Is it possible to communicate back and forth between a plugin and, say, the standard volume faders in Logic?
So a simple example could be a plugin which only contains a single fader. This fader moves when the respective channel's fader is moved in Logic's mix window, and vice-versa, so they are always identical.
Got a feeling this isn't possible, but worth an ask!
I doubt Logic will let you access/control its mix faders in any fashion. What are you trying to achieve? Logic's environment window can sometimes provide ways to do hack-ish stuff.
The only possible hack I can think of would be if your plugin emitted midi control data and you somehow routed that back into the DAW and used it to control the faders.
If I don't need to control the DAW's fader, is there some way to know its current value? Maybe using something similar to juce::AudioProcessor::getPlayHead to get the current play position, etc?
If you're not interested in real-time control you can copy and paste DAW fader automation to the volume automation lane of your plug-in (or vice-versa).
Of course you would have to make sure your plug-in volume curve is a close match to the DAW fader curve (you could use a look-up table, or similar).