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Motion trails that DON'T EVER fade from live feed (Jitter)

November 3, 2013 | 4:22 pm

Hello!

I’m currently working on a project where I’m using Max/Jitter and a Kinect camera (although I’m not using the depth-perception aspect typically associated with the Kinect).

To briefly describe the project, it basically consists of the Kinect camera mounted on the ceiling that "tracks" people through the space by leaving a motion trail behind the viewer. This live feed, including the motion trail, will be visible to others on a monitor screen from OUTSIDE of the space.
There will also be an object directly centered in the camera’s view (and the space in which the viewer walks). **When people step into the center, the motion trails will be ERASED, and the people viewing the monitor will witness the space as trail-free for a moment until the person in the space starts moving again. (The patch also saves the last frame before the motion trails are reset to the computer, which forms a photographic archive of all the trails that are made.)

So, I’ve been able to figure all of this out– aside from one aspect.
*I want the trails to NOT FADE at all (until they are cleared by someone stepping in the center of the frame).
I’m using jit.change and jit.slide to achieve the current motion trail that I have in place. I have made the jit.slide last for a while, and turned that function all the way up, using the silde_down attribute. I’ve set the scale factor for slide_down as 1000000 although I’m pretty sure numbers higher than 100,000 don’t make the trail last any longer.

SO, my question is:
Is there an object, other than jit.slide, that can have the same effect, but where the trails don’t fade (until I reset them with the "clear" msg)? Or, is there a different message/attribute I can sent to the jit.slide object?
If no object does this, I was also thinking that maybe there would be a way to unpack and perform operations on numbers involved with the jit.slide function so I could "slow down" the fade a LOT, so that (if each motion took 10 sec total to fade now) I could make it take, say, 60 seconds or 1000 seconds to fade.

This is for a class project with an upcoming due date, so any help will be MUCH, MUCH appreciated!!

The patch is below:
<code>

– Pasted Max Patch, click to expand. –

</code>


November 4, 2013 | 8:43 am

Render your scene in the GL world and set jit.gl.render’s @erase_color to 0. 0. 0. 0.

No time to make the patch for you, but see jit.gl.render and jit.gl.videoplane


November 8, 2013 | 10:36 pm

Thanks so much! I was completely unfamiliar with GL but ended up using jit.gl.slab and jit.gl.texture (tp.slide.jxs-help.maxpat in the examples folder).


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