From cf61c25302bb3c8fcd110dfdc48d2b065ee74f63 Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Wed, 15 Apr 2020 16:21:14 +0800
Subject: [PATCH] add fern

---
 examples/lsystem2_collection.scad | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/examples/lsystem2_collection.scad b/examples/lsystem2_collection.scad
index e6129d1f..2276ca45 100644
--- a/examples/lsystem2_collection.scad
+++ b/examples/lsystem2_collection.scad
@@ -1,7 +1,7 @@
 use <experimental/lsystem2.scad>;
 use <line2d.scad>;
 
-for(line = tree()) {
+for(line = fern()) {
     line2d(
         line[0],
         line[1],
@@ -11,6 +11,17 @@ for(line = tree()) {
     );
 }
 
+function fern(n = 8, angle = 4, leng = 1, heading = 0, start = [0, 0]) = 
+    let(
+        axiom = "EEEA",
+        rules = [
+            ["A", "[++++++++++++++EC]B+B[--------------ED]B+BA"],
+            ["C", "[---------EE][+++++++++EE]B+C"],
+            ["D", "[---------EE][+++++++++EE]B-D"]
+        ]
+    )
+    lsystem2(axiom, rules, n, angle, leng, heading, start, forward_chars = "ABCDE");  
+
 function tree(n = 2, angle = 36, leng = 1, heading = 0, start = [0, 0]) = 
     let(
         axiom = "F",