posted 15 October 2006 17:20            

I'm using this expression to smooth the first jump that happens to a pen controller such as !PenX when putting the pen down in a new place:

!PenX smooth: (( 1 - (!PenDown ramp: 0.05 s) rounded * !Smooth * 3) vmax: 0.01) s

I want the initial jump to be smoothed, but shortly thereafter, if the pen remains down, I want !PenX to be accurately tracked (not smoothed). So what I'm attempting to do is start every new !PenDown with an initial large smoothing value and then jump thereafter to a small value (0.01 s).

The expression above mostly works, but it frequently has jumps. In fact, if you paste it into a soundToGlobal controller and compile it, the first !PenDown consistantly causes a jump. Or at least it does for me. I'm having a hard time figuring out where it's breaking down, or coming up with an alternative approach.

I'm sure if I kept at it I could come up with something else, but I'm hoping to learn something if I can figure out why this way isn't working...

posted 16 October 2006 07:10            

I don't have a pen controller but ideas which come to mind would be to have a variable (PenCoord) which holds the current value of !PenX and then testing for the difference between !PenX and PenCoord.

Using the difference you could then smooth by an amount according to a threshold. e.g. If difference > 0.5 then Smooth = 0.05 else Smooth = 0.01

andrew

posted 16 October 2006 19:46            

I do think there is something strange going on between !PenDown and !PenX in terms of !PenX maybe moving a little ahead of !PenDown, but the trackAndHold here doesn't seem to help.

I tried a few variations on Andrew's idea, as best as I could implement it (mostly comparing !PenX with a delayed version of !PenX). I got some things that were close, but didn't find anything that worked any better than what I had.

So far, the best solution I have found is pretty much my original formula, with the ramp time raised a little and minimum smoothing time at 0.05 s - it seems to jump less frequently.

So:

!PenX smooth: ( 1 - (!PenDown ramp: 0.1 s) * !Smooth vmax: 0.05) s

It's not exactly what I was looking for - I want something that tracks absolutely perfectly after an initial smooth fade to the first new value. Here there's still some smoothing because I've set the minimum smoothing time to 0.05 s instead of 0.01 s. Anyway, it's pretty close - it just feels a little sluggish, like there's some resistance to it. Not necessarily a bad thing - at least now it doesn't jump.

thanks,
Phil

posted 18 October 2006 21:36            

!PenX smooth: (( 1 - (!PenDown ramp: 0.05 s) rounded * !Smooth * 3) vmax: 0.01) s

has jumps fairly frequently when I paste it into a global controller. The way I understand it, it should be smoothed every !PenDown. However, increasing the smallest time value (say, from 0.01 s to 0.05 s) that the smoothing happens in seems to eliminate the problem, or mostly eliminate it.

Of course, the cause of the problem may lie elsewhere.