Due: Tuesday, April 4, 2017, 11:59 pm

Fractals and Trees

The assignment is to bring together the lsystem and turtle_interpreter pieces to make a scene that consists of fractal shapes, trees, and other turtle graphics (think back to projects 1, 2 and 3). Your top-level program will include both the lsystem and turtle_interpreter modules.


  1. Create a file called abstract.py. The file will need to import sys, turtle, lsystem, and turtle_interpreter. Write a function that creates an abstract image using L-systems. This image should be constructed to take advantage of your Python programming skills -- don't rely wholly on the random package and a loop. Your goal should be complexity, yet order in your image and simplicity in your code. One idea is to make an interesting pattern.

    Your image should include at least three different L-systems, with at least one of them using brackets. Don't feel beholden to use the suggested number of iterations or angles for any L-system. Please avoid use any command-line arguments, such as file names or angles or distances or iterations. Instead, you should hard code those values in your main program. It is easiest for us to test your files if we don't have to worry about using the correct command-line arguments.

    In your image function, you can use turtle commands to pick up the pen, move it to a new location, change colors, change pen widths, and put down the pen before drawing a new shape.

    A picture with 3 different L-systems is required image 1.

  2. Make a new file grid.py that contains a function that draws a set of 9 trees based on the systemB L-system, or some variation of it that has brackets. Order the 9 trees as a 3x3 grid. From left to right the number of iterations of the L-system should go from 1 to 3. From top to bottom, the angle of the L-system should be 22, 46, and 60. Use a double for-loop to create the grid. Note: Again, please avoid use any command-line arguments in your program.

    A picture with a grid of L-systems is required image 2.

  3. Make a new file scene.py that makes a non-abstract scene with two or more objects generated using L-systems. The scene must include at least one new L-system with brackets (e.g. a tree) that you haven't used yet. You can use one of the L-systems from ABOP (look at pages 9, 10, and 25 for single-rule L-systems) or make up one of your own. The scene does not need to be complex, but your code should exhibit modularity and good design. Note: Again, please avoid use any command-line arguments in your program.

    A scene that includes 2 different L-systems is required image 3.


Write-up and Hand-in

Turn in your code by putting it into your private hand-in directory on the Courses server. All files should be organized in a folder titled "Project 7" and you should include only those files necessary to run the program. We will grade all files turned in, so please do not turn in old, non-working, versions of files.

Make a new wiki page for your assignment. Put the label cs151s17project7 in the label field on the bottom of the page. But give the page a meaningful title (e.g. Ying's Project 7).

In general, your intended audience for your write-up is your peers not in the class. Your goal should be to be able to use it to explain to friends what you accomplished in this project and to give them a sense of how you did it. Follow the outline below.

To check whether you've made your images and their text clear, you may ask yourself the following questions:

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