View Full Version : Suggestions for animating a ribbon

03-19-2013, 01:53 AM
I need to make a long ribbon fly through a bunch of scenes in somewhat specific ways, but am just not getting a result I can either A. control properly or B. get to work well. Basically I've got a long subdivided strip with a slight bend in it across the height, like the curl of a metal tape measure.

Using Inertia gives a good feel, but has 2 problems, one being that it obviously stretches out the ribbon depending on the velocity, the other more problematic one being that it gets dragged around by its origin and makes a point on the ends like >____> which I need to remain flat. A linear weight map across the length works to correct that, but only for the head end -- the tail winds up curved in like )____]

Serpent obviously works as far as controlability goes as it follows the path EXACTLY, which is not ideal (I'd like a little float/play in it like Inertia does) but could be workable... but it's painfully slow; in order to make the ribbon flow nicely I have to subdivide the bejesus out of it, and that kills the speed trying to work with it. I guess I can always rough it in at SubPatch Diaplsy level 0 and then spend the time processing tests at a higher level to make sure there's no kinkiness going on before render.

I've also seen the bone/morph method (morph the flat ribbon moving along its axis and use bones to bend it into shape) but that's a pain the rear to setup dozens and dozens of bones to create my paths through the scenes. I could see how this would be useful for contorting it into very specific shapes though (tying bows and such)

So, just looking if anyone has any other suggestions. Ideally I'd love a result something inbetween Inertia and Serpent :) Some of the 'flowiness' of Inertia but without the tugging, with a little more precision like Serpent.

Is it worth going down the cloth simulation road?

Thanks for any suggestions.

03-19-2013, 07:46 AM
Have you looked at Trailer?

Dpkit also has a shift spline transform node.

03-19-2013, 10:33 AM
Thanks for the references! I forgot to mention I did try Trailer but it was misbehaving, tearing my object to pieces. I got it to work once and it seemed like a much faster version of Serpent, I might have to revisit it and see if I can figure out what I was doing wrong.

Didn't know about DPKit, am looking at it now.. might be the perfect solution though since it looks like I can 'float' the nulls that make up the spline path to give me a some of that flowiness of Inertia, but under complete control. Thanks!

03-19-2013, 10:45 AM
There was a vid (wish I could remember where) about animating a cloth across a bone chain. If it worked for cloth, perhaps it could work for your ribbon? Wish I could link the video but I have no idea where I saw it. But I hope the information gives you an idea where to look.

stiff paper
03-19-2013, 12:16 PM
Mr Rid explains how to do the morph along a bone chain trick in this thread, post #13:
He even throws in an example scene to play with.

03-19-2013, 03:40 PM
Thanks everyone! :thumbsup:

I spent some time this morning playing with Trailer and got a handle on when it goes wrong; It seems to cache the model data in some fashion, such that if you change it in any way (scaling it, or even changing the subdivision level) it will either render slightly goofy or demolish the object completely.. But remove it and add it back or reload the scene and it all sorts out.

Here's an initial test, using a little bit of texture displacement afterwards to give it a little flappiness as well.


Between this and the DPKit spline I think I can get what I need in all these scenes without going too mental ;D