# L system rules for drawing corals
**URL:** https://discourse.processing.org/t/l-system-rules-for-drawing-corals/12733
**Category:** Coding Questions
**Created:** [July 15, 2019, 10:26pm UTC](https://discourse.processing.org/t/l-system-rules-for-drawing-corals/12733 "2019-07-15T22:26:47Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@MustafaMerza](https://discourse.processing.org/u/MustafaMerza)
#### Post date: [July 15, 2019, 10:26pm UTC](https://discourse.processing.org/t/l-system-rules-for-drawing-corals/12733/1 "2019-07-15T22:26:47Z")
Hello guys,
I’m sorry that I’m posting here but I haven’t found any other solution for my problem.
I’m using an example code for L-System that comes when downloading examples from “The Nature of Code by Daniel Shiffman” in my version which is 3.5.3
My main problem is that I need to generate images of corals but I need the rewriting rules for the L-System to generate those images.
Could anyone help me?
This is a my code for the main class
```auto
LSystem lsys;
Turtle turtle;
void setup() {
size(500, 500);
Rule[] ruleset = new Rule[3];
ruleset[0] = new Rule('A', "[B][B]C");
ruleset[1] = new Rule('B', "+H+H+H+H+H\"A");
ruleset[2] = new Rule('C', "T-H-H-H-H\"A");
lsys = new LSystem("A", ruleset);
turtle = new Turtle(lsys.getSentence(), height/2, radians(7));
}
void draw() {
background(255);
fill(0);
text("Click mouse to generate", 10, height-10);
translate(width/2, height);
rotate(-PI/2);
turtle.render();
noLoop();
}
int counter = 0;
void mousePressed() {
if (counter < 10) {
pushMatrix();
lsys.generate();
turtle.setToDo(lsys.getSentence());
turtle.changeLen(0.7);
popMatrix();
redraw();
counter++;
}
}
```
- Class LSystem
```auto
class LSystem {
String sentence; // The sentence (a String)
Rule[] ruleset; // The ruleset (an array of Rule objects)
int generation; // Keeping track of the generation #
// Construct an LSystem with a startin sentence and a ruleset
LSystem(String axiom, Rule[] r) {
sentence = axiom;
ruleset = r;
generation = 0;
}
// Generate the next generation
void generate() {
// An empty StringBuffer that we will fill
StringBuffer nextgen = new StringBuffer();
// For every character in the sentence
for (int i = 0; i < sentence.length(); i++) {
// What is the character
char curr = sentence.charAt(i);
// We will replace it with itself unless it matches one of our rules
String replace = "" + curr;
// Check every rule
for (int j = 0; j < ruleset.length; j++) {
char a = ruleset[j].getA();
// if we match the Rule, get the replacement String out of the Rule
if (a == curr) {
replace = ruleset[j].getB();
break;
}
}
// Append replacement String
nextgen.append(replace);
}
// Replace sentence
sentence = nextgen.toString();
// Increment generation
generation++;
}
String getSentence() {
return sentence;
}
int getGeneration() {
return generation;
}
}
```
- Class Rule
```auto
class Rule {
char a;
String b;
Rule(char a_, String b_) {
a = a_;
b = b_;
}
char getA() {
return a;
}
String getB() {
return b;
}
}
```
- Class Turtle
```auto
// The Nature of Code
// Daniel Shiffman
// http://natureofcode.com
class Turtle {
String todo;
float len;
float theta;
Turtle(String s, float l, float t) {
todo = s;
len = l;
theta = t;
}
void render() {
stroke(0, 255);
strokeWeight(2);
for (int i = 0; i < todo.length(); i++) {
char c = todo.charAt(i);
if (c == 'F' || c == 'T' || c == 'H' || c == '"') {
line(0, 0, len, 0);
translate(len, 0);
} else if (c == '+') {
rotate(theta);
} else if (c == '-') {
rotate(-theta);
} else if (c == '[') {
pushMatrix();
} else if (c == ']') {
popMatrix();
}
}
}
void setLen(float l) {
len = l;
}
void changeLen(float percent) {
len *= percent;
}
void setToDo(String s) {
todo = s;
}
}
```
And it gives me the image which is on the left.
But I need to be able to generate something like these corals on the rigth
---
### Author:  [@Chrisir](https://discourse.processing.org/u/Chrisir)
#### Post date: [July 15, 2019, 10:44pm UTC](https://discourse.processing.org/t/l-system-rules-for-drawing-corals/12733/2 "2019-07-15T22:44:25Z")
Can you show your code please?
What is your problem?
What does the code do now and what do you want it to do instead?
---
### Author:  [@MustafaMerza](https://discourse.processing.org/u/MustafaMerza)
#### Post date: [July 15, 2019, 11:14pm UTC](https://discourse.processing.org/t/l-system-rules-for-drawing-corals/12733/3 "2019-07-15T23:14:40Z")
Okay sorry for the first post, I’ve updated my post to provide more explanation.
---
### Author:  [@monkstone](https://discourse.processing.org/u/monkstone)
#### Post date: [July 16, 2019, 6:32am UTC](https://discourse.processing.org/t/l-system-rules-for-drawing-corals/12733/4 "2019-07-16T06:32:47Z")
I don’t know whether it is any use to you, but I wrote a library for generating [LSystems on processing](https://github.com/monkstone/LSystems). I explore with examples the various types of LSystems that can be produced vis:-
1. Context sensitive
2. Stochastic
3. Simple grammar
What I do recommend is this reference [http://algorithmicbotany.org/papers/#abop](http://algorithmicbotany.org/papers/#abop), and by the way good luck.