figure2 right  
  

  When the center of figure1's head goes beyond the right edge of the graphics window, the window should close and the program should end.
• The user should draw each stick figure by using the mouse in the following way:
  1. Indicate the center point of the head.
  2. Indicate the radius of the head.
     Note that given two points (x1, y1) and (x2, y2), you can determine the distance between them using the formula: sqrt( square(x2-x1) + square(y2-y1) )
  3. Indicate the starting and ending point of each of the following: body, left arm, right arm, left leg, and right leg.
  Each of these steps should be accompanied by text instructions displayed in the graphics window.

Once you are satisfied with your program, hand it in by typing handin21 in a terminal window. Remember, if you are working with a partner, only one of you needs to turn in the program.