Rest Position SOP, explanation?

[talos72]

I know somewhat what a Rest Position SOP supposed to do, but can someone provide an explanation behind this SOP? How does it work?

Thanks

[sibarrick]

Weeellll, not much really. It just adds an attribute to your geometry which stores the current point positions as an attribute called "rest". You could roll your own with an attributecreate but the rest sop pre-dates attributecreate.

The clever bit is how you use it. It can be acesssed inside shaders so that you can add textures to deforming objects without the shader sliding around.

[edward]

Don't quote me on this but I think the rest position is used instead to do the texture map lookup instead of the deformed geometry. So imagine something like putting the texture on the rest geometry first and then deforming it.

[sibarrick]

Don't quote me on this but I think the rest position is used instead to do the texture map lookup instead of the deformed geometry. So imagine something like putting the texture on the rest geometry first and then deforming it.

13865[/snapback]

Yes exactly

[H2O]

Up this topic praticaly 10 years later...   Crazy, nop?   

 

What about relation btw rest position and dops? 

I totally understand utility of this node for texture map but for dynamics...

 

Actually, I've got some problems with fractured object dynamic.

In facts, I apply some transformations on pieces before the dynamic simulation. During the simulation, each piece loses its center of gravity. After a few verifications it's seems like the problem comes from the rest position sop node.

But I don't know why. 

 

Could someone enlight me about this stuff?

 

cheers

[Netvudu]

The good thing about thread-o-mancy is that you see things as mighty e.d.w.a.r.d. on a doubt regarding the rest position

 

I´m not sure about your exact problem on that scene, but to me the rest position just before dynamics makes total sense.

Just imagine you deform your object on DOPs, with cloth, solid or whatever. You obviously want your texture to get the coords before all that fiddling in DOPs so it stays fixed.

 

You might want to post a small example scene with your problem.

Edited February 21, 2014 by Netvudu

[H2O]

Hi Netvudu,

 

Thx for your response. But I think you're misundertanding my question 

 

As I said, I totally understand the link btw rest position and texture coords. And I'm pretty sure that this node had another utility in pre-simulation setup. 

But I don't really know which one...

 

So my question is, which is the utilily of rest position node (except texture coords) in pre-simulation setup? 

 

 

 

Here is a hip file with my problem (in fact, a small example of it  )

For better one understanding, I want to reconstruct the object (so play the simulation reverse) and I have to have the best possible hand on the end of the reconstruction (or the beginning of fracture... follow me? ).

I don't know if this is the better way to do it so don't hesitate if you have a better one.

 

Cheers

CENTER_OF_GRAVITY_ISSUE.hip