Ptex general description and questions

[fneill]

Hello, Hate to be a pest but been over a month and Iam still frustrated with no solution. If anybody has had success rendering the ACTUAL .PTEX files from 3D Coat in Maya 2013 Viewport 2.0 (see the previous posts) renderer please let me know. Iam still rendering my Mudbox .ptex sculpts in Maya Viewport 2.0 because can not get 3D Coat .ptex to render. And I sure have tried everything! Thanks much.

[Zeddicus]

It's been a while since I checked this thread and thought I'd share my thoughts. My understanding of ptex is pretty limited, so forgive me if I make mistakes.

The regular bitmaps 3DC exports (TGA, BMP, PNG, etc) do work with the UV's that get set up when importing a mesh for ptex painting, but this isn't really the same as using a ptex file. Seams can be an issue with straight tiled UV mapping during render. Ptex stores not only the image data and mip maps, but information on the orientation and placement of each image tile. The Vray page calls this adjacency data and it's used for applying filtering so that seams are invisible. The adjacency data is mostly made up of vertex numbers I think, which are used to figure out which edges are shared between each polygon and also so each map can be oriented properly on the polygon it belongs to. Each polygon gets it's own texture map and each texture map can have it's own resolution (divisible by 2). You can change this resolution at any time while painting too. People often confuse ptex with the tiling Zbrush does, but as you can see it's really not the same.

So why is ptex nice? You don't have do any UV mapping before painting it (or at least you shouldn't have to anyways). There are sacrifices which come with that of course, such as the ability to work on a texture flattened in 2D like you can with traditional UV mapping (i.e. Photoshop) but I have no doubt someone will come along with a way around that eventually. Mudbox already allows you to transfer your mesh to Photoshop in 3D form with the translation, rotation, and scaling locked, paint on it there, then transfer it back to Mudbox. This is similar to how projection master works in Zbrush (with actually transferring anything to another app of course).

I've been playing around with 4.0 BETA 11, 3ds Max 2013, and Vray 2.30.1 lately and have been having problems too. The support for ptex within Vray has gotten quite good and it will properly render the examples on the Ptex website, as well as anything Mudbox exports. It doesn't want to work with the ones 3D Coat exports though, and I've tried everything. I'm beginning to think that the vertex reordering Max does when you apply modifiers like turbosmooth, meshsmooth, and symmetry also happen when you import a mesh. I've never worked with Maya, but seeing as it's also an Autodesk product there is a possibility that it suffers from the same problems as Max. Since ptex relies on an unchanging vertex order to work properly, the only way importing a mesh and smoothing it is ever going to work is if Autodesk fixes these problems. I have high hopes that since Mental Ray now supports ptex, Autodesk with finally do something about these problems when they go to add the interface elements required for importing ptex files into the material editor. I wouldn't hold my breath though seeing as they are notoriously slow to implement new features, even the ones artists want.

For now the only thing that works remotely the way it's supposed to is by using the scene transfer option in Mudbox 2013, at least with 3ds Max since that's all I an test. You still can't use any of the commonly used modifiers though which is a downer. The only thing I haven't tried, which is basically an idea I got thanks to Vipera's post in this thread, is to create UV's for my mesh in Max, export it to 3D Coat for ptex painting, then apply the ptex file to the UV'd mesh that is still open in Max (not an exported mesh from 3D Coat after ptex painting). I already know this works with Mudbox so hopefully it will with 3D Coat as well.

Edit: The idea I got from Vipera's post didn't work unfortunately. I really don't believe it's 3D Coats fault though, other than it shouldn't alter the UV's that are already on the mesh being imported if their already tiled. One thing I'm uncertain of is whether UV's are needed at all to use ptex. Both 3D Coat and Mudbox will create a set of tiled UV's on any mesh you import, but is this really necessary? I've been assuming it's just an extra step taken by the software so that it can export traditional bitmaps that will work too. Maybe it's a sort of guarantee that if ptex doesn't work, at least you'll still have your paint job. Of course so long as your saving *.mud and *.3b files, that shouldn't ever be a worry as you can always export a bitmap yourself if the ptex file doesn't work in your rendering app. This is especially puzzling if the ptex setup process when importing a mesh into either Mudbox or 3D Coat destroys any UV's it already had. I've never tested to see if that happens. Maybe someone who knows more about it will comment. For now it's all pretty much useless until the various devs of the different apps get it right (100% compatible with no vertex reordering ever).

[Zeddicus]

I finally managed to get ptex files to work and the solution was pretty simple.

The trick was to export my mesh, which had no UV's, out of Max as an OBJ, delete the one in Max, import the one that had just been exported, then load that same OBJ file into 3D Coat. I chose the lowest resolution (the one equal to the total number of polygons my mesh actually has) with all the available options disabled, then painted away until I was content with my overall paint job. Using the Textures menu in the paint room, I exported using the Color to Ptex option (flip ptex quads was enabled), then loaded that ptex file into the material editor in Max (a VRayMtl with VRayPtex in the diffuse slot) which I assigned to my mesh and rendered successfully.

I don't see why this wouldn't work with other apps and renderers if they support ptex properly. The key is to not use any meshes exported from 3D Coat, but instead replace the one in your 3D app with the one you exported for painting. What's great about this solution is that it allows me to keep all my smoothing groups, something 3D Coat still loves to destroy.

If this doesn't work, then it's likely that your vertex order/numbering is being altered at some point during mesh export/import. If not that, then it's possible your doing something to your mesh that is messing up that order, which ptex relies on to work right. As I've said before, in Max this would be caused any number of mesh altering modifiers. Not sure what the equivalent would be in Maya though. You need to make sure you don't make any changes to your geometry after exporting it for painting. This means being absolutely sure you're done modeling and happy with it before doing any ptex painting.

[norbyscook]

Hello 3D coat Community

When using 3D coat, I was somehow able to create a cylinder and start painting material on it with out doing any uv unwrapping... 

All I did was create a cylinder and click on the paint menu button, and I was able to start painting materials on the cylinder!

was I using ptex or did 3D coat auto uv the cylinder I created? 

because in substance Painter an file needs to have UV in order for texturing to work

how come 3D coat allowed me to paint right away? 

it was just a cylinder, I didn't even do any uv unwrapping! 

 

o.O

thank-you! 

[Javis]

It depends on where you created the primitive. If it was created in the Sculpt Room in 3DC, than you were doing vertex painting, which of course, doesn't require a UV map. You can just paint on the vertices if there is no UV map.

[norbyscook]

thankyou Custodian!

that is very interesting!

is 3D coat also good for concept design?

what is the usual work flow for concept art in 3D coat?

 

I recently tried to import a rough sculpt from another program for a test

the OBJ had no UVs

and it seems that 3D coat automatically unwrapped my model

I was able to start painting without doing any manual UV unwrapping. 

I think this is a very fast way to render out my concept modle to paint over later in PS with out having to go through all the stages of UVs , kinda a cheap alternative to key-shot? 

what do you guys think?

:P

thanks!

 

 

 

[norbyscook]

Hello Javis

sorry, I got your name wrong 

 

[Carlosan]

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[Carlosan]