Help - Control Rig Look / Point at constraints

I imported an FBX from Daz3D that features “look/ point at” constraints.
These basically tell the bones to always be rotated towards a specific target point.
I have uploaded an example video of how it should look, the bones in question are the “neck pistons”.

Of course these constraints no longer exist when importing into Unreal.
I tried to recreate the effect with a Control Rig, but so far I could not find a solution.
Here is a short video that shows the problem:

As you can see, the Debug-Line I draw is the optimal line the bones should follow / be rotated along.

It is actually a simple line from Point A (Blue Bone Control) to Point B (Green?/Yellow? Bone Control color blind sorry)

However, I simply cannot find a way to solve this.

Does anyone here know how I could achieve this? I tried the Aim-Node to make the bones aim at each other, but that just screws everything up.

Hi svenji
Did you manage to resolve this?
I have the same problem, in 3dsmax it’s called “Look at Constrain”.
I also couldn’t figure out what similar command in Control Rig.

Sorry for the late reply I was not active in this forum in forever.

I did actually figure it out.
The best way to handle this in unreal engine is to use physics body constraints.

For my example above I solved it like this:

  1. Attach a physics body to the small piston
  2. Attach a “bigger” physics body to the “tube” it moves into
    I chose 2 rectangular bodies here.

You can then constrain these physics assets. Tell them in which direction to move and lock an axis or two.
You can also set different parameters on how much “wiggle room” each piston has.

Sadly I deleted the project, but if you require more help, I could try to see what I can do.

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Hey, also wanted to jump in and show a setup using Control Rig in case others stumble across this post. I was able to replicate the setup we use in Maya for hydraulics. Mind you the hydraulic joints are one joint chain (pictures and video below)

This is the joint chain, with the following orientations


The control rig setup might look a little confusing, but hopefully, you should be able to make a similar setup for your character.
The rig hierarchy is as follows:


The controls and locators are created from the joints so that they have the same placement. Again, you might have to change the hierarchy to work with your setup.

I start by constraining the joints to these controls. The controls in this case are merely used as a buffer, but you could make the setup the other way around where the joints are parented to the controls. This is just what we needed for our use case.

Next up is the aim-constraint setup. You’ll have to play with the aim and up axis to work with your joints.

The last step is setting up the parent constraint between the different locators/nulls we use and the joints.

Mind you, there are different ways to make a setup for hydraulics, but this is the one we were able to whip up.