Original bug ID: 1970
Reporter: administrator
Status: closed
Resolution: not a bug
Priority: normal
Severity: minor
Category: ~DO NOT USE (was: OCaml general)

Bug description

Full_Name: Christopher Zimmermann
Version: 3.04
OS: GNU/Linux
Submission from: p50842e30.dip0.t-ipconnect.de (80.132.46.48)

This is a wishlist bug.

Hello,

I was just trying to program the game "pong". But the graphics module is just
too slow to do this. Try the following code on a Pentium 166 and you'll see that
it displays only about every second frame:

Graphics.open_graph " 300x225";;
Graphics.set_window_title "Pong";;
Graphics.set_line_width 0;;
Graphics.auto_synchronize false;;

let sleepf x = let y = Unix.gettimeofday () +. x in
while y > Unix.gettimeofday () do () done;;

(let usleep timeout = sleepf timeout;;)
let usleep timeout =
let t1 = Unix.gettimeofday () in
let to_wait = ref timeout in
while !to_wait > 0. do
try ignore (Unix.select [] [] [] !to_wait) ; to_wait := 0.
with Unix.Unix_error (Unix.EINTR, _, _) ->
to_wait := t1 +. timeout -. Unix.gettimeofday ()
done;;

let x = ref 50 and y = ref 51 and mx = ref 1 and my = ref 1
and time = ref (Unix.gettimeofday ()) in
while true do
if !x > 290 && !mx > 0 then mx := 0 - !mx else
if !x < 10 && !mx < 0 then mx := 0 - !mx;
if !y > 215 && !my > 0 then my := 0 - !my else
if !y < 10 && !my < 0 then my := 0 - !my;
x := !x + !mx;
y := !y + !my;
time := !time +. 0.005;
if !time -. Unix.gettimeofday () > 0.
then begin
usleep (!time -. Unix.gettimeofday ());
(* Graphics.clear_graph ();)
Graphics.plot !x !y;
( Graphics.fill_circle !x !y 10;*)
Graphics.synchronize ();
end;
done;;

As you see an usleep function is also missing.

I hope this helps improving OCaml,
Christopher Zimmermann