How to execute a Maya MEL procedure at regular int

Question

I would like one of my Maya MEL procedures to be executed every x seconds. Is there any way to do that ?

Answer 1

In general, no. However in Python I was able to create something that works pretty well:

import time

def createTimer(seconds, function, *args, **kwargs):
    def isItTime():
        now = time.time()
        if now - isItTime.then > seconds:
            isItTime.then = now            # swap the order of these two lines ...
            function(*args, **kwargs)      # ... to wait before restarting timer

    isItTime.then = time.time() # set this to zero if you want it to fire once immediately

    cmds.scriptJob(event=("idle", isItTime))

def timed_function():
    print "Hello Laurent Crivello"

createTimer(3, timed_function) # any additional arguments are passed to the function every x seconds

I don't know what the overhead is, but it only runs on idle anyway, so it's probably not a big deal.

Most of this can be done in Mel (but as usual not as elegantly...). The biggest roadblock is getting the time. In Mel you'd have to parse a system time call.

Edit: Keeping this Python, you can then call your Mel code from within the python timed_function()

Answer 2

The mel setup would be

scriptJob -e "idle" "yourScriptHere()";

However it's hard to get the time in seconds from Mel - system("time /t") will get you time to the minute but not to the second on windows. In Unix system("date +\"%H:%M:%S\"") would get you hours, minutes and seconds.

The main drawback to scriptJob here is that idle events won't be processed when the user or a script is operating - if either the GUI or a script does something long you won't get any events fired during that period.

You can do this in Python with threads as well:

import threading
import time
import maya.utils as utils

def example(interval, ):
    global run_timer = True
    def your_function_goes_here():
        print "hello"

    while run_timer: 
        time.sleep(interval)
        utils.executeDeferred(your_function_goes_here)
        # always use executeDeferred or evalDeferredInMainThreadWithResult if you're running a thread in Maya!

t = threading.Thread(None, target = example, args = (1,) )
t.start()

Threads are much more powerful and flexible - and a big pain the the butt. They also suffer from the same limitation of as the scriptJob idle event; if Maya's busy they won't fire.