Yes, Substance Painter does its magic with UV maps, and most of the workflow is based on mixing layers with grayscale masks (pretty much what @Michael_W described above), so actual “painting” typically happens to the mask texture most of the time, and not directly to N channels. This way the whole workflow remains non-destructive: amending a grayscale mask is way easier than erasing stuff across roughness+basecolor+height channels.
What makes substance painter special is its “smart masks” (e.g. dirt, soft edges, dirt from ground, etc, etc) which are in fact a simple-ish mix of some of the baked textures (curvature map, world position map, etc). Aaand… to my surprise Blender has excellent support for those as well with Geometry node (e.g. pointiness output which is basically Substance Painter’s curvature map).
And, of course, SP offers a lot of procedural textures, which I miss a lot in Blender. Overall, I find the approach of painting the mask texture fairly acceptable — basically because I don’t actually do too much painting with SP
I personally think there should be a push to have substance/3DC capability in blender. I believe the tech is in there 80%. Not that I think it’s easy to go rest of the way, just think it’s a shame not to reach that goal as well (alongside all the other goals blender’s got lined).
Definitely something that is not gonna be on the list until 2.8 is polished. But some time down the road, maybe in a year or so.
Just feel it’d be a shame not to have a comprehensible PBR texturing tool within blender as well.
Edit:
Shite, didn’t realize this was an old thread.
If anyone is still interested in this concept, I have recently developed an addon called PBR Painter for Blender v2.9+ that lets you do this exact thing, using a layer-based approach.
The addon will be available shortly for purchase.
Would love to see it being used and get feedback to improve future versions.
EDIT: I’ve decided to make some more improvements to the addon prior to release so I’ll link it when ready.
@3DLuver this is quite a old thread but since there has not been any alternative developed in years i made a effort to make the abandoned multilayer paint addon work with 2.9+.
Its quite buggy at the moment but you should be able to paint any layers as long as they are on the brush and the target material.
Also from what i seen while restoring it is that there are many things missing that would require quite a lot of work on the addon to make it intuitive to use and setup. also many things are hardcoded so it uses a fixed set of brush properties which would need to be extended to work with all the brush properties of the painting system.
