How to build different scenarios in the Compositor

Question

It is my understanding that you use the Compositor for post-production, after rendering the scene. Now I would like to build several "scenarios" for post-production. For instance a node tree that does some color corrections and a node tree that does all kind of fancy stuff with the rendered image. And I want to chose which "scenario" I apply. Is this possible in Blender ? I had the idea to do that with render layers but that does not seem to work. Currently I can only think of building several blend files but that has clearly some disadvantages. How to build different post-production scenarios in Blender ?

I would map all of those processes in parallel branches, and then at the end of each you could mix the results. It wouldn't have to visually mix, as you could use a factor of (0.00 = 100% Branch 1 OR 1.00 = 100% Branch 2), but nothing would stop you from going in between either (which could produce desired visually mixed effects). If you had a third branch take the choice from the 1&2 Mix, and Mix it with 3, then the scenario would be: Choice #1 [choose 1 or 2], Choice #2 [Choose Choice #1 or Branch 3]. You could keep nesting your branches in this way. Sound like what you are after? — Rick Riggs, Commented Mar 2, 2016 at 17:22
Use grouping nodes in node groups. One "scenario", which I think you mean node tree, is grouped in one group, another one - in another and so on. You can mute group or skip it from the final result more easily. — Mr Zak, Commented Mar 2, 2016 at 17:29
@ Mr Zak Can you include different render layers and render passes in those different node groups ? — user13877, Commented Mar 2, 2016 at 17:37
You may want to see this ...... blender.stackexchange.com/questions/47921/… which talks about render layers. — atomicbezierslinger, Commented Mar 2, 2016 at 17:44
As @MrZak I think the solution is Node Groups. You can add render layers in it, but some passes might be disabled until you enable them in the Layer's option. The usual approach is having the Node Group with inputs in which you plug your render layer's outputs. Go and chek about them, you'll see it's what you need ;) — Antonio Buch, Commented Mar 2, 2016 at 18:49

score 2 · Accepted Answer · 2019-05-19 05:33:29Z

2

I see a couple of options:

1 Using a new scene.

Without having to create new files you can use a new scene with linked objects. Changes in the compositor for one scene will not affect the compositor options for other scenes:
2. Using a a Switch and/or Split viewer node

The switch node allows you to re-route the node flow, so you can compare different inputs:

A split viewer node creates a viewer that allows you to compare both inputs simultaneously, by splitting the window horizontally or vertically.