Project 8: Better Trees
As with last week, the assignment is to bring together the lsystem and interpreter classes to make a scene that consists of fractal shapes and trees. Your top-level program will include both the lsystem and interpreter modules. Unlike last week, however, your scene.py may not include the turtle module or make any calls to turtle commands. If you want to draw something, you have to pass a string to the interpreter drawString function. 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.)
In the Lsystem class create a method def __str__(self) that
returns a nicely formatted string that might look like the following
base X rule X -> F-[[X]+X]+F[+FX]-Xl rule F -> FF
The __str__ function 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__ function 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:
should print out your nicely formatted string instead of the generic class instance string when you run your lsystem.py file.
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 in
drawString. For task 2, modify your drawString function so that it
supports four additional characters in the strings.
- '<' - 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 duple of colors. You should append just the first element of the duple 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, 0.3) ).
- 'r' - set the turtle's color to red ( e.g. (0.7, 0.2, 0.3) ).
Create a file task1.py. Have the file import lsystem and interpreter
(the new versions). Make a function that creates a simple image with
at least two different multi-rule L-systems. See if you can draw the
base string and rule below the corresponding picture.
This is required image 1.
Create a file task2.py and write a function that makes a forest or garden of flowers that includes L-systems with leaves or other ornaments that make use of the color store/restore. 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.
systemCL systemDL systemEL systemFL systemGL
This is required image 2.
Make two new L-systems. They can be variations on one of the ones
provide, and L-system from the ABOP book, or one you create ones 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 task3.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.
This is required image 3.
- 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 interpreter. For each new symbol, you will need another elif case in your drawString function. Avoid, if possible, setting colors, widths, or other attributes explicitly inside the drawString function.
- 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 interpreter's drawString function.
Make a new wiki page for your assignment. Give the page a useful title using English words. Put the label cs151f12project8 in the label field at the bottom of the page. Each of you needs to make your own writeup.
In addition to making the wiki page writeup, put the python files you wrote on the Courses server in your private handin directory.
In general, your writeup should 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 short code snippets in your description to point out relevant features. Note any unique computational solutions you developed.
- 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.
- Don't forget to label your writeup so that it appears in the listing on the main wiki page for the course. For this lab, use the label cs151f12project8