Using "run" To Delay Python Code

This tutorial will teach you how to run Python code in TouchDesigner with a delay. Whether you want to run code at the end of the current frame or wait a certain number of frames or seconds, there is one thing you'll need: the global "run" function. 

The following examples are meant to be pasted into a textDAT. You can then run them (RMB>Run Script or select and ctrl-R) and see the results in a textport.

Attached to this post is a .toe file with all of the examples ready to run.

The Run command

The run command allows you to run a string as a Python statement. It has many a number of options available as to how to run the command. The most powerful feature of these options is to allow you to delay the execution for a certain number of frames or milliseconds. Below is the full wiki documentation for run. This tutorial will go through all the options one by one. 

run(script, arg1, arg2..., endFrame=False, fromOP=None, asParameter=False, group=None, delayFrames=0, delayMilliSeconds=0, delayRef=me)→ Run:

Run the script, returning a Run object which can be used to optionally modify its execution. This is most often used to run a script with a delay, as specified in the delayFrames or delayMilliSeconds arguments.

• script - A string that is the script code to execute.
• arg - (Optional) One or more arguments to be passed into the script when it executes. They are accessible in the script using a tuple named args.
• endFrame - (Keyword, Optional) If True, the execution will be delayed until the end of the current frame.
• fromOP - (Keyword, Optional) Specifies an optional operator from which the execution will be run relative to.
• asParameter - (Keyword, Optional) When fromOP used, run relative to a parameter of fromOP.
• group - (Keyword, Optional) Can be used to specify a string label for the group of Run objects this belongs to. This label can then be used with the td.runs object to modify its execution.
• delayFrames - (Keyword, Optional) The number of frames to wait before executing the script.
• delayMilliSeconds - (Keyword, Optional) The number of milliseconds to wait before executing the script. This value is rounded to the nearest frame.
• delayRef - (Keyword, Optional) Specifies an optional operator from which the delay time is derived. You can use your own independent time component or op.TDResources, a built-in independent time component.

Running a simple script

At its most basic, run allows you to execute a string as a Python script. The following is exactly the same as if you had executed the script argument without wrapping it in the run command.

run('print("hello, world")')

running a script with a delay

 Delaying the script is as simple as adding a delayFrames or delayMilliSeconds argument.

run('print("hello, world")', delayFrames=60)
run('print("hello, moon")', delayMilliSeconds=2000)

including python objects/arguments in the run command

You can include any number of args that will be inserted into the command when it executes. This is useful for inserting variables and running other functions. 

location = 'world'
 
# our first argument is a string, then next is a variable
run('print(args[0] + ", " + args[1])', 'hello', location, delayFrames=60)
 
# running another function using args
def otherFunc(thing):
	print('yo,', thing)
 
run('args[0]("moon")', otherFunc, delayMilliSeconds=2000)

Timing of evaluation of arguments vs script

The arguments passed to the run command are evaluated when the run command is started. Everything in the script itself is evaluated when the run command is executed.

# Note that the first two delayed items use args to print the frame. These are calculated when the delay
# is started. The last two evaluate the frame in the run statement, so they are calculated when the run
# command actually executes.
 
print('Current Frame:', absTime.frame)
run('print("hello, world. Frame:", args[0])', absTime.frame, delayFrames=60)
run('print("hello, moon. Frame:", args[0])', absTime.frame, delayMilliSeconds=2000)
run('print("hello, Venus. Frame:", absTime.frame)', absTime.frame, delayFrames=180)
run('print("hello, Mars. Frame:", absTime.frame)', delayMilliSeconds=4000)

using endframe

The endFrame argument causes the script to be run at the end of the current frame. In the example below, both statements run in the same frame, but the run command happens second because it is deferred to frame end, while the print command happens immediately.

run('print("hello, world. Frame:", absTime.frame)', endFrame=True)
print("hello, moon. Frame:", absTime.frame)

the delayref argument

Using the delayRef argument, you can provide a component whose timeline will be used for the delay instead of the main TouchDesigner timeline. This can be your own independent time component but more commonly you can use op.TDResources which has independent time. Generally, this will be used for a delayed run that will still happen even if the TouchDesigner timeline is paused. If you don't use this argument, TD doesn't consider time to be passing for the delay unless the timeline is playing!

# pause timeline before trying this
run('print("hello, world")', delayFrames=60)
run('print("hello, moon")', delayMilliSeconds=2000, delayRef=op.TDResources)
# unpause timeline after a couple seconds

changing context with fromop

The fromOPargument allows you to run the script as if it is being run from another operator. In general, this will only affect Python that is sensitive to its TouchDesigner network context, such as me and op.

run('debug(me)')
run('debug(me)', fromOP=root)

altering context with asparameter

The asParameter argument affects a legacy run behavior where, when fromOP is specified, op will search inside that operator. That is, if you had torus1 inside geo1, run('print(op("torus1"))', fromOP=op('geo1')) would find the child of geo1, as opposed to searching for a sibling as one might expect. Setting this argument to True (the default is False) would make it search for the sibling instead. This argument is only relevant when fromOP is set to a COMP, and only affects the operation of the op object.

run('print(op("torus1"))', fromOP=op('geo1'))
run('print(op("torus1"))', fromOP=op('geo1'), asParameter=True)

Advanced run command features

The basic usage of run is covered above. This section will detail some more advanced run features including the Run object and the runs collection.

killing run objects

The run command returns a Run object which can be stored in a variable. This is most commonly used to cancel scheduled commands via the object's kill method. 

worldRun = run('print("hello, world")', delayFrames=60)
moonRun = run('print("hello, moon")', delayMilliSeconds=2000)
 
print(worldRun)
worldRun.kill()

the runs collection

All the active Run objects in your project can be accessed via the runs collection.

run('print("hello, world")', delayFrames=60)
run('print("hello, moon")', delayMilliSeconds=2000)
 
print('total runs:', len(runs))
for i,r in enumerate(runs):
	print(i, r.remainingFrames)

killing all run objects

It's fairly simple to kill all active Runs by combining the techniques above... 

run('print("hello, world")', delayFrames=60)
run('print("hello, moon")', delayMilliSeconds=2000)
 
for r in runs:
	r.kill()    
 
run('print("goodbye, world")', delayFrames=60)

Killing select run objects

Killing only select run objects can be more complicated. To facilitate this, you can assign a group string when you create a Run to distinguish the objects from one another. The group is available as a member of the Run. 

run('print("hello, world")', group='world', delayFrames=60)
run('print("hello, moon")', group='moon', delayMilliSeconds=1000)
run('print("hello, Luna")', group='moon', delayMilliSeconds=1000)
run('print("hello, Earth")', group='world', delayMilliSeconds=1000)
 
for r in runs:
	if r.group == 'world':
		r.kill()

testing run object status

Run objects that have already executed will cause an exception if you try to access them. This creates a bit of a tricky scenario if you want to test one that is stored in a variable to see if it is still pending. To get around this conundrum, use a try/except clause testing for tdError.

worldRun = run('print("hello, world")', delayFrames=60)
moonRun = run('print("hello, moon")')
 
try:
	if worldRun.active:
		print('world active')
except tdError:
	print('world inactive')
 
try:
	if moonRun.active:
		print('moon active')
except tdError:
	print('moon inactive')
 
print("\nThis one is okay because it's active ---")
print(worldRun.active)
print("\nThis one errors because it's not ---")
print(moonRun.active)

single update design pattern

One very useful design pattern for run is when you need to do some kind of update operation that can be triggered by many different events, but you only want to do the actual update once per frame. The following example sets this up so that any event(s) can call the scheduleUpdate function multiple times per frame, and the actual update function will only run once at the end of that frame.

# run the "update" function anywhere that requires an end of frame
# update. The update will only run once! 
 
scheduledUpdateRun = None
 
def update():
	# the actual update function
	print('Run updater!')
	scheduledUpdateRun = None
 
def scheduleUpdate():
	# called to indicate an update is needed
	global scheduledUpdateRun
 
	print('Called schedule update!')
	if scheduledUpdateRun is None:
		scheduledUpdateRun = run('args[0]()', update, endFrame=True)
 
scheduleUpdate()
scheduleUpdate()
scheduleUpdate()