CS 151 Computational Thinking: Visual Media Applications
(Labs) Project 8
Due: Tuesday, April 11, 2017, 11:59 pm
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.)
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
'<' - 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()).
'>' - 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,
'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.
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.
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
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.
Have each tree exhibit some variation by modifying aspects of how it
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.
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
In the test main function the line:
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
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