Exporting/importing Uv Layout To/from A Text File

[cire]

Hi there!

I'm looking for ways to get uv layout information from a polygon model in maya into a text format like xml. Will mel scripting be enough to accomplish this or do i need to do it at the api level? I've had little success with this using getAttr to query the uvst info of the polygon shape nodes. I've managed to get the texture coordinates but not the way they're laid out as you see them in the uv texture editor. Most of the maya options i've explored so far involved the transfer of uv information from one model to another within the same scene.

Another question is applying this uv information from the xml file into a topologically-same model that has only maya's default uv mapping on it. Specifically, how do you guys manually create uv on the faces with only the uv information from a text file at your disposal? This is without using the mapping command. Or will it require the use of those mapping commands?

This will be mainly a pipeline tool for us. I just need anybody here to give me just an idea that will point me in the right direction and i'll take it from there.

Thanks!

Eric

[failure]

UV coordinates are properties of vertices so in order to transfer you need to bring the vertex mapping info along - i.e. something that tells you which uv pair goes to which vertex. This is commonly done by vertex indices. That's why you can successfully transfer only between topologicaly and index-wise same meshes. So if you are exporting - export the vertex index too.

If you want to transfer higher order uv information that maya supports such as uv shells, you'll have to save the uv connectivity info too (which could be abstracted in number of ways).

Most important is: what's the goal your pipeline must accomplish at the end? Maybe there's an easier way than writting/reading xml files.

[cire]

What we want to do is that during asset creation, modeling, rigging,texturing, fursetup and simsetup will all be happening simultanously. And there will be a stage in which different versions of an asset will be assembled using data from those previous stages mentioned. So there will be a version for final render, for sim only, for fur only, for anim, etc. This will then be refernced by the shot stages in the pipe. In texturing, we will be pulling out uv info and shader assignments plus using mayaman generate the renderman equivalent of the asset's maya shading network. I have it working already except for the uv part.

[failure]

Why not simpy transfer it using polyTransfer command?

[cire]

Because as much as possible, I want to get data that i only need from each stage in the pipe. Anyway, I have already figured it out and its not really that hard. The python plugin by Matthias Baas that I'm using is really helpful cause it enables me to integrate mel, maya api, and python in one python script.

[joojaa]

Well in reality its even easier then what you decribe. All you need is to export a rib snipet and cut the uv array form that. Infact if you uuse delight then you can modifly delight just to push the snipet.

Or read it from maya ascii file wich is realy fast to do in python. Infact whuile the python API toolkit from http://cgkit.sourceforge.net/ is way better than the halfhearted earlier approach its still not entirely there yet.

[cire]

Well getting the uv from the rib snippet was the first thing i explored. Problem is i only get UVs and not uv sets. Or maybe i did not really explored it too much. I also looked at getting it from the ascii file. But i had problems parsing maya ascii files cause there is some inconsistencies in the way maya saves scene data to the ascii file.

[failure]

I don't get it. Why all the fuss? Just export the mesh as ma or mb and treat it as your uv data file. It's easy to do import-transfer-delete with simple script. You can write it in about 2 minutes.
And the data overhead for storing the whole mesh is neglectable (unless you have milions of meshes)

[joojaa]

QUOTE(cire @ 07/10/06, 05:01 PM) [snapback]241993[/snapback]
Well getting the uv from the rib snippet was the first thing i explored. Problem is i only get UVs and not uv sets..

You get exactly all thet your rib exporter exports. if its intelligent enough to publish sets it does. If your ultimate goal is rib then this by far makes most sense. Anywwya doing this with API calls is okay even if your api is interpretted by python instead of c++. Its up to you how you balance effect versus effort after all

i tested this on a cube and this is what i got using RAT (i use BOTH rat and delight mainly rat becasue it has some NICE advantages in certain kinds of export customisation areas, altoough delight is flexible in some other areas)

"facevarying float s" [0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 2 2 1 -1 0 0 -1]
"facevarying float t" [0 0 1 1 -1 -1 0 0 -2 -2 -1 -1 -3 -3 -2 -2 0 0 1 1 0 0 1 1]
"facevarying float u_extra" [0.95 0.95 0.95 0.95 0.05 0.0499999 0.95 0.95 0.05 0.0499999 0.0499999 0.05
0.95 0.95 0.0499999 0.05 0.95 0.0499999 0.0499999 0.95 0.05 0.95 0.95 0.05]
"facevarying float v_extra" [0.95 0.05 0.05 0.95 0.95 0.0500001 0.05 0.95 0.95 0.05 0.0500001 0.95
0.95 0.05 0.05 0.95 0.05 0.0500001 0.05 0.05 0.95 0.95 0.95 0.95]

wich is to say the first 2 ones are the default set and the next 2 are the set thats bamed extra- The set itsealf does not catain any more data than this.

The connectivity data is not realy present its one for each face vertex so you dot need to identify the connectivity because its not defined in rib but yes it recreates in maya easily and correctly if you auti sew tham all.

But the nice thing about this is that its easily injected to the rib at any stage.

QUOTE
But i had problems parsing maya ascii files cause there is some inconsistencies in the way maya saves scene data to the ascii file.

And what exactly moght that inconssitency be. There should be none in this case!

Also by the way on the contrary to what people say CORE maya can trabsfeer individual uvesets form a node to another with the maya node polyTweakUV tough its a bit tricky to do. So its easy to transfeer individual sets form obejcts to others.

However had you used the ascii file then all youd need to do is inhject the data into one of theese nodes AS IS.