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I made a complicated nodes setup for a material using Cycles. Is there an easy simple way to peek at the data passing through any node, to view it as an image? I desire something like an oscilloscope, where I can touch a probe to any point of the circuit and see what kind of signal is there.

In Blender Internal, I could make many Output nodes and hook them up anywhere, and they'd show the data as a texture on a sphere, cube, Suzanne or whatever. There doesn't seem to be anything like this for Cycles nodes.

Example of using Output to monitor textures along the "circutry". (This is not any sensible texture; just messing around with BI nodes.) Blender BI nodes with Outputs to peek at data

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  • $\begingroup$ maybe you could share an image of one such BI node setup? $\endgroup$ – zeffii Jul 6 '13 at 21:41
  • $\begingroup$ Plug it into the output node? There isn't really a viewer node or anything like that in cycles. $\endgroup$ – CharlesL Jul 6 '13 at 22:25
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Personally, I use a temporary Emission shader and connect it to whatever I want to look at. I also have a small viewport render open almost permanently. The emission shader renders really quickly taking only a couple samples to converge, so it's nearly instantaneous, especially if you go into local view (Numpad /).

I've recently released an add-on that uses this method, but sets it all up for you so you simply have to Ctrl+Shift+Left Click a node to view it's result (just like the compositor).

Emission shader as viewer node

[Update: The Node Wrangler add-on mentioned is included in Blender now, simply enable it in your user preferences]

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  • $\begingroup$ Whether you use an emission or just a diffuse you can input a colour from anywhere in your node setup and send it straight to the material output. One thing we don't have is a shortcut to connect to material output like we do with the composite viewer node. But then material node setups are generally smaller than composite nodes so wiring a node to the output isn't as hard. $\endgroup$ – sambler Jul 25 '13 at 16:06
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    $\begingroup$ I've actually added a feature to the Node Efficiency Tools addon that makes/connects the Emission node using a hotkey, so it acts exactly like the Viewer node in the Compositor. I'm waiting for Bartek to check it out, but you can still download my version of the addon from my comment at the bottom here: projects.blender.org/tracker/… $\endgroup$ – Greg Zaal Jul 29 '13 at 7:09
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    $\begingroup$ Protip: Set that small viewport to local view with the emission shader only (or its own layer, but that pollutes) and it'll eat up less computing power. $\endgroup$ – wchargin Oct 24 '13 at 5:31
  • $\begingroup$ Just to note, you can go into local view by pressing / on the numpad. $\endgroup$ – gandalf3♦ Oct 24 '13 at 17:45
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Use Node Wrangler add-on.

It's delivered with each copy of Blender.

Go to Main Menu > User Preferences > Add-ons > Search "Node" and enable "Node Wrangler" add-on.

Then you can Ctrl+Shift click on any node and it'll be automatically connected in such a way so you can see what is coming out of each the node, and how is it contributing to the material.

I also advise you to read Node Wrangler's documentation, because it does much more cool things that ease up working with nodes:

https://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Nodes/Nodes_Efficiency_Tools

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    $\begingroup$ That's what Greg Zaal said a few years ago ; ) $\endgroup$ – JakeD Aug 22 '16 at 11:33
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There is currently no way to do exactly this is cycles, but you could arrange your screen in such a way as to have a "preview" when you plug your nodes into a Cycles output.

enter image description here

Or also use the preview in Properties Panel > Materials > Preview

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  • $\begingroup$ I use those, but they show only the final material as would be rendered. I want to see the data at various points throughout the node network. $\endgroup$ – DarenW Jul 18 '13 at 6:43
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    $\begingroup$ @DarenW Yes.. unfortunately, AFAIK that's as close as you can get currently. (you can use multiple outputs, but you have to disconnect the other ones to make sure it's actually using the right output..) And you can't see different points at the same time :( $\endgroup$ – gandalf3♦ Jul 18 '13 at 19:36

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