Constraint object to a vertex on a mesh having a Crate Alembic point cache help needed

[Sylvain Lebeau]

Hi all, 

Totally new here. I come from the sinking boat you all know about.!!!

We decided to jump and try out Maya real soon and so far things are not so bad. 

We just switched our lookdev and rendering dept to maya, animation is still in Softimage for a while. 

I am looking into being able to constraint an object "lets say a light" to a vertex coming from an alembic point cache. It works well if the alembic uses the xform matrix but not on the point cache one.

Anyone eager to help us out with this? ... I've tried Rivet and other tools on Creative crash without much sucess... Same goes for my google try outs...

thanks for your time!

sly

from SHED.

[matt estela]

Hmm... follicle? Or export a null/locator from animation? Alembic supports exporting nulls/locators/transforms, which I found surprising and useful.

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[Sylvain Lebeau]

thanks for this lightspeed fast awnser Matt!... 

yeah, we could manage it with other data exports but the guys at the animation are crumpling under workload on this job and we are trying to leave them as much as breath space as possible. Deadline is comming fast now.

Export times are quite long too. This is why i am looking at a rendering dept solution.

I saw some stuffs about the follicle in my research. Would this allow for an offsetted constraint? I dont necessarly want to constraint object to be at the exact vertex position... It would need to carry out an offset from it. 

sorry...we are a bit noob in maya....we click everywhere in the gui hoping things will just work out! lol

thanks man

sly

from SHED.

[matt estela]

Yep, a follicle just gives you a transform which is parented to a uv position of a mesh, with which you can do whatever you want. You could constrain your objects and maintain offset, or just parent it beneath the follicle transform with whatever child offset you require.

[matt estela]

The question remains of course if a follicle is compatible with an alembic mesh. It should be, and I'd test it for you right now if I could, but ironically I'm sitting in front of C4D right now. :)

[Sylvain Lebeau]

sounds like a good plan!!...

thank you!! will test that tomorrow morning first time!!

sly

from SHED.

[Sylvain Lebeau]

hahaha nice!!!

well i was so excited i remoted my machine in VPN from home.... and you are right, the alembic mesh does not allow me to create nhairs onto it.... bitch!!!

:-)

[matt estela]

Heh, the workstation I'm on has maya on it, couldn't help but have a look...

It works, but there's a few silly things you have to work around.

1. Follicles rely on uv's, my quick test looks like uv's are not exported into the abc file by default. Looks like there's an option there ('uv write'), but if you've already exported, you need to create uv's.

2. So you create uv's with automatic mapping or whatever, but its always downstream of the alembic node, meaning the uv's will swim and update per frame, meaning your follicle will jump around. No good.

3. So you delete non-deformer history, great. Except maya treats the alembic node as a non-deformer too, so it gets removed from the object history. Balls.

4. Fine, get creative. Duplicate the mesh, assign uv's, delete history, then do outMesh -> inMesh from the alembic. No good, outMesh->inMesh sends uvs as well as mesh, so the uv's are wiped as soon as you do the connection.

5. FIINE. Duplicate the mesh, assign uv's, delete history. Duplicate again, Drive that one with the alembic cache. Make the alembic mesh a blendshape target of the uv mesh. Now you have stable uv's, and animation from the cache. The follicle will stay consistent now. Hooray!

If that's not clear I can send a scene.

[Sylvain Lebeau]

ohhh!

you are pretty cool to help me out like this!!!

that sounds very good!!! 

thanks so much Matt... and nice to meet you. And it's pretty clear!.. 

Will keep you updated on my results!

thanks again!!!

XSI list was awesome .... it's amazing to find such help so soon in this forum.

cheers mate

sly

from SHED.

[matt estela]

Heh, thank me if it works. :)

[Cesar Saez]

What about Erick Miller's hyperRealMeshParent script?
It generates a surface between the closest parallel edges on the mesh, so no UVs needed :)

http://terencejacobson.com/hyperRealMeshParent.mel

Cheers!

[Siew Yi Liang]

Hi Sylvain:

hyperRealMeshParent doesn't work on Alembic cached geo in my experience. But one of the rivet scripts I have in my weird collection works OOTB, just tested:

http://pastebin.com/2L7jFy6m

Save as .mel, select two adjacent edges/some vertices and run it. It should create a rivet locator that you can then constrain stuff to.

Hope that helps!

Yours sincerely,
Siew Yi Liang

[Nicolas Combecave]

Hi Sylvain,

Did you try this one:

AnimationMenu > Constraints > PointOnPoly ?

This constraint hasn't the option to maintain offset, so if you need it, just create a locator which you constraint then you can parent anything under this constrained locator, or if you want to keep clean separated hierarchies, parentConstraint something else to this locator with maintain offset on...

Nicolas

[Nicolas Combecave]

Oh, my bad, pointOnPoly constraint seems to rely on uvs as well ! Damn. Looks like it's a repackaged follicle.

[Sylvain Lebeau]

Thanks so much everyone!!

Yi, your Rivet script you gaved me works like a charm!!  I understand that i was not using the same Rivet from another guy. 

it made my day!!

thanks again everyone, and nice to meet you all.

sly

from SHED.

[Milos Vukotic]

I wish I knew of this rivet script few weeks ago :) It's just what I need quite often lately. Thanks for letting us know about it Yi and thanks everyone else cause I really learn a lot thanks to this group.

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[peter shipkov]

Another way is to use the vertexConstraint in SOuP that does this in one step and is much faster than scripted solution. Select one or more vertices and click on the vertexConstraint item. There is only one node that controls them all = fast.