Elm – fun with L-System (Part 6)

Series:

1. Algae
2. Pythago­ras Tree
3. Can­tor Dust
4. Koch Curve
5. Sier­pin­ski Triangle
6. Dragon Curve (this)
7. Frac­tal Plant

Last time out we imple­mented the Sierpinski Triangle exam­ple from the L-System wikipedia page. Now, let’s con­tinue our jour­ney and see how we can imple­ment the (rather impressive sounding) Dragon Curve exam­ple in Elm.

 

Example 6 : Dragon Curve

First, let’s define our L-System:

Again, thanks to the work we did in Part 4, our work here is rather simple:

which is a pretty straight translation of:

• ‘F’ : draw forward
• ‘–’ : turn left 90 degrees
• ‘+’ : turn right 90 degrees
• ‘X’ and ‘Y’ : ignore

Unlike the other L-Systems, this one grows much slower and as it slows it does make a nice picture!

 

Live Demo (here)

Use LEFT and RIGHT arrow keys to evolve/devolve the L-System.

Source Code (here)

 

 

Next : Fractal Plant

 

Links

• Source code for this post
• Live demo