Hmmmm...I built one like this once...I think.
I don't recall exactly what I did but I think this would work (better):
First things first, decide what controls it. If it's MIDI you're looking at 0-127 control values, better off with Audio control. You can make a 128 point table that uses the curve you like, then read it from [tabread4~] with a MIDI CC or a [line~] for (much) higher resolution.
Anyhoo, it sounds like you'll want to take advantage of [moses] to separate the the control values into different ranges. Here's a thought:
0-24: controls LPF
24-48: controls LPF & BPF & and a crossfade curve between them
48-72: controls BPF
72-96: controls BPF & HPF and a crossfade curve between them
96-127: controls HPF
And now someone will say "but the phase distortion..." Yeah, I'm not phased.
When we say morphing there are much more complex ways of accomplishing this effect than crossfading - but crossfading is simple.
For visualizing it - well, you know what it does so it's an unnecessary burden on your CPU, but if you don't care about latency you can explore data structures - it'd be difficult to construct. Other alternatives are silly, like using noise and an FFT plot - but you'd be able to do that by hacking apart the resynthesis sample I think, again only if you are using it for production.
Please share, I could use a well thought out filter of this type - it's common in the old Traktor, right?
-J.P.
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