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Help  Obi Cloth- Character
#1
Exclamación 
Hey,

I had a question about obi cloth. Is it possible to use it on a character and mask out parts of the character like the head/stomach and have the physics applied to that only?

I briefly saw an example of character meshes with cloth applied to them in the demo vid, but did not see anything like that in the tutorials. I saw the ogre vid for obi softbody but I didn't quite see the effect I was looking for.

I considered obi softbody, but I read it can't do certain physics things like self-collision/double-sided that obi-cloth can do which is why I chose the obi cloth instead. 
Correct me if I'm wrong- but it looks like obi softbody is more of a wiggle/jiggle with a "return to original shape". Some kind of radial vertex offset from what I can see.

What I'm trying to achieve is more of a "ripple" like a baseball hitting a round jelly surface and the force ripples throughout the form. The force ripples from the origin and terminates at the outer edges. The shape would always return to the original, but there would be that ripple factor. And you could control the "firmness" or "impact" of the physics on the object.

It seemed like obi-cloth achieved that more closely, since cloth tends to have that ripple effect (from all the physics simulations I've seen involving cloth). Softbody in general seems to be more "firm/bouncy" and almost like a "spring" rather than some kind of "jelly". I could be wrong though, it's just what I've seen/tested so far.
 
To re-iterate what I'm looking for: 
> Has outward ripple effect on impact (from collision of some kind)
> Can control "firmness", "amplitude/offset", "motion multiplier" etc
> Always returns to original form

Any ideas on how to achieve this masked physics effect, and if obi-cloth supports the ripple on characters? 
Or if I should use obi softbody instead- if that more closely resembles what I'm trying to achieve?

Thanks,
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#2
Here's an example of something I'm looking for- whether with obi soft body or obi cloth (I have cloth currently). 

https://www.youtube.com/watch?v=MvZvUW9p2ak

This example is in unity, but you can see the force is distributed in an almost jell like way. The object does appear to return to its original form as well.
I would want some form of springiness control to reduce the amount of recoil or inherited forces acting upon the object. 

And to have the object accept both A) internal inherited velocity B) external collision (such as a ball or square/surface/etc hitting and causing force to distribute against the surface).
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#3
(06-07-2024, 01:25 AM)aallenfx Wrote: Here's an example of something I'm looking for- whether with obi soft body or obi cloth (I have cloth currently). 

https://www.youtube.com/watch?v=MvZvUW9p2ak

This example is in unity, but you can see the force is distributed in an almost jell like way. The object does appear to return to its original form as well.
I would want some form of springiness control to reduce the amount of recoil or inherited forces acting upon the object. 

And to have the object accept both A) internal inherited velocity B) external collision (such as a ball or square/surface/etc hitting and causing force to distribute against the surface).

Hi,

You should use skinned cloth for this. Skinned cloth is just like regular cloth, with the added benefit of skin constraints. These allow the surface of your mesh to be simulated, while giving you control over how much the simulation separates from the rest shape of the object (skin radius) and how much it penetrates the mesh (skin backstop). You also have control over the constraint's compliance (that is, how springy it is).

You can paint all these constraint parameters per-particle in the cloth blueprint editor. This video might help.
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#4
(03-07-2024, 05:40 PM)aallenfx Wrote: I had a question about obi cloth. Is it possible to use it on a character and mask out parts of the character like the head/stomach and have the physics applied to that only?

Yes, just set skin radius to zero for the parts you want masked out. This will force the cloth simulation to follow the animated vertices with no room for extra movement.

(03-07-2024, 05:40 PM)aallenfx Wrote: I briefly saw an example of character meshes with cloth applied to them in the demo vid, but did not see anything like that in the tutorials. I saw the ogre vid for obi softbody but I didn't quite see the effect I was looking for.

which is why I chose the obi cloth instead. 
Correct me if I'm wrong- but it looks like obi softbody is more of a wiggle/jiggle with a "return to original shape". Some kind of radial vertex offset from what I can see.

The main difference between cloth and softbodies is that cloth is a surface, while softbodies are a volume. They have different use cases. For instance, cloth is unable to hold its rest shape unless artificially constrained to a reference shape (which is what skin constraints do) while a softbody can.

In layman terms you could think of cloth as a balloon (just a membrane), and of softbody as a solid rubber ball.

(03-07-2024, 05:40 PM)aallenfx Wrote: I considered obi softbody, but I read it can't do certain physics things like self-collision/double-sided that obi-cloth can do.

Softbodies can do self-collision and double-sided just fine, they're based on the same particle physics framework as cloth.

(03-07-2024, 05:40 PM)aallenfx Wrote: It seemed like obi-cloth achieved that more closely, since cloth tends to have that ripple effect (from all the physics simulations I've seen involving cloth). Softbody in general seems to be more "firm/bouncy" and almost like a "spring" rather than some kind of "jelly".

You could use either cloth or softbodies. However in this case, cloth will give a you a bit more explicit control, since most of the "ripple-like" behavior emerges from skin constraints causing the cloth to spring back to the object's reference rest shape. Tweaking the radius and compliance of the constraints will allow you to control the amplitude and frequency of ripples respectively.

kind regards,
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