Baking of multiple high-poly onto multiple low-poly objects using same UV map

Darth_Biomech

Max 2016.
I have my lowpoly and highpoly meshes. It is supposed to be an robotic character, so the mesh is fairly complex, and lots of things are very close to each other and\or intersecting, so I cannot just merge all lowpoly into one object and bake from there.
Since I want to bake AO from the highpoly, I cannot explode the meshes far enough apart to eradicate intersections either, since this will ruin the AO baking (And if I will not explode it just for AO pass, I'll got same issues with intersecting). I could just export both meshes with matching names and bake them in external program (I use substance painter, and it is possible there), but... I also need to project ID's of materials from my hipoly onto my lowpoly, for ease of texturing. So that option is also out of the question.
The closest I got to a solution is to detach everything from the lowpoly that could be intersecting into different meshes, and apply projection modifiers to them with only corresponding hipoly objects included. That should get rid of the issues with intersections... however, this will get me a ton of separate textures in the result bake, several for each object, and I will need to patch them together in Photoshop, and since their paddings will not respect the missing pieces, it will not be a simple copy and paste, and thus a major headache...
So basically, the question is, is there a way to force max to bake multiple objects onto single texture without merging them into one mesh?
Or, if that's impossible, how can I retain ID's of materials on highpoly when exporting it to OBJ?

musashidan

There's a bake by MatID feature that's been in Max for years. Similar to SPainter match by mesh name. Also, why do you say baking a MatID in SPainter is out of the question?

Darth_Biomech

musashidan said:

There's a bake by MatID feature that's been in Max for years. Similar to SPainter match by mesh name. Also, why do you say baking a MatID in SPainter is out of the question?

It is broken for now, if I'm not mistaken, I tried it a while ago, and it outputted just a blank black map. Or maybe I done something incorrectly.
Bake by matID - looks like a solution, but other problem is that some of my lowpoly objects supposed to project more than one material on them.

Butthair

Another option is to explode both of your meshes so there are no intersecting meshes.

For baking in SP, set your ID color source to polygroup/submesh ID, if that one didn't work, then try mesh ID instead.
If your in max, you need a multi-sub material - be sure to also name each sub material so they are unique in name, it might help to give it a color too.

Now... one other caveat, when you export to SP, use FBX or OBJ. If it's FBX, it should export out fine, included the multi-sub material. However, if it's an OBJ, you need to make sure your Export Materials and Create-mat Library options are checked on. SP is going to look at the .mtl file for ID info.

EarthQuake

You can do what you're looking for with Toolbag 3 - use bake groups to prevent intersecting, use name matching to automatically set up the bake groups, and use the "ignore groups" AO option which will give you AO between the various HP groups. Toolbag can bake a material ID mask too. So unless you need to bake out complex shaders or something like that from Max, I think this should work for you.

More info here: https://www.marmoset.co/posts/toolbag-baking-tutorial/

Darth_Biomech

Thanks!