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Redo Node Operations in Houdini

So here is something you most likely encounter at some point. We know we can go back and change the parameters of nodes in Houdini. That’s the beauty of its procedural workflow. However, what happens when you’re working with groups or a node that is affecting a certain set of primitives or points and you decide you need to modify the selection? In other words, you want to subtract or add to the group’s set for example. In this #QuickTip we will see how to redo node operations in Houdini.



The Problem

Let’s say you are working on some object creating groups for your primitives along the way. Your network grows more complex then you suddenly see you missed that tiny primitive in you group selections. Ugh! How can you add it into the original Group node? Sure, you can turn on the Primitive Numbers visualization display and add that particular primitive. That’s great if it’s a simple object but we all know most times that isn’t the case. Maybe it’s a handful of primitives in a sea of polygons. Do you just delete the Group node, reselect and drop it back into the network? What if you need to modify the selection on a Poly Extrude?

The Trick

Here is how you can redo the operation on nodes without having to delete and start over. It’s not immediately obvious because it’s a multi-step operation. Let’s do an example on a Group node that feeds into a Poly Extrude SOP.

  1. Select the node you want to modify. In this case, the Group node.
  2. Hit Enter in the Viewport.
  3. Hit the Backquote key (`). The Connection to the Group node will break off
  4. Redo your selection by adding or subtracting.
  5. Hit Enter in the Viewport
  6. Drink some La Croix.


The Redo operation



So let’s go over this again because there are a few important things you need to be aware of. Make sure when you hit Enter and the Backquote key, your mouse cursor is over the Viewport and not in the Network pane. Houdini is context sensitive so this sequence of operations needs to happen in the Viewport. When you first hit Enter you will see the message Accept at the bottom of the Viewport. Then when you tap the Backquote, you will see the connection to the node break off.  You are ready to alter your selection. Here is another example modifying the selection on the Poly Extrude SOP.


Modifying poly selection on Poly Extrude SOP
Modifying poly selection on Poly Extrude SOP


Now that you know that hard way of doing it, check out the easy way in this #QuickTip



I am a motion designer & developer based out of South Florida. When not designing or animating pixels, I wrangle some code. If all else fails, I watch Twilight Zone, I Love Lucy, or Three's Company reruns.