MPE support

[mkruselj]

While we're touching the voice manager, assess what needs to be done to make the synth respond properly to MPE.

[baconpaul]

Both this and #95 and the note expressions one you should also open have two parts

1. Get the value to the voice. This is pretty easy - to the voice structure add a proxy of param mods, the 4 Mpe dimensions, the note expressions etc . this is pretty easy in the clap. Mpe only also doable in the vst3 and au.
2. the consume them in the engine. Especially with Mpe this is hard since you need a way to route the gesture to something. Note expressions other than volume tuning and pan have the same problem

[mkruselj]

Here's the design: DEPRECATED!

MPE button enables MPE (obviously). Gearwheel button next to MPE label changes the whole GLOBAL section to the above design.

Available destinations (8 character shorthands for the display):

OscPitch (both oscs together)
Osc1Ptch
Osc2Ptch
Detune
UniDetun
Osc PW
Osc2 PW
Crossmod
Osc1Vol
Osc2Vol
RingVol
NoiseVol
Cutoff
Reso
LFO1Mod1
LFO1Mod2
LFO2Rate
LFO2Mod1
LFO2Mod2
FiltEnvA (for strike only)
FiltEnvR (for lift only)
AmpEnvA (for strike only)
AmpEnvR (for lift only)

[baconpaul]

Few notes

1. Add O2 detune and probably unison spread to the list
2. This list is also the list for clap polymod
3. I can make a case that the release could be controlled by any factor (harder hit -> longer release type modeling) so I think remove the (for lift only) constraint
4. but those are details. This is exactly the right design.

[mkruselj]

1. But unison detune is not per voice it's kind of a global parameter?
2. Yup.
3. Unsure how much sense it makes for slide or press to affect release time tbh. Also "harder hit" is velocity, which is not a source here?

[mkruselj]

I think we also need a voice level volume target that is just scaling the voice output level at the point of amp envelope. Won't have a dedicated knob on the GUI. This would be a multiplicative target, not additive.

[baconpaul]

1. But unison detune is not per voice it's kind of a global parameter?
2. Yup.
3. Unsure how much sense it makes for slide or press to affect release time tbh. Also "harder hit" is velocity, which is not a source here?

oh velocity should definitely be a source!

every parameter is a global parameter right now. but we know the voice index and can calculate detune so its no different global parameter than any other one.

[baconpaul]

agree on voice level volume target. we will need that for NExp also

[mkruselj]

We don't really have enough room to cram in velocity here...

[mkruselj]

every parameter is a global parameter right now. but we know the voice index and can calculate detune so its no different global parameter than any other one.

Ohhh I get it. Each voice has its own randomized detune offset, and MPE target would simply add in top of the global parameter's value. OK, makes sense.

[baconpaul]

bingo

would be really nice if we can find a way to get vel in. Can we make the buttons 2x2 or something? It is a really commonly used mpe modeling param.