The Power of Just a Few Lines of Code - Why NUKE VFX Artists Need to Understand Scripting and Expressions

Learning to write a few lines of code can have a lasting impact that will help you every time you open NUKE. Saving you valuable time, and lots of it. You don't need to master a scripting language, you just need to know the basics. By learning a few simple commands and how they are made, you can start using expressions and scripting in no time. To begin, let's define each term and how they're used.

What is an expression?

Expressions are small, digestible chunks of code that are easy to remember. You can use these small chunks of code to make minor adjustments to your scene but they have a huge impact to the overall composition. Expressions are used to create relationships between node properties. By using expressions you can make either one node property mirror or offset another node property. You can also use expressions to tell a node property what to do or how to react without using other nodes. For instance you can apply random() to the position property of a node. This expression will set that nodes position based on time and its original position. Wiggle Expression in After Effects wiggle(10,10)

What is a script?

A script contains a series of commands that tells an application to do something. When a script is run, NUKE performs the defined operations and then it is finished. Scripts can be used to automate repetitive tasks such as renaming nodes to more complex tasks, like separating the passes that are contained within an EXR image sequence. Scripts can also do things that you typically wouldn't see in the UI. For instance, you can have NUKE bake expression-driven knob components to key frames. You can have NUKE do this over a certain frame range or view list. You can even create a script to converts a Gizmo  node to a Group node. Now that you have a little better understanding of how an expression or script can be used, you might be wondering how can they help you be a better visual effects artist? Expressions and scripts can save time when it counts and as a visual effects artist, every second counts when you need to meet a deadline.

How should I start?

As a NUKE user, you should spend some time getting familiar with Python. Python is a dynamic programming language that is used in a variety of applications, including Maya. There are tons or resources out there to help you get started in Python  and the Python Software Foundation is a great place to look to stay up-to-date with this evolving programming language. Learning a programming language is no small task, so the best place to start is expressions. Because they are small, digestible chunks of code, expressions are easy to remember and can be quickly integrated into your current workflow. How can scripts and expressions help a VFX artists using NUKE? If you've ever used NUKE, you know how many nodes can be used in a single shot. Using expressions, you can drive multiple nodes and properties using a single node so when a change is made to one attribute it will affect all nodes. 744_MASTER Learning scripts and expressions will also allow you to create Gizmos for NUKE. If you are unfamiliar with gizmos, they are custom tools in NUKE complete with interfaces, logical links and automatic throughput piping. These tools allow you to quickly share workflows with colleagues by combining common tasks. This is useful to all artists and it helps you stay efficient and save time while still getting the best results. You can see how learning scripts and expressions can save you time, but know that you aren't just limited to modifying nodes. More advanced scripts can automate whole systems for speeding up workflows. You can build custom toolsets that you use most often or even modify the existing interface to speed up your workflow. Don't wait any longer or keep wasting your valuable time. Learn more about scripting in NUKE in the Introduction to Python Scripting in NUKE tutorial.