Struggling with multiple materials

[Cain Maven]

So I got a little uppity and decided to try something new: multiple materials that overlap in the UV map. This was partly inspired by Gaia's Kettle Quest, in which the interior of the kettle overlaps with the exterior in the UV map; the point of course is to increase the texture space for the interior.

However, when I try to bake the textures for the two materials both are always rendered, resulting in a fine mess. What I want is to be able to bake the materials individually and save them as separate textures.

I have tried hiding faces and everything else I could think of, but to no avail. I'm sure I'm missing something embarrassingly trivial. Any help would be greatly appreciated!

 

[Chosen Few]

Geneally speaking, if you're baking, you can't have overlapping UV's in the same mesh, even if different faces have different materials on them.  The whole point of baking is to take all the different materials, lighting schemes, etc., that are present on a model, and capture them all in one singular texture. 

To do what you're trying to do, the easiest strategy is to cut your mesh into two or more separate pieces, and then bake each piece as a separate texture.

[Cain Maven]

I was starting to fear that... and I guess it means that Gaia must have baked and saved the texture for the exterior before resizing the interior island so it overlapped.

It would be *really* nice if Blender could let you determine which faces or materials to bake -- or at least ignore transparent materials (which I tried.)

While I do agree that the workflow you suggest will do the trick, it's going to mean quite a bit of extra work, as I was hoping to reuse this element in several places in the build. Oh well.

Thanks for the reply!

[Gaia Clary]

You actually CAN bake different parts of a meshe's UV Map to different target images. I did not use any trick in that tutorial In Blender you not even need to use multiple materials to get this done. The problem is that getting Blender to do it as YOU want is hard. Here is a rough sketch (details are missing)

 

• Enable the Pin tool in the UV Image editor (right to the image selection popup)
• select the part of you mesh that you want to assign to another image in the 3D View
• make sure the uv faces for the selected part are also selected in the UV editor
• Now you can assign a new image to just the selected UV faces.

The main problem is to keep the selections as you have defined them. You can break this association quickly and i must admit that i have not yet found all causes for why the selection can break. Well, this question is on my list of todo's and hopefully a description will show up in my next texturing tutorial.

In the mean time... If someone has a pointer for a good and understandable tutorial on this at hand, would be nice to publish the link here

[Chosen Few]

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Cain Maven wrote:

 

While I do agree that the workflow you suggest will do the trick, it's going to mean quite a bit of extra work, as I was hoping to reuse this element in several places in the build. Oh well.

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You may have slightly misunderstood my suggestion, Cain.  I didn't mean you had to cut up the model, and then leave it in pieces.  I just meant that one very easy way to get the result you want will be to cut it, just for baking purposes. Once the textures have been generated, you can put it back together.

On the (uncut) in-world version, simply apply each texture to its corresponding material face, and you're all set.

 

Alternatively, you CAN do as Gaia suggests, and set up various parts of the singular model to output to different texture bakes.  That's generally a lot more complicated, though, and I have no idea how it's done in Blender.  In most cases, cutting up the model tends to be far less time-consuming, and is a heck of a lot easier to explain.

[Cain Maven]

Well! That did the trick

I was a bit confused at first, because the UV Editor likes to pop back to whichever image it was displaying previously, but once you select the just-baked image again, everything is peachy.

Here are the steps I followed:

• Select the object in 3D view, then hit Tab to enter Edit mode.

• If any faces are selected, hit A to deselect all.

• Select the desired material in the Materials list, then click Select. This selects just the faces with that material.

• Enable the Pin tool in the UV Editor.

• Create a new image for this material.

• Hit Bake.

• Save the image.

• Repeat all steps for the next materials that you want to bake separately.

I'm sure there are snags and gotchas here, but it worked smoothly on the first mesh I tried. I'll post updates if I discover useful tips or tricks (or whine if I can't make it work )

Thank you!

 

[Cain Maven]

Chosen, I did understand what you meant, but for my purposes I suspect Gaia's method will provide the quickest workflow. I can see cases -- involving other meshes -- where I'll prefer your method, though.

In any event, I seem to be back on track, thanks to the two of you. Thanks again

[Gaia Clary]

It is well possible that your roadmap allready enables the full bake modus, that means after you have assigned the images to the materials, go to the render options, and there bake your object. It should also render all assigned images in one single bake task. I set it up in the kettle quest like that, but i worked only on the UV editor and on the 3D View.

 

[Cain Maven]

Ah, maybe that's why it flipped back to the other image. I'll experiment more and see what happens. Thanks