Switch node for bypassing heavy processing
I was hoping the color Mix node would be able to do this but it sadly isn't, even at full Mix settings like 0 and 1 is it still fully processing the disabled side. But it would be nice if there was a node which can be used to completely bypass certain node setups, like heavier postprocessing that is only used in certain moments.
Obviously this is only a concern for animations as stills have just one moment they render but in animations there might be moments where a shot needs some postprocessing and you can't really turn it off after or have it off before to save rendertime on something not actually used anyways.
So I'd like to propose a switch node which has 9 inputs though 5 could work too. The first would be a number input which selects the slot, so 1-8 in case of the 9 input one and 1-4 in case of the 5 input one. This would tell Blender which of the connected slots to process and all others even if connected would be treated as muted and completely ignored.
With this you could add a setup to the compositor for heavy postprocessing and limit this to the range that actually needs it and disable it before and after to speed up rendering without having to break up the rendering for these sections to alter the node setup because there's no animatable way for this.
Ideally there'd be also Switch Value (Number) and Switch Vector version which could also end up being useful but initially a Switch Image node would be sufficient. It also shouldn't be limited to the compositor and instead be added to as many node trees as possible because having this option in a material or a materials texture could still end up being useful.
Alternatively would this be probably easier achievable if the mute setting of the color Mix node would be exposed and animatable because muting a factor 1 Mix node is exactly the kind of switch I'm talking about, well atleast in the way that it ignores the bottom node input chain when muted, it does not ignore the top one while unmuted though but still, closer than anything else.
1 Comment
I think, rather than a switch node like the one you're describing, the problems you're running into could be resolved with some smart optimizations to how the node graph is processed (things like caching, frame muting, and perhaps tree analysis [e.g. branches that never connect to an output don't get processed]).
A variable-input switch node gives some flexibility, but the maximum number of inputs would be an arbitrary choice and such a node has a high chance of being cumbersome in actual use. I think it's a band-aid solution to a deeper lack of optimization.