Soulburn Studios Art Lessons

Ptex Use In Mudbox 2013
By Neil Blevins
Created On: Apr 14th 2012
Updated On: Apr 18th 2012

Go here to read this tutorial in Russian.

First, please read the more general Ptex tutorial to learn about the Ptex format. Once you've done so, this tutorial discusses using Ptex with mudbox. Mudbox 2012 had Ptex support, but full Ptex support comes with mudbox 2013, so this tutorial assumes you're using mudbox 2013.

To paint using Ptex, you first need a 3d application, a renderer and a 3d paint program that all support Ptex.

3d software like 3dsmax using Mankua's Stripes plugin will allow you to assign Ptex files to your objects.
Prman and Mentalray 3.10 standalone will render Ptex files. Vray also reads Ptex files.
3d Paint apps like Mudbox and Mari support Ptex.

Eventually, you'll probably see all 3d software being Ptex compatible, but until then, do a little research to make sure you can use Ptex in your personal pipeline.

Setup Ptex In Mudbox

To paint on your model using Ptex, you need to follow these steps...

Select your mesh in mudbox
Go to Mesh -> Ptex Setup. This will let you increase or decrease the size of your Ptex files on the mesh (more texels means more resolution). Watch the preview on your mesh, and increase or decrease the size of your Ptex file until the pattern on your mesh is no longer blocky.

If you ever need to upres or downres your Ptex painting, just go back into Mesh -> Ptex Setup, it will remember your current setting, and let you modify the resolution. Remember, the more resolution, the larger your Ptex file and the more RAM it takes up.

Adding More Resolution On A Per Face Basis

If you want to increase the resolution of just a part of your Ptex file (like add a larger Ptex to just the forehead of a face)...

Go to Windows -> Preferences -> Render -> Render Selected By Face.

Go to the "Select/Move Tools" tab, choose "Faces", then paint a selection of faces on your mesh.

Now go back into Mesh -> Ptex Setup, and increase or decrease the resolution. These changes will only affect the selected area of your mesh.

Saving A Ptex file With Your Mudbox Scene

There are two ways to save out your paint as a Ptex file. First, you can select a paint layer in the Paint Layer menu, right click and choose "Export Selected". The second way will save a Ptex file when you save your mudbox file (which is what I recommend). To do this, go to Windows -> preferences -> Files -> Save Ptex Textures with .mud file.

Now when you choose "Save" to save your .mud file, it will also save the Ptex files in your scene. The only disadvantage of this technique is file saving will now be slower, since it's saving your scene's Ptex files every time you save your .mud file. If you don't want the speed hit, then feel free to use the standard "Export Selected" feature.

Ptex Works With Ngons in Mudbox 2013

New to mudbox 2013 is ngon support. In 2012, you could only paint to Ptex on meshes where all of its faces were 4 sided. Now you can paint on a mesh that contains tris, 5 sided faces, whatever.

Baking Your Ptex to UVs

One of the major advantages of Ptex is you don't need to set up UVS on your mesh. But what happens if for some reason you suddenly need a UV version of your paint? Like maybe someone needs your mesh for a game engine, and their game engine doesn't support Ptex. You can bake your Ptex into standard bitmaps using UVs. Here's the workflow...

1) Load your original mesh which has Ptex assigned and has some paint.
2) Load your new mesh that has UVs.
3) Go to Maps -> Extract Texture Map -> New Operation
4) Choose "Transfer Paint Layers", the Target mesh is your uv mesh, and the Source is your Ptex mesh.

5) Transfer, and now your Ptex paint has been baked to regular tif files you can assign using the uvs on your new mesh.

Baking Your Ptex To A New Model With Modified Faces

Lets say you take your mesh (say, for example, a human head) and paint on it using Ptex. Then you have to make changes to your mesh, like maybe adding some spikes to the forehead by extruding a face, and then adding an extra span to the mesh. You can't just assign your Ptex file to your new mesh, since the Ptex file is expecting a different mesh with a different face count. But repainting the face would be time consuming. So you need to bake the paint from the original Ptex mesh to the new mesh. You do this in a similar fashion to baking to UVs.

1) Load your original mesh which has Ptex assigned and has some paint.
2) Load your new modified mesh.
3) Go to Maps -> Extract Texture Map -> New Operation
4) Choose "Transfer Paint Layers", the Target mesh is your new modified mesh, and the Source is your original mesh.
5) Transfer
6) Touch up any problems, like for example, since the original mesh didn't have spikes coming out of its forehead, you'll need to paint the spike with new paint. But parts of your mesh that didn't change much should transfer over with a minimum of texture loss.

Baking Your Displacement To Ptex

If you've used mudbox to sculpt, you're used to extracting displacement maps out of the software. See Converting A Mudbox Model To 3DSMax as an example. Well, you can now bake your displacement map to a Ptex file instead of a usual tif. This means you can bake a displacement map without the need for your object to have UVs. To do so, just bake like you normally would with Maps -> Extract Texture Map -> New Operation -> Displacement Map or Vector Displacement map, but instead of choosing a 2d format like tif for your output file, choose Ptex.

Transferring Ptex Files

You can also now easily move Ptex files between applications, so say you want to start painting your Ptex file in Mari, but then want to move it over to Mudbox to do your final painting because Mudbox has some features you want to use...

Import your Ptex file directly into mudbox by going to File -> Import (this will load the mesh and the paint inside the Ptex file)
Or, say you have your mesh open in mudbox, and it already has a few layers of paint, and you want to import a new paint layer from a Ptex file, just select your object, go to your paint tab, and choose "Import Layer".
Or, say you have a Ptex paint layer in mudbox that you want to transfer to Mari, just select the paint layer in the Paint Tab, right click and choose "Export Selected" and save it as a Ptex file.

Using Ptex files in your 3d App

Once you've created a Ptex file inside mudbox, you can use it in a number of 3d apps and renderers.

And here's some info for people who are interested in using ptex files in mentalray for Maya.

Here's a tutorial on how to export displacement and color from mudbox and render it using Vray for 3dsmax.

Conclusion

So that's just a few of the things you can do with Ptex files in mudbox 2013. Hopefully that gives you some practical examples of how to use Ptex files in mudbox, and the sorts of manipulations you can perform on them.