I have a procedural walker, and want to use it as the target of a Suction Force DOP, to have liquid flowing around its body.
From what I have seen, the suction force yields better results, if the target is not moving.

I have seen people use a transform SOP and then an invert transform.
But I don't know how keep the character centered in X and Z, every frame, using the transform SOP.

Using Match Size, I can easily center the character on a per axis basis, every frame, but I don't know how to invert the transformation after, to get it back to its original position.

My bad, this video solved my question:
https://www.youtube.com/watch?v=V1Fz4uNvJr4 [www.youtube.com]

I assume you are not using KineFX as that has its own Locomotion extraction tools, but for any cached deforming geo you can also use extract centroid and transform pieces

cheesetroyer
Using Match Size, I can easily center the character on a per axis basis, every frame, but I don't know how to invert the transformation after, to get it back to its original position.

if you go with Match Size just check Stash Transform at the bottom, that will store transform in detail attrib
as long as you preserve that attrib all the way till th end or copy it back you can then append another Match Size and check Restore Transform to bring it back

tamte
I assume you are not using KineFX as that has its own Locomotion extraction tools, but for any cached deforming geo you can also use extract centroid and transform pieces

Thank you very much, this was very helpful.
I had tried it with the invert transform, but I didn't manage to get it to transform the simulated fluid, in order to match the character's position. With your method, I could simply merge in the fluid before the "transformpieces_to_world".