From b0b087dd5e92c6103d8da26b4bacd0e44015e057 Mon Sep 17 00:00:00 2001
From: Simon Brooke <simon@journeyman.cc>
Date: Mon, 1 Sep 2025 21:44:31 +0100
Subject: [PATCH] Added koch curve.

---
 index.html | 81 ++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 51 insertions(+), 30 deletions(-)
diff --git a/index.html b/index.html
index f785a56..0d97841 100644
--- a/index.html
+++ b/index.html
@@ -7,7 +7,7 @@
     <body>
         <h1>Tittle: Turtles in <a href="https://github.com/babashka/scittle/tree/main">Scittle</a></h1>
         <svg id="playing-field"
-            stype="width: 800; height: 900"
+            style="width: 100%; height: 900"
             version="1.1"
             width="800"
             height="900"
@@ -15,8 +15,9 @@
             xmlns:svg="http://www.w3.org/2000/svg">
 
         </svg>
+        <form><label for="repl">&gt;</label><input type="text" size="80" id="repl"></form>
         <script type="application/x-scittle">
-            (def turtle (atom {:theta 0 :x 0 :y 0 :pen :up :ink "blue"}))
+            (def turtle (atom {:theta 0 :x 0 :y 0 :pen :up :nib 3 :ink "blue"}))
 
             (defn log-turtle! 
                 []
@@ -71,14 +72,10 @@
 
             (defn turn-to! 
                 "Turn the turtle to face `angle`, expressed in degrees with respect to the
-                X axis. If `angle` is not a number, throw an exception.
-                
-                **TODO**: Note that 180&deg; is currently straight up; this is not intended, it 
-                is intended that 0&deg; should be straight up, and this change will be made 
-                before version 1.0."
+                X axis. If `angle` is not a number, throw an exception."
                 [angle]
                 (if (number? angle)
-                    (swap! turtle assoc :theta (sanitise-angle angle))
+                    (swap! turtle assoc :theta (sanitise-angle (+ 180 angle)))
                     (not-a-number! angle))
                 (.info js/console (str "(turn-to! " angle 
                                         ") :: :theta now " (:theta @turtle))))
@@ -131,23 +128,29 @@
                             (.appendChild playing-field elt)))
                     (swap! turtle assoc :x x :y y))))
 
+            (defn centre! 
+                "Move the turtle to the centre of the playing field."
+                []
+                (let [box (.getBoundingClientRect 
+                            (.getElementById js/document "playing-field"))
+                      w (.-scrollWidth box)
+                      h (.-scollHeight box)]
+                      (move-to! (/ w 2) (/ h 2))
+                      (turn-to! 0)))
+
             (def ^:const pi 3.141592653589793)
 
             (defn degrees->radians
                 "Return the equivalent, in radians, of this `angle` espressed in degrees"
                 [angle]
-                (let [v (when (number-or-error! angle)
-                            (* angle (/ pi 180)))]
-                    (.log js/console (str "(degrees->radians " angle ") => " v))
-                    v))
+                (when (number-or-error! angle)
+                    (* angle (/ pi 180))))
 
             (defn radians->degrees
                 "Return the equivalent, in degrees, of this `angle` espressed in radians"
                 [angle]
-                (let [v (when (number-or-error! angle)
-                        (/ (* angle 180) pi))]
-                    (.log js/console (str "(radians->degrees " angle ") => " v))
-                    v))
+                (when (number-or-error! angle)
+                    (/ (* angle 180) pi)))
 
             (defn sin 
                 "Return the sine of this `angle`, considered to be expressed in degrees."
@@ -174,7 +177,6 @@
                 (when (string? colour)
                     (swap! turtle assoc :ink colour)))
 
- 
             (defn set-nib!
                 "Set the nib (width) of the pen to this `n`, which should be a number."
                 [n]
@@ -246,21 +248,40 @@
                             (when (< side sides)
                                 (recur (inc side))))
                         (pen-up!))))
-                
+
+
+            (defn koch
+                [length depth]
+                (pen-down!)
+                (.info js/console (str "(koch " length " " depth ")"))
+                (let [l' (/ length 3)
+                      d' (dec depth)
+                      i (= depth 1)]
+                    (if i (move! l') (koch l' d'))
+                    (turn! -60)
+                    (if i (move! l') (koch l' d'))
+                    (turn! 120)
+                    (if i (move! l') (koch l' d'))
+                    (turn! -60)
+                    (if (= depth 1) (move! l') (koch l' d'))))                        
+
             (log-turtle!)
             (pen-up!)
-            (log-turtle!)
-            (move-to! 350 500)
-            (log-turtle!)
-            (doall (map #(let [v (* 16 (mod % 16))
-                                c (str "rgb(" v "," 128 "," (- 256 v)")")]
-                                (set-ink! c)
-                                (draw-polygon! % 100)) 
-                        (range 3 24)))
-            (turn-to! 180)
-            (set-ink! "blue")
-            (set-nib! 2)
-            (draw-tree! 100 20 16 8 0.2 0.8 9)
+            (move-to! 400 0)
+            (set-nib! 1)
+            (koch 800 5)
+
+;;            (doall (map #(let [v (* 16 (mod % 16))
+;;                                c (str "rgb(" v "," 128 "," (- 256 v)")")]
+;;                                (set-ink! c)
+;;                                (draw-polygon! % 100)) 
+;;                        (range 3 24)))
+;;            (turn-to! 180)
+;;            (set-ink! "blue")
+;;            (set-nib! 2)
+;;            (draw-tree! 100 20 16 8 0.2 0.8 9)
+
+
         </script>
     </body>
 </html>
\ No newline at end of file
