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View Full Version : Sticking objects to a Sweep Nurbs?

PaulT
03-08-2007, 03:32 PM
Hi

I wish to attach some objects to the surface of a sweep nurbs. Think of a rope covered in glue that is being wiggled around. When it hits an object, the object gets stuck to the surface of the rope and gets carried along.

Does anybody know an easy way to achieve this? I'm using c4d9.6 XL (no mograph) Is xpresso the way to go? I know a little bit of xpresso but not much. I have about a dozen objects that need to get glued on so its not a problem to have to turn the constraints on by hand over the course of the animation.

The profile of the sweep nurbs is pretty uniform so it might be possible to fix the objects to the path spline with an offset distance in some way, so they appear on the surface, rather than actually attaching them to the surface itself.

Any help greatly appreciated.
Per-Anders
03-08-2007, 03:54 PM
You could probably do this with Thinking Particles, or xpresso, it depends how freeform you want it.

For example a simple method is to know what objects are going ot get stuck where, and then simply blend their positions using xpresso, i.e. have three nulls, one at point a, one at point b on the spline and achild of that null that's moved out so that it appears on the surface, then you blend between that null and the point a null using xpresso, or any number of contraints tag systems out there.

With TP you'd have to start messing around with proximities, and owrking out how ot find the nearest point on the spline surface to attach to, it wouldn't be so easy (not impossible, just a lot more complex).
vid2k2
03-08-2007, 04:19 PM
how about plug in "place on points" ?
PaulT
03-08-2007, 06:47 PM
I've just figured out an easy way to achieve this. By using align to spline with the object a child of a null to get the offset(So it appears to be on the surface of the sweep not on the spline itself). Then it can be placed anywhere along the spline. Where the desired attachment is to occur, create an instance and alternate the visibility of the free and attached object.

It appears this holds up when the path spline is being animated. The objects don't truely appear to be stuck on the surface but it will probably work well enough in this instance.

So simple it was right in front of me all along!

Thanks for the ideas. :thumbsup:
Srek
03-08-2007, 06:53 PM
Glad you found a solution. An alternative would have been using Hair and TP by letting hair create splines as hair geometry and use the TP Stick to Hair preset.
Cheers
Björn
PaulT
03-08-2007, 07:19 PM
Bjorn,

That would be an interesting solution too. I'm actually using the spline dynamics from hair on the rope, if that is the same thing.
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