Cineversity

I want to animate a fire hose using a sweep object with fixed connectors at each end. I attached the connectors using a PSR constraint, but to make it work, I need the nulls to act like spline handles so I can change the orientation of the connector and have the tracer align to follow suit. But it doesn’t work as expected. Am I just going about this wrong?

Model attached.

Hi mford610,

Thanks a lot for your file.

Please have a look here:
https://www.amazon.com/clouddrive/share/HwL6EK4gR8uUEEKD5Rlz5sfYWip5pWzvoAgeIEtrhyP

Is that the way you wanted it to work? If not, please let me know, I’m happy to look into it. (e.g., Spline IK can have handles)

Cheers, stay safe, stay healthy.

Yes! Holy cow. Is it really that simple? Just by parenting the null to the object, it suddenly gets handle control? That’s nuts. I have to study this out.

Thank YOU!

You’re very welcome, mford610, thanks for the feedback.

What it does is simple. There are four elements in the scene (+the Tracer/Sweep/Circle set up of course). These four elements provide their information to the Tracer. The Child objects are moved by their parents, naturally.
Since you already chose the B-Spline interpolation, the two child objects work more like a rubber-band on the spline. Hence the nice smoothness while being between the Parents in the Tracer list.

So I took your set up and just sorted it.

Enjoy.

My interpretation: Nulls have no dimension, so when they are rotated, there is no displacement. An object has dimension, so when the null is made a child of the object, it “transmits” the displacement info to the tracer. Is that close to what is happening? (I have no idea what I’m talking about)

Why the protection tag? How does that assist?

Hi mford610,

Please have a look at the screen capture:
https://www.amazon.com/clouddrive/share/mwMpPqIrtgVnqFjMA4u6cRGhcrCDHJv92OzkJ5mO1yT

The Tracer is not interested in dimensions, the only information the Tracer uses is the position. If that is an object Axis or a point (Trace Vertices). These positions are then used to trace or connect, based on the Tracer’s settings.
There is nothing more to it, no object-displacement.

Child objects use the parent as their “World” system. If the parent moves, they move; if it rotates, they revolve, or in some cases, rotate. If the parent scales, the child’s world shrinks or expands.

You have used in your example (Initial pos) three Nulls, no object with dimensions at all. It worked to create a Spline. If you moved a Null, the Spline produced by the Tracer changed.

We have four objects in the Tracer; they produce a spline with the vertices/point number 0, 1, 2, and 3.

• The first parent creates point number 0
• The child of this has a distance to the parent and produces point number 1
• The child of the other parent is the third entry in the Tracer list; hence it creates point 2
• Last in the Tracer List is the other parent and its position is making point 3

The Child objects are between the two parents. Since the B_Spline uses the points of the Spline (except start and endpoint) more like a SubDivision Surface. The two points in the middle are pulling on the spline. Hence the soft curvature.

Let me know if this works for you.

ENJOY.

Crazy! That’s just magic.

I will have to study this frame by frame to figure out what you are doing, but it’s exactly the level of control I knew was in there but couldn’t find it. You have brought me to the promised land!

Thank you!

Thanks for the reply, mford610, very much appreciated.

Here is the scene file, rotate or move only the spheres to see the effect:
https://www.amazon.com/clouddrive/share/Jen0xvXyHMJxFkLA0QpxO5ji9yNpWoRkETVL14u4tG9

I have color-coded the scene for clarity; otherwise the colors have no other purpose.

Cheers

Ah! It takes me awhile sometimes. So my understanding is: when arranged as children of the spheres, the nulls - in effect - act as handles for the sphere “endpoints.” I set it up with the nulls not parented and got the same free-spinning endpoints I had before, having no effect on bending the spline direction. But when the nulls are parented to the spheres, they generate the same effect that a handle would. Brilliant!

There are no end to the surprises in this software. Thank you for your patience!

Thanks for the reply, mford610. You’re very welcome.

Let me know if there is anything else, I’m happy to look into it.

My best wishes for your project.