Nuke Python Expression Switch

Nuke’s Python expression syntax can be shorter and more readable than tcl.

Imagine, you want to use a switch to toggle part of your comp on or off on certain frames – maybe to fix artifacts in a 3D pass. Instead of animating a switch’s input or a tool’s mix slider between 0 and 1 you could use an expression:

frame == 1025

This will set the knob to 1 on frame 1025 and to 0 anywhere else. An expression like that also works if you want to enable that knob on several frames, but it gets increasingly unreadable:

frame == 1025 || frame == 1072 || frame == 1074

A Python expression is shorter and easier to extend. Enable the Py button in the expression popup and there you go:

nuke.frame() in [1025,1072,1074]

Tags: Nuke, tutorial

This entry was posted on Saturday, January 11th, 2014 at 11:59 by Stefan and is filed under English, VFX. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.