You should use the Principled BSDF shader instead of PBR node groups such as Simple PBR. See https://jtheninja.wordpress.com/2017/05/11/substance-and-blender-2-79/ for more information.
Oops, I kept forgetting to post this. Awhile back, I made a note on the old Simple PBR that it had some mistakes in it, and this video by CynicatPro showed a better shader: https://youtu.be/pNiVB7tRG68
I also mentioned I had modified Simple PBR to take these things into account. At some point I mentioned I was going to post it, but kept forgetting to, Well, some people kept commenting to remind me, so, while I watch Bob Ross on Twitch, I’ve packed it up.
Say hello to Simple PBR v4 (no, I never posted v3, it was short lived).
~~~~UPDATE July 18 2016: I’ve modified the roughness calculation for diffuse slightly. This should give less wacky results. Same download link as before ~~~~
Inside there you’ll find 4 node groups:
Simple PBR v4 – Simple PBR, which is sadly becoming a bit less simple internally, but it remains a simple metal/rough shader on the outside. This is the main shader, everything else is modifications of Simple PBR. It should work for metal and opaque dielectric surfaces.
Substance PBR v4 – Simple PBR v4, but with the roughness squared. This will make it play nice with roughness maps generated by Allegorithmic’s substance toolkit.
PBR Fresnel – a group of just the fresnel mask part. This is essentially the same as the group CynicatPro makes in his YouTube video. But it’s there if you need it (such as adding gloss to skin).
Substance Painter PBR v4 – name is a mouthful. Anyway, it’s Substance PBR v4, but with even more mods. It has a channel split and the normal map node integrated directly. It’s designed to be used with a Substance Painter export preset that is included in the bundle. That would be the “Blender Cycles.spexp” file. To install the preset, toss it in your Substance Painter shelf folder. See this doc on where to find that: https://support.allegorithmic.com/documentation/display/SPDOC/Creating+export+presets
Note that these groups will not behave properly with the normal input disconnected. If you are not using a bump or normal map, feed in the default normal from the texture coordinate or geometry nodes (either works).
If you are not using Allegorithmic’s Substance tools, you can stop reading now. The rest of the post deals with integrating these shaders with the Substance twins.
The Substance Painter preset will generate 3 maps:
basecolor (nothing weird here)
“metalRough” – includes roughness in the red channel, and metalness in the green channel. The blue channel is blank.
normalOpenGL – Painter’s OpenGL Normal converted map. This map compiles your height and normal channels together with your baked normal map to create a single final normal map.
You will find corresponding inputs for each of these 3 maps on the Substance Painter PBR v4 node group. Just plug them in, and change the normalOpenGL and metalRough to non-color data (this is important, they will not work correctly as “color”). Don’t worry about adding a normal map node or splitting metalRough’s red and green channels, the node has all of that built in, then passes it to Simple PBR. Just import your textures, set non-color data on metalRough and normalOpenGL, attach them to the group, hook the group to your mat output. Nothing else to it!
Remember that Substance Painter exports PNG files as 16bit, which Cycles will import as float textures. These use more memory, and if you’re rendering on an Nvidia card, you can only have 5 in your scene. Rendering on AMD? Well, you get zero. This has nothing to do with the Simple PBR shaders, just something you should be aware of. You can use a format that is 8bit in Painter, like Targa. Or just live with it.