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

Better Trees

As with last week, the assignment is to bring together the lsystem and turtle interpreter classes to make a scene that consists of fractal shapes and trees. Your top-level program will import both the lsystem and turtle_interpreter modules. Unlike last week, however, your main programs (arrangement.py and growth.py) may not import the turtle module or make any calls to turtle commands directly. If you want to draw something, you have to pass a string to the interpreter drawString method. There will be no exceptions to that rule. (Note that you may attach arbitrary meaning to any character not used by an L-system grammar.)

Tasks

1. We want to be able to change the color of elements in an Lsystem without affecting the color of other elements. We would also like to avoid setting colors, widths, or other turtle drawing features by adding new parameters to drawString. Modify your drawString method so that it supports five additional characters in the strings. Don't forget to update the docstring of drawString to include the new characters

   • '<' - the left angle bracket should push the current turtle color onto a color stack. You'll need to create a separate colorstack variable similar to the one used for position and heading. You can use the function turtle.color() to get the turtle's current color. Note that this function returns a tuple of colors. You should append just the first element of the tuple onto the color stack (e.g. turtle.color()[0]).
   • '>' - the right angle bracket should pop the current turtle color off the color stack and set the turtle's color to that value.
   • 'g' - set the turtle's color to green ( e.g. (0.15, 0.5, 0.2) ).
   • 'y' - set the turtle's color to light yellow ( e.g. (0.8, 0.8, 0.3)) .
   • 'r' - set the turtle's color to red ( e.g. (0.7, 0.2, 0.3) ).

   Once you have made the modifications to drawString, try running systemFL using the classtest.py test function from the lab. You can also use the test function single.py to draw just a single tree.

2. Create a file arrangement.py. Have the file import lsystem and turtle_interpreter (the new versions). Write a function that makes an arrangement of trees or flowers. The scene should include some multi-rule L-systems with leaves or other ornaments that make use of the color store/restore. You can use the symbol L to indicate a leaf, which could be drawn as a semicircle or a circle or a line. The following are variations with leaves and flowers, all defined by strings (no special characters except L). Try to include L-system trees with different numbers of iterations.

   At least two of the L-systems you use must have at least 2 rules. Like last week, please hard-code the filenames for the L-systems into your code, so that we can run your program without needing command line arguments.

   systemCL	systemDL	systemEL	systemFL	systemGL

   This is required image 1.

3. Make two new L-systems. They can be variations on one of the ones provided, an L-system from the ABOP book, or one you create on your own. The L-systems of interest are given in the ABOP book chapter 1, pages 10, 11, and 25.

   If you use a variation, include both the original and your variant in your writeup. (The difference does not have to be large.)

   In the file growth.py, create a scene function that makes an image using your L-systems after 2, 3, and 4 iterations. Note, if using a different pattern of iterations is more interesting (e.g. 4, 5, 6) you are free to use a different set of three iteration values. Indicate what you used in your writeup.

   Again, please hard-code the filenames for the L-systems into your code, rather than rely on command-line arguments. Also, be sure to put a copy of your new L-system's text file on the Courses server when you turn in your code.

   This is required image 2.

Extensions

• Have each tree exhibit some variation by modifying aspects of how it is drawn.
• Add leaves, berries, or color to your trees by adding symbols to the rules and cases to your turtle interpreter. For each new symbol, you will need another elif case in your drawString method.

• In the Lsystem class create a method def __str__(self) that returns a nicely formatted string that might look like the following when printed.

    base X
    rule X -> F-[[X]+X]+F[+FX]-X
    rule F -> FF
  

  The __str__ method gets called automatically when an object is printed out. It's also called to implement casting an object to a string using str(thing). Note that your __str__ method should not print anything out. It should build a string from the information in your L-system and return the string. Remember that '\n' is how you create a newline character.

  In the test main function the line:

  print lsys

  should print out your nicely formatted string instead of the generic class instance string when you run your lsystem.py file.

  See if you can draw the base string and rule below the image of a tree from that L-system.

• Get fancy with required images 2 or 3. Note that fancy means using programming structures (functions, loops, conditionals, lists, or math) to make a more interesting scene.
• Make more L-systems.
• Demonstrate that you can create other kinds of shapes (like squares, triangles, etc) by passing strings to the turtle interpreter's drawString method.

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 8" 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 cs151s17project8 in the label field on the bottom of the page. But give the page a meaningful title (e.g. Ying's Project 8).

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.

• A brief summary of the task, in your own words. This should be no more than a few sentences. Give the reader context and identify the key purpose of the assignment.
• A description of your solution to the tasks, including any images you created. This should be a description of the form and functionality of your final code. You may want to incorporate code snippets in your description to point out relevant features. Note any unique computational solutions you developed. Code snippets should be small segments of code--usually less than a whole function--that demonstrate a particular concept. If you find yourself including more than 5-10 lines of code, it's probably not a snippet. You should not include all your code in the writeup
• A description of any extensions you undertook, including images demonstrating those extensions. If you added any modules, functions, or other design components, note their structure and the algorithms you used.
• A brief description (1-3 sentences) of what you learned.
• A list of people you worked with, including TAs, and professors. Include in that list anyone whose code you may have seen, such as those of friends who have taken the course in a previous semester.
• Don't forget to label your writeup so that it is easy for others to find. For this lab, use cs151s17project8

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

• Does the text describe the content of the image?
• Does the text describe how the content was generated? (this will be relevant if the image is of a drawing that was created by a program or of data that was collected or analyzed by your code).
• Does the text describe any implications of the content? (e.g. if the content is results from a simulation, does it analyze the results. This may not be relevant in CS151.)
• If the image contains data, are the data properly labeled? (This may not be relevant in CS151.)
• If the image contains a lot of parts (e.g. the screen dump of a lot of numbers), are the most important parts highlighted in some way? (I.e. is the image or graph too cluttered or does it tell a clear story?)

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