plants are recursive!

using L-Systems to generate
realistic plants

by Sher Minn Chong / @piratefsh at !!Con

Sher Minn

Malaysian

front-end web engineer

Recurse Center alum

plants & recursion

plants

recursion

```javascript // recursive fibonacci function function fib(n){ if(n == 0){ return 0; } if(n == 1){ return 1; } return fib(n-2) + fib(n-1); } // call it fib(4) ```

repetition in a self-similar way

example

koch snowflake

recursion in nature

Aristid Lindenmayer

algae cell growth

L-Systems

a string rewriting system

axiom	A
rules	A → AB B → A

axiom A rules A → AB B → A

n string 0 A 1 AB 2 ABA 3 ABAAB 4 ABAABABA

describing recursive patterns

string → drawing?

symbol	do thing
F	draw a line
+	rotate clockwise by angle
-	rotate counterclockwise by angle

describing plants

symbol	do thing
F	draw a line
+	rotate clockwise by angle
-	rotate counterclockwise by angle
[	save current state
]	restore saved state

introducing randomness

taking L-Systems further

Y = -FX-Y X = X+YF+	→
simple rules	→	beautiful paterns

resources

Algorithmic Beauty of Plants

Modelling Plants with L-Systems

L-Systems Turtle Graphics Renderer

demo code

end!

tweet at me
@piratefsh

demo: https://git.io/vwhe1 | slides: https://git.io/vwhvN