Add flying camels example

README.md

@@ -11,6 +11,7 @@ To run these you will need to install Claudius via opam, and then you can `dune
 These examples just show a single feature of Claudius, and are a good place to start if you're trying to understand how Claudius works.
 
 * [Bounce](/bounce/) - example of a bouncing ball made from ellipses.
+* [Flying Camels](/flying_camels/) - example of using image files to recreate a classic screen saver effect.
 * [Polygons](/polygons/) - rotating filled polygons.
 * [Red Hexagon](/red_hexagon/) - a different style of rotating polyons.
 * [Screen saver](/screen_saver/) - a recreation of a classic screen saver effect from the early Macintosh era.

flying_camels/README.md

@@ -0,0 +1 @@
+This example uses the ability to load images as a Picture.t in Claudius to recreate the old [Flying Windows Screensaver](https://microsoft.fandom.com/wiki/Flying_Windows).

flying_camels/bin/dune

@@ -0,0 +1,4 @@
+(executable
+ (public_name flying_camels)
+ (name main)
+ (libraries claudius))

flying_camels/bin/main.ml

@@ -0,0 +1,56 @@
+open Claudius
+
+type point = { x : float; y : float }
+
+let generate_points dimensions =
+  let width, height = dimensions in
+  let f_width, f_height = (float_of_int width, float_of_int height) in
+  Random.init 42;
+  List.init 42 (fun _i ->
+      let x = Random.float f_width -. (f_width /. 2.)
+      and y = Random.float f_height -. (f_height /. 2.) in
+      { x; y })
+
+let move_points t points =
+  let ft = float_of_int t in
+  List.map
+    (fun p ->
+      let distance = Float.sqrt ((p.x *. p.x) +. (p.y *. p.y)) in
+      let angle = Float.atan2 p.y p.x in
+      let new_distance = distance +. ft in
+      let i_dist = int_of_float new_distance in
+      let wrapped_dist = i_dist mod 300 in
+      let f_wrapped_dist = float_of_int wrapped_dist in
+      let f_wrapped_dist = f_wrapped_dist *. f_wrapped_dist /. 100. in
+      let x = f_wrapped_dist *. Float.cos angle
+      and y = f_wrapped_dist *. Float.sin angle in
+      { x; y })
+    points
+
+let tick t s _f _e =
+  let fb = Framebuffer.init (Screen.dimensions s) (fun _ _ -> 0) in
+  let img = (Screen.pictures s).(0) in
+  let w, h = Screen.dimensions s in
+  let img_w = Picture.original_width img
+  and img_h = Picture.original_height img in
+
+  let points = generate_points (Screen.dimensions s) |> move_points t in
+
+  List.iter
+    (fun p ->
+      let x, y = (int_of_float p.x, int_of_float p.y) in
+      let distance_from_origin = Float.sqrt ((p.x *. p.x) +. (p.y *. p.y)) in
+      let scale = distance_from_origin /. 200. in
+      Framebuffer.draw_picture img ~scale
+        (x - (img_w / 2) + (w / 2))
+        (y - (img_h / 2) + (h / 2))
+        fb)
+    points;
+
+  fb
+
+let () =
+  let image_filenames = [ "flying_camels/images/logo48.png" ] in
+  Palette.generate_classic_vga_palette ()
+  |> Screen.create ~image_filenames 640 480 1
+  |> Base.run "Flying camels" None tick