Potential use cases for the script node in Maya

I was so amazed the first time I learned about the script node. Now that I look at it, I feel like it is a necessity, for sure, but back before I had no idea that they, callbacks and scriptJobs existed, I often thought that it would be amazing to have a way of running code at different points of interaction with rigs (and any other maya scene). So when I finally learned about them, naturally, I tried to think of cool things I could do with them as, and today I will have a brief look at some of these alleged cool use cases and some not really cool ones.

Disclaimer: Raffaele over at the Cult of rig has some great videos that go over callbacks, script nodes and a great explanation of how they fit in the overall maya event loop. Once I saw those videos everything started making much more sense, when working with callbacks and script nodes, so I cannot recommend them enough. He goes over the use of script nodes to manage callbacks and I will not be going over that, so definitely have a look at his latest videos.

Additionally, this post will be mostly speculative since a lot of these ideas are just that – ideas that I have not yet tried, but sound like they might be cool.

Also, there are a few examples of unethical behaviour mentioned as potential uses of the script node, so I want to make it clear that I DO NOT encourage them, but instead I want people to be familiar with them, in order to be able to protect themselves.

Table of contents

script nodes in rigging

When I think about script nodes I instantly picture animators opening/referencing scenes and cool stuff happening without them having to touch anything, and yeah, I suppose that is probably the major use case scenario. I wouldn’t imagine myself needing a script node in my files, since I can easily run the code I want to run whenever I want to.

Rigging systems

That being said, though, say we have a rigging system, where we script most of the rig, but we still do certain things in the viewport as well, quite possibly through some cool custom UI we’ve built. That UI will very likely rely on some metadata inside of the scene and probably some message connections between nodes. Wouldn’t it be nice if this UI auto-populates itself and pops up ready to be directly used, without you having to touch anything? Sure, you can probably do that with just pressing a single button after the scene is opened, but I think having it happen automatically feels cooler.

Additionally, I know a lot of people have debug modes of their rigs, which take care of what I am about to say, but if you don’t it might be nice to have a script node remove the restrictions you have added for animators and turn on any diagnostics you have in the scene.

Analytics

Recently, I have been looking into running some minor analytics on rigs and I have to say I see why every marketing person out there praises analytics. It is an eye-opening experience seeing how many unitConversion nodes you have in the scene and maybe plotting that against the performance results you are getting to see if they are slowing you down (they probably are) and by how much (probably not much).

Again, this one is going to be purely speculative, but maybe we can gather some data on our own practices when rigging. Say for example, query the time spent working on a specific rig or maybe even run performance tests on opening or closing the file in debug mode and store that data over time.

script nodes in animation

So, even though, there might be some use cases for script nodes in rigging, I think they can be really useful for automating boring stuff for animators. Whether it is going to be related to building and loading certain UIs, creating certain connections between assets or similarly to the previous paragraph – analytics – we can use the script node to make animator’s and our work slightly easier, more intuitive and informative.

Attaching props

This is probably the best use case of the script node that I know of. I know different places and teams definitely have different approaches to this issue, whether it may be custom tools that are used to bring in and attach props or, god forbid, having all props in a character rig file and using switches to turn them on and off, it is a common aspect of pipelines. I think a nice solution are script nodes. Let’s imagine the following case.

Say we have a character that needs to have all kinds of different weapons, clothes and other wearable props. Let’s suppose all these are their own separate assets, so maintaining them is easier and nicer. The way script nodes would help us in this case is by executing a piece of code that would attach our prop to our character on bringing that prop in a scene where the character exists. That would be a nice and simple solution. Of course, it could lead to some issues, for example, having animators bring the prop in before the character or maybe have multiple instances of the character, so our prop does not know to which it should attach, but generally these issues are either solved or prevented by having some pipeline rules.

Building interfaces

This one is probably more appropriate for freelancers, free rigs and cases where the people working on a project don’t necessarily share a pipeline.

Animators often have to do a lot of animation in a short time. Anything we can do to help them out is going to be great for our production. A nice way we can do that is by giving them easy to use interfaces to speed up their workflow. I know a lot of animators use pickers, so maybe we can use script nodes to build them with all their jazz on the spot. Additionally, they might be like me and love marking menus. Wouldn’t it be great to be able to build it for them on the spot and maybe even show them a message, so they know how to bring it up? Then of course, clean up after ourselves when they close the scene, so we do not mess about with their other work.

script nodes in pipeline

Now even though script nodes can be quite handy for rigging and animation, I think where they really shine is in pipeline. Granted, pipeline would probably use scriptJobs to do most of the things I am going to mention, maybe small teams or even freelancers can sort of simulate a pipeline by using script nodes.

Analytics

I talked about analyzing our behaviour when rigging, but I think it is much more practical to actually analyze the working files of animators and lighters, as the data in there will probably be a bit more interesting. For example, we can run performance tests on certain scenes when opening/closing them and then at the end of a production identify problematic areas, so we can potentially have a look at improving them.

Additionally, this one feels a bit unethical, but if we are upfront about it, it might be cool to store some data on how people interact with our rigs. Create some callbacks on nodes and attributes we are interested in, and have a look at how they are being used. Then when closing the file save that data somewhere we can have a look at it, or in any other way send it to ourselves. We might just find that 50% of the control we are adding to rigs is not actually being utilized.

Licensing

How can we prevent our files from being used by people we do not want to use them? I think “do not let them have our files in the first place” is the reasonable solution, but maybe we cannot entirely prevent that. In cases like that, we can add a level of protection by using script nodes.

Since we can fire a script on opening a scene file, that means that we have some room for licensing our rigs. Now, while I am not entirely sure what the best way for forbidding access to a rig would be, I have a couple of ideas.

Inform us

This first option is not necessarily forbidding anyone from using our rig, but we might be able to setup a way of informing us of unauthorized access to our rig. For example, we can check if the user is unauthorized by looking for a specific environment variable that members of our team would have, looking up maya’s license or maybe even the OS username. If we find that the user should not be using our file we can send the information to ourselves by using a simple HTTP request.

I know this can easily be bypassed, but chances are it might just work in certain cases.

Obviously, this involves an amount of tracking users, which I really DO NOT encourage, but I could imagine certain people in certain cases might want to do that.

Break the rig

If the file is being opened as opposed to referenced we have the ability to break connections, delete files, etc. If that is the case we can easily destroy our rig on opening it, so people cannot even see it.

If it is being referenced though, we do not have that level of control. In cases like this it might be worth having an obscure way of breaking your rig, built into the rig itself. I do not think this could ever be bulletproof, but I think it is certainly possible to make it way too annoying for anyone to mess with it. That being said, it is likely that doing that is going to introduce some overhead in your rigs, so it is not an entirely too graceful way of going about it.

Close or hang maya

I feel like I am getting silly here, but I think that for people that really do not want anyone touching their rigs, they can certainly do a maya.cmds.quit(f=1) in the script node and be done with it. Additionally, if you would like to be extra nasty, I suppose you could do something along the lines of

import maya.cmds as mc

while True:
    mc.warning("All work and no play makes Jack a dull boy!")

Alternatively, if you do not want to be nasty I think the nicest way of denying access would be to just unload or remove the reference, but you would need to have a stable way of finding the reference node. If you cannot do that, you could also do a mc.file(new=1, f=1) to pop out of the scene.

script nodes security

So, escalating from the previous section, I am sure you could imagine that if we could hang and crash maya we probably can do much worse things. Since we are able to run python, even though we have a smaller than the default amount of packages included with maya, we are able to actually execute code entirely unrelated to maya. You know, create/read folders and files, run native OS commands, etc. What if we create and read files from the user’s machine that we really shouldn’t be? Additionally, there are included libraries in Maya that are making it trivial to send data over the internet. You can see where I am going with this.

I do not want to carry on mentioning unethical schemes, but I do want to raise your awareness about the extent to which script nodes can be used. Essentially, everything that is available to the user running maya is available to the script node and therefore to the person that published that file. Which leads us to the next point.

Protection

Now, depending on your OS, the ways that we can protect ourselves from malicious vary, but there are a couple of concepts that we can apply to all of them.

Careful when downloading files

The easiest thing we can do is to not use any files created by other people. Depending on what you are doing in Maya that might be okay, but I for example, very often open popular rigs to see how have they done certain things and how can I improve on top of them.

If you like me do occasionally load up files from the web, there is another check you could do. Open the .ma file with a text editor and check if there are script nodes in there. Since text editors can have a hard time with larger files, you can always write a small python function to check that for you. If the file is a binary file, though, you are out of luck and there is no way to check what is inside of it other than opening it.

Permissions

The obvious one. If the user running maya does not have access to a certain directory, maya doesn’t and hence the script node doesn’t. Please DO NOT run maya as a super user or administrator as that would obviously give maya access to anything.

The practical way of doing it I would say is to create a specific user which is going to run Maya and give it permissions only under a specific directory where you would store all your Maya work. That way, everything else is out of reach.

Firewall

Limit Maya’s access to the internet. That can be a reasonable solution, but Autodesk probably wouldn’t be happy with it, as that way you cannot sign into your Autodesk account.

Conclusion

As you can see script nodes can be really powerful in terms of use cases in a proper production or freelancing and also powerful in malicious ways. I like to believe, though, that people in CG are generally quite intelligent and nice, so therefore I can safely say I am not troubled by the potential exploits.

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