[gmpi] Re: 3.11 topic: Inter-parameter linkages
- From: "Jeff McClintock" <jeffmcc@xxxxxxxxxx>
- To: <gmpi@xxxxxxxxxxxxx>
- Date: Wed, 14 Apr 2004 14:18:57 +1200
Hi Tim,
> GUI:
> user twists a knob 1.0
> GUI calls the actor
> actor modifies 1.0 to 0.75
> GUI draws 0.75
> - no (perceivable) latency
The way SynthEdit does it
- Knob gets "mouse moving" message
- GUI calls the actor
- actor modifies 1.0 to 0.75, sets parameter
- Parameter broadcasts to all listeners "update yourself"
- GUI re-draws
- no latency (no visible 'jittering')
So the mouse movement has no direct link to the knob position, redraw is
triggered by the parameter change. This might be completely non-practical
for other windowing systems, But I thought it might be interesting. The
resulting knob code is very minimal, mouse movement and knob drawing are
completely decoupled. The knob dosn't need extra code to ignore
parameter-change broadcasts triggered by itself.
What's really interesting: In the same situation, will a motorised control
surface fight back?
Sorry, digressing a bit.
Jeff
----- Original Message -----
From: "Tim Hockin" <thockin@xxxxxxxxxx>
To: <gmpi@xxxxxxxxxxxxx>
Sent: Wednesday, April 14, 2004 1:46 PM
Subject: [gmpi] Re: 3.11 topic: Inter-parameter linkages
> On Wed, Apr 14, 2004 at 12:42:21PM +1200, Jeff McClintock wrote:
> > > I don't see a clean way to do parameter clipping without making
another
> > > level of dynamism on top of parameters. The ideal would be that the
GUI
> > > knob would just stop rotating at a certain point, until the clip was
> > > resolved. Making it go past the clip then come back after some
latency
> > > DOES suck.
> >
> > That's why the Actor is in the MVC notification loop. No latency. All
> > values are clipped *before* being broadcast to the GUIs.
>
> It works for GUI, but there is physical latency with some UIs:
>
> GUI:
> user twists a knob 1.0
> GUI calls the actor
> actor modifies 1.0 to 0.75
> GUI draws 0.75
> - no (perceivable) latency
>
> Motorized fader:
> user pushed fader to 1.0 (127)
> control-surface interface receives MIDI event (or whatever)
> control-surface interface calls actor
> actor modifies 1.0 to 0.75 (95)
> control-surface interface sends MIDI feedback (or whatever) of 95
> - probably negligible latency?
>
> So maybe it is negligible.. Still recovering from bad flu, brain not 100%
> yet. Trying to not get buried here. I *think* we're really close. What
I
> am looking for now is a way to characterize this into reqs..
>
>
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