adding more l-system examples

dragon.ld

@@ -0,0 +1,47 @@
+& Example Ludus implementation of the Dragon curve.
+& https://en.m.wikipedia.org/wiki/L-system#Example_6:_dragon_curve
+
+& variables : F G
+& constants : + -
+& start  : F
+& rules  : (F -> F+G), (G -> F-G)
+& angle  : 90°
+& F and G both mean "draw forward", + means "turn left by angle", and − means "turn right by angle"
+
+& set a length for each segment
+let length = 10
+
+& set an angle for all turns, default to 1/3 for triangles
+let angle = 0.25
+
+fn f!
+
+& define 'G' function from the grammaer
+fn g! {
+  (0) -> fd!(length)
+  (n) -> {
+    f!(dec(n))
+    rt!(angle)
+    g!(dec(n))
+  }
+}
+
+& define 'F' function from the grammaer
+fn f! {
+  (0) -> fd!(length)
+  (n) -> {
+    f!(dec(n))
+    lt!(angle)
+    g!(dec(n))
+  }
+}
+
+& this function defines the starting pattern.
+& each of the f! and g! calls expand based on the grammar at the top of this example
+fn dragon! (times) -> {
+  f!(times)
+}
+
+& call the base function with a number of iterations
+& remember, this is exponential! high numbers can freeze your browser.
+dragon!(10)

koch.ld

@@ -1,4 +1,13 @@
-& koch curve
+& Example Ludus implementation of the Dragon curve.
+& https://en.m.wikipedia.org/wiki/L-system#Example_4:_Koch_curve
+
+& A variant of the Koch curve which uses only right angles.
+& variables : F
+& constants : + −
+& start  : F
+& rules  : (F -> F+F−F−F+F)
+& Here, F means "draw forward", + means "turn left 90°", and − means "turn right 90°"
+
 
 let length = 10
 let angle = 0.25

sierp.ld

@@ -3,10 +3,11 @@
 
 & The Sierpinski triangle drawn using an L-system
 & variables : F G
-& constants : + −
+& constants : + -
-& start  : F−G−G
+& start  : F-G-G
-& rules  : (F → F−G+F+G−F), (G → GG)
+& rules  : (F -> F-G+F+G-F), (G -> GG)
 & angle  : 120°
+& F and G both mean "draw forward", + means "turn left by angle", and − means "turn right by angle".
 
 & set a length for each segment
 let length = 10

spiralgon.ld

@@ -1,46 +0,0 @@
-let gons = 10
-let sides = 4
-let size = 50
-
-fn randcolor () -> (random(0,255), random(0,255), random(0,255))
-
-fn ngon! (sides, size) -> {
-  repeat sides {
-    fd! (size)
-    rt! (inv(sides))
-  }
-  :gon!
-}
-
-fn spiralgon_recursive! (num, sides, size) -> {
-  pencolor!(randcolor())
-  ngon! (sides, size)
-
-  if gt? (num, 0) then {
-    rt!(inv(gons))
-    spiralgonr!(dec (num), sides, add(10,size))
-  } else {
-    :tired!
-  }
-}
-
-& Non recursive version using loop for reference/example
-& fn spiralgon! (num, sides) -> {
-&   loop (15, 0) with (size, times) -> {
-&     if lt? (times, num) then {
-&       pencolor!(randcolor())
-&       ngon! (sides, size)
-&       rt! (0.2)
-&       if gt? (times, div (num, 2)) then {
-&         fd! (20)
-&       } else {
-&         back! (200)
-&       }
-&       recur (add (size, 1), inc (times))
-&     } else :dizzy
-&   }
-& }
-
-
-
-spiralgon_recursive!(gons, sides, size)