Add example with ellipse rotation

examples/dune

@@ -48,6 +48,11 @@
  (modules rotate)
  (libraries joy))
 
+(executable
+ (name rotate_ellipse)
+ (modules rotate_ellipse)
+ (libraries joy))
+
 (executable
  (name line)
  (modules line)
@@ -127,4 +132,3 @@
  (name smile)
  (modules smile)
  (libraries joy))
-

examples/rotate_ellipse.ml

@@ -0,0 +1,15 @@
+open Joy
+
+let max = 32.
+let rec range a b = if a > b then [] else a :: range (a +. 1.) b
+
+let _ =
+  init ();
+  let rect = rectangle 100 50 |> translate 195 220 in
+  let ell = ellipse 100 50 |> translate 60 60 in
+  let nums = range 0. max in
+  let rotated =
+    List.map (fun i -> rotate (int_of_float (i /. max *. 360.0)) ell) nums
+  in
+  show (rect :: rotated);
+  write ~filename:"rotate_ellipse.png" ()