add basic movements

src/island_client.ml

@@ -1,3 +1,5 @@
+let () = Random.self_init ()
+
 module Map = struct
   type background =
     | Grass
@@ -8,12 +10,12 @@ module Map = struct
 
   let height = 1000
 
-  let player_pos = ref (500, 500)
+  let player_pos = ref (20, 3)
 
   let m =
     Array.init width (fun _x ->
         Array.init height (fun _y ->
-            if Random.int 1000 = 42 then Water else Grass ) )
+            if Random.int 1000 <= 42 then Water else Grass ) )
 
   let get_tile_kind ~x ~y = try m.(x).(y) with Invalid_argument _ -> Black
 end
@@ -82,10 +84,7 @@ let draw_map () =
   done;
   let (_ : Jv.t) =
     Jv.call context "drawImage"
-      [| papy_bottom
-       ; Jv.of_int ((width / 2) - (tile_size / 2))
-       ; Jv.of_int ((height / 2) - (tile_size / 2))
-      |]
+      [| papy_bottom; Jv.of_int (width / 2); Jv.of_int (height / 2) |]
   in
   ()
 
@@ -96,6 +95,34 @@ let () =
   in
   ()
 
+let kb_handler e =
+  let x, y = !Map.player_pos in
+  let x, y =
+    match Jv.to_string @@ Jv.get e "key" with
+    | "z" -> (x, y - 1)
+    | "q" -> (x - 1, y)
+    | "s" -> (x, y + 1)
+    | "d" -> (x + 1, y)
+    | _s -> (x, y)
+  in
+  let x = max 0 x in
+  let x = min (Map.width - 1) x in
+  let y = max 0 y in
+  let y = min (Map.height - 1) y in
+  Map.player_pos := (x, y);
+  draw_map ()
+
+let bind_keys () =
+  Jv.call window "addEventListener"
+    [| Jv.of_string "keydown"; Jv.repr kb_handler |]
+
+let () =
+  let (_ : Jv.t) =
+    Jv.call window "addEventListener"
+      [| Jv.of_string "load"; Jv.repr bind_keys |]
+  in
+  ()
+
 (*
   let draw_background () =
     for x = 0 to tiles_per_w - 1 do