Forums > Jitter

leaving trails


May 15, 2008 | 2:21 am

I’m drawing moving dots in jit.lcd, as part of a motion tracking patch. I want the dots to leave trails that fade away slowly over time. If I use jit.slide then I can’t get the trails to stay for long enough.

Any suggestions?

Or should I be using jit.gl.sketch anyway?

May 15, 2008 | 2:47 am

no need for sketch, convert your lcd to float32 matrix before going to
slide, it will stay longer.
thre are other methods, search for "trail" "feedback" "jit.slide"

On Thu, May 15, 2008 at 5:21 AM, Ed Purver wrote:

>
> I’m drawing moving dots in jit.lcd, as part of a motion tracking patch. I
> want the dots to leave trails that fade away slowly over time. If I use
> jit.slide then I can’t get the trails to stay for long enough.
>
> Any suggestions?
>
> Or should I be using jit.gl.sketch anyway?
>

June 5, 2008 | 5:55 am

you can take a matrix feed into jit.xfade, take the output into speedlim 50 (50 ms = smooth fades), then that goes back into the right inlet of jit.xfade. So it crossfades with itself, sending a frame every (50 ms. or whatever) to the other inlet, thus giving feedback of sorts. You also need one of the jit.xfade outputs to go to your pwindow to see it. :)

With the xfade at 0.0 it’s clean regular video, at 1.0 it appears to stop (because all signal is the feedback and it stays on that image), and at about 0.85 you’re in dreamland. I use it all the time and it’s great for getting that smeared, trails, dreamy effect with a single video or camera capture. Change the ms in speedlim for longer waits between "sampling" the current frame to feed back… maybe synch this with an audio bpm source?

speedlim is needed as you can’t directly hook the output of jit.xfade into outlet 2.

I’d post an example but away from Max right now. Trust me, it’s simple and really adds to the possibilities—plus it helps smooth out any choppy cuts in video.

–CJ

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Forums > Jitter