Dynamically affect a tracer object.

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Old 12 December 2012   #1
Dynamically affect a tracer object.

Are there any good tricks for creating the appearance of a dynamic spline, when it has been created only by a tracer object?

The spline originates or grows from a source, but is too long to simulate in its entirety with good results. What I would like to do, is continue on this path, which looks convincingly like a long piece of string. But unconvincing in that it's a motionless line.
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Old 12 December 2012   #2
A simple cheat without knowing more about the file would be to add a displacer deformer (maybe with falloff) on the tracer with animated noise. This wouldn't create a sense of true dynamics but would give some organic life to the spline.

There may be some other things you can do if you can show a still perhaps of what you want to do.
 
Old 12 December 2012   #3
You can use the tracer for a spline wrap and then apply some dynamics to the result, or you can put the tracer into a mospline in order to apply some effectors tot he result (use a step effector to modify the weight value, and then use a randome ffector set to "noise" type and adjust the weight in it's falloff to make it's effect fall off along the splines length).
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Old 12 December 2012   #4
I considered that (@joel) and could achieve somewhat passable results with this workflow.

Project is a medical device (can't show, sorry) - Sutures coming out and unraveling like floss. The second you have anything coiled, straight up dynamics are pretty much out of the question. Unless you cheat.

I can probably just work two solutions. One a dynamic string that's revealed along a predetermined path generated from the tracers object , the other the actual tracer object with 'from end' limit on the duration.

One for the wish list though - Tracer objects that are initially weighted, but have the potential to become dynamic too.

...edit... Thanks for the additional tips Per.
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Last edited by ThePriest : 12 December 2012 at 01:24 AM.
 
Old 12 December 2012   #5
The solution that worked, as a proof of concept.

#1. Small IK hand rig. Add nulls at each Joint end. Trace zeroed out null points.
#2. Long plane with cloth dynamics. Belt to last null in IK rig.
#3. Select edge points of Plane and record their motion with a matrix object.
#3. Trace result. So that we get a new spline.
#4. Now you have two tracer objects in two individual sweep nurbs.
#5. Remove link to last null from Ik rig tracer object and add it to the Matrix tracer object.

Done.

Download example
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Old 12 December 2012   #6
Remember that you can also use the tracer object to link a set of nulls and form a spline that way. I often do this sort of thing that way, i.e.: setting up a series of nulls defining the path of the thread, and then keyframing the position of the nulls. You could also then (as Per mentioned) use the spline wrap deformer to offset a second, renderable thread along the spline generated by the animated tracer.

Not sure if this is useful or pertinent but came upon this interesting workflow using xReeper (being used for sutures in this example)


https://vimeo.com/55341830

(EDIT--just saw your proof of concept post...)
 
Old 12 December 2012   #7
Yeah, I agree. Perhaps he initial first step shouldn't be an IK rig, it should be a serious of keyed nulls, especially when it comes to the stitches themselves. I do have the flexibility to cut between numerous shots, so I should be fine.


I've tried spline wrap, but to be honest, I'm slightly confused by it.
Do the number of points in the original spline need to match the spline you're deforming?
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Old 12 December 2012   #8
Originally Posted by ThePriest: Yeah, I agree. Perhaps he initial first step shouldn't be an IK rig, it should be a serious of keyed nulls, especially when it comes to the stitches themselves. I do have the flexibility to cut between numerous shots, so I should be fine.


I've tried spline wrap, but to be honest, I'm slightly confused by it.
Do the number of points in the original spline need to match the spline you're deforming?


Not at all. You just need to be sure the deformer & object are oriented along the direction of the target path
 
Old 12 December 2012   #9
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