How to do delay(), exit() in P5?

kennyLiao

Hi everyone,

in P3, we have delay() and exit(), but didn't find anything similar in p5js reference. What can I do to get the equivalent functions?

Thanks!

GoToLoop

• For exit() there's remove(): http://p5js.org/reference/#/p5/remove
• About delay(), it is wrong to use it after setup()!
• delay() exists to make currentThread() sleep() for a specified time in ms.
• But not for Processing's own "Animation" Thread.
• Rather we use frameRate() within setup() in order to control draw()'s FPS:
  https://Processing.org/reference/frameRate.html
• And that's exactly you should do in p5.js too:
  http://p5js.org/reference/#/p5/frameRate

kennyLiao

@GoToLoop thanks, now I see remove() can replace exit(); but I still wonder what can perform a sleep or pause effect.

for example, I need some function to replace delay() function below in p5js:

    function draw() {

      print("now count down to exit");
      print("3");
      delay(1000);
      print("2");
      delay(1000);
      ....
      remove();
    }

GoToLoop

var countdown = 3;

function setup() {
  background(0);
  frameRate(1); // 1 FPS
}

function draw() {
  countdown || remove();
  print(countdown--);
}

kennyLiao

@GoToLoop thanks, I see what you mean now, but I don't want the whole program to slow down by one frame per second, I only want the 3 second count down to happen before running remove()

GoToLoop

int countdown = 3;

void setup() {
  background(0);
  frameRate(1); // 1 FPS
}

void draw() {
  if (countdown == 0)  exit();
  println(countdown--);
}

kennyLiao

@GoToLoop, also I want help about functions in p5js here as I already know how to do it in processing. Thanks

GoToLoop

http://studio.ProcessingTogether.com/sp/pad/export/ro.9Djm2xo4wna7I

kennyLiao

thanks @GoToLoop, and I googled and it seems that setTimeout() can do the trick

GoToLoop

@kennyLiao, actually for a chronometer, setInterval() is even better than setTimeout(): :P
https://developer.mozilla.org/en-US/docs/Web/API/WindowTimers/setInterval

Both of them allow some function or string to be set apart to run "asynchronously".
It's not a real Thread like in Java though. The closer Java Processing got to it is thread() btW:
https://Processing.org/reference/thread_.html

That PJS online example link shows how to accomplish that via frameCount + frameRate().
A much more common practice is use millis(): https://Processing.org/reference/millis_.html
Both of them would work in any Processing flavor modes like: Python, Ruby, PJS, CoffeeScript, etc. O:-)

blindfish

+1 to using millis. The draw loop is a repeated loop. All you'll achieve with setTimeout/setInterval is creating another separate loop. The only possible advantage is that you can set this to a different rate to the draw loop; but since everything you display is going to be governed by draw you might as well do your time-sensitive events there...

kennyLiao

@GoToLoop and @blindfish, I forgot about millis() and it may just do the trick. I will give a try to setInterval too.