Cineversity

I am building a wiring rig using the tracer and control “handles” to create a spline curve effect at the ends (project attached). It works pretty well. The main problem is resizing the length of the tracer. If I shorten or lengthen the tracer, the control points have to be adjusted individually to maintain control of the curve. I suspect there’s an Xpresso node that would maintain the spacing relative to the total length. Or something in Python that says, “maintain 25% spacing between nulls” (or something similarly magical and extraordinarily simple). Do you know?

The second option is using Xpresso to control the points on a spline (see in the same project). This works pretty well also, but I don’t know how to get the vertex handles of the spline to rotate with the assigned nulls/objects. i.e. so that when the pointer rotates, the spline curves with it - same as the tracer option does. I came across a “rotate point” node in X-Tools presets (see Xpresso tag) that might be helpful, but I couldn’t find and info on how to use it in the Help menu. Or am I barking up the wrong tree?

Changing lengths would also be problematic here, too. Once the spline is in Xpresso, the usual scaling options don’t work anymore.

I also saw a demo of using the IK Spline tag to set up the controls, but it doesn’t track with the handles either, at least so far as I could tell. And would it help with changing lengths?

Cinema generally has 12 ways to do any particular operation, so I’m sure there’s something elegant in there hiding in plain sight.

Thanks.

Hi fordmar,

What would shorten the spline? The handles, the defining curve-Nulls? What is the target use of it?

There are no tools that would do that for you by default. The length of the curve is dependent on the Nulls. The nulls would then be dependent on the spline. Sounds like an endless loop. The Spline IK could be set to fit (Equal) the Spline.

Perhaps it is all much simpler and works like the example file.
https://www.amazon.com/clouddrive/share/2tkUYJp0oU5hBg0rRQsmpJ1l3bpqV2ChCr6r9iCNsQW

Could a Pose Morph work? Typically, I assume that we work here for a specific animation sequence and not for an interactive game. This means, what animation do you want to realize?

I could think (brainstorming here) that you measure the distance between the handles (like a direct axis), and from there, you calculate the distance from that axis and its projection to that axis. The shorter the distance between the two handles, the shorter the distance to the axis, etc. /brainstorming end.

All the best

P.S.: Here is a little rig idea. A follow up from the concept I mentioned above.

The project file and a one-minute screen capture.
https://www.amazon.com/clouddrive/share/VxXm21r8ugMKUmDcEGPbfovA8RWYCAK47XjVHnXLTan

Happy Holidays

Yes! That’s it exactly. Though even with the file I can’t say I understand how you did it. I’m studying the Xpresso now. Amazing what can be done when you know how

What does parenting the control points into a hierarchy of nulls accomplish? And what does the little hand icon indicate (it’s green so it’s a Generator of some sort)? The attributes say it’s just a null, but the arrangement and behavior would suggest it’s something more.

I’m not at all familiar with Matrix functions. Going to have to put my thinking cap on.

Hi fordmar,

There are two points Start and End. These two will always “create” a virtual line between them.

This line has a distance. So we have a line and a length. This is the main idea.

On this line, we can place Nulls based on the mixture of the two-point Matrix values. A matrix is not the only position but also includes rotation (as well as scale).

So we place a few nulls there, as you liked to have it 25%, 50%, and 75%, which can be changed, of course.

These Nulls have a child object, exactly on their parent position, and the only duty they have is to receive a scale value. The scale value is based on the distance between the main (start and end) points.
These child Nulls (#S) have a child Nulls (#A) on their own. We move these (#A) away from their parents to create the information we need for the Tracer. In the Tracer, we have five Nulls: start, 1A-3A, and end.

If the start and end get closer together, the distance-value is lower than what is fed into the Range Mapper. This RangeMapper produces a value for the scale of the (#S) Nulls. If that value shrinks, the (#A) Nulls come closer as the scale shrinks.

BTW I have used “Frozen” values on the rig, so you can reset it.

Let me know if there is another question. I’m happy to look into it.

Happy Holidays!

I think I get it. Very clever! I will play around with it and see if I take reverse-engineer the approach. Seems like fun.

So does the hand icon have any meaning? Or is it just a cool label?

Thank you very much, fordmar.

The hand icons are more guidance than anything else. No function.

Enjoy the re-engineering!

Cheers

I take it as a real confidence booster that I could imagine a world where an Xpresso operation could do it. And while I had no idea how, that it could be done was not in doubt. Never underestimate the power of node-based programming!

Yes, exactly, fordmar.

Here, I try to make things easy, but a certain complexity is always included, at least at the beginning.

As my Professor always said, “Chaos is the inability to see the Structure”. So, let me borrow this and say “complexity is the inability to see the underlaying simplicity”.

In Cinema 4D, we always had an option to slap things (objects) together and see what happens. With nodes, we can use now that experience and structure it. As you mentioned, you were able to imagine it. You are spot-on, and I guess you already know more about it than you might be aware of, as you never have “translated” that experience/knowledge into nodes.

It will feel stiff and claustrophobic in the beginning. After a while, you start to structure your ideas already with nodes before opening the app! At that point, you will gain so much more! You might ask what you will gain? I hope that it is something we all will admire and see as something new. Go for it, enjoy the ride.

My best wishes.

I’m a bit overwhelmed by the number of nodes and the somewhat obscure naming convention when it comes to finding which node (or rather which combination of nodes) will do what action. I have reviewed the Help section on Xpresso, and see it all laid out nice and neat (though still obscure). But you really need to know the secret handshake to even begin to untangle the capabilities. Is there a glossary published somewhere with key functions and the job they are meant to do? I have searched through the tutorials for Xpresso fundamentals and get a lot of hits, but nothing systematic pops out that I could find.

We have objects, generators, deformers, and now fields; seems like the Xpresso nodes would be categorized by what kinds of operations they can perform with which components. or maybe I’m just the last one to get the memo.

Hi, fordmar.

Two things are important to understand. Inside of the “wire” runs specific information. From one node connected to the next, that should be a good fit. When you hover over an input or output node, you will see what is needed in the left lower corner of the Xpresso editor.

Secondly, the nodes themselves. But not all nodes are in the list; some are created by just dragging the object from the Object Manager into the editor.

Each node does something little, and the combination of all creates the “magic”. The number of combinations is impossible to cover. It would be like knowing all objects in Cinema 4D and expecting to know how to mix all of those to get any effect thinkable. That will not happen in a short time. The magic is in the combination, and no one has ever combined all objects with all other parts in Cinema 4D.  At least in the last quarter-century using it and 16 years teaching it, I have not seen anyone who did.

What you need to do is to ask yourself, what do you have, and what do you want. Which describes the information given and needed. This, in return, gives an idea of what changes the information need. Besides, information from several sources could be combined.

The beauty of Xpresso is that you do not need to know all, to start using it. The Simplest is the Set Driver/Set Driven option, which is fast and pretty much automatically set while being an Xpresso set up with no doubt.

Another hint, you have parameters in your objects, and they can either be the source of information or the target. A source of information could also be User Data, which allows creating information outside of the objects or the Xpresso Editor. Those User Data options can be combined and work like a mixer.

If you think there could be a connection among objects, think about the source of information, how to change it, and how to plug it into the receiving object. While that doesn’t answer your question above to the fullest (it can’t be answered in a single post here), I can reply to any question you have (please open a new thread then, with an example scene), and I will see if there is an option to solve it with Xpresso.

Allow yourself a little bit of time; you will see it starts after a while to flow. I’m certain you will master it. I’m always a few clicks away and happy to help. Just ask.

Cheers