Cineversity

What’s the most efficient way to animate a flexible hose that’s attached to different objects on each end?  Using a Tracer object and nulls to define a spline path for a Spline Wrap deformer works for the most part, but I’m wondering if there’s a way to constrain the length of the spline to the length of my hose model.

Let’s say I have a vacuum cleaner with a 1 meter hose.  One end is attached to the base of the unit, the other to an attachment.  Using a group of nulls, some parented to the base and some parented to the attachment, with a few more for control, I can assign those to a tracer object to create a spline for a Spline Warp for my hose.  The problem is, if I pull my attachment object more than 1 meter from the base of the unit, my hose will “detach” from the vacuum cleaner.  Because I don’t want my hose to stretch I have “Keep Length” selected in the Spline Wrap.

Is there any way to make it so my spline is always 1 meter long, even if the spline is in an “S” shape or something?  Or is there a better way to do this?

Thanks.

Shawn Marshall
Marshall Arts Motion Graphics

Hi Shawn,

There are several options. But let me start with the simplest one. I have attached a file with the name XPsl (XPresso Spline Length). It let you animate freely with no “mechanical” constrains, but the length of the spline is always visible in the Object Manager. So the animation is as you did it already, but you can control the length. You might think that you have to memorize this number always. No really, you could just subtract the target length from the result and get in that way always a positive or negative number. This will indicate “too long” or “too short”.

When I use the term mechanic, I think of the conditions, manageable on both ends, keeping the length and behave like a hose. If you can do it manually in time, perhaps you enjoy the control.

In the zip file is a second option based on a spline. I use here a character tool to limit the length. But it is not as simple to animate as the Null—Tracer combination. You might include the “Handles”, of course you might think different than I do.

I could as well think about a Dynamic solution with “Connectors” and perhaps Gravity, and many little things to get it where you want to be. But if keeping the length is your main problem, stick with the way you do it so far, and keep an eye on the number. Normally a small change in length might not be visible at all, just saying to save some time. Which I would always consider, the time for the set up, and the time to animate. Both need to be seen and to be summarized on the end of the day.

Let me know if that helps already or if you like to dig deeper.

When Dynamics (2) hit the package, creating a chain was certainly on top of the list, which could be thought of a “back-bone” for the Hose.

https://www.amazon.com/clouddrive/share?s=8Z1fjNhERVkrhJia3z92W8

All the best

Sassi

Hi:

Thanks for the reply; sorry I didn’t respond sooner, but I was on deadline for this.  I ended up using the method that displays the length of the spline.  That made it easier to keep the length close to what it was supposed to be, and then just fit the hose model to the spline.  The slight compression and expansion that occurred was acceptable.

Cheers.

Shawn

You’re welcome, Shawn!

I’m glad the simplest version was kind of useful. Close to a deadline doesn’t sound like a huge pleasure in terms of long “Research&Development;”. ;o)

I hope your project is well received!
My best wishes

Sassi