I'm having a problem using the combined (mixed) outputs from multiple mix RGB nodes as an input to the base color of Principled BSDF shader. (Eevee/Cycles alike)

When I route the color output from the final mix RGB node (last in a chain of interconnected mix RGB nodes) directly into Material Output node, I get the expected output in the 3D viewport. However, when I route the same final mix RGB node through Principled BSDF, the object material turns pink.

expected output

This is the desired diffuse output

when routing all of the mix RGB nodes via base color input on Principle BSDF, the material turns pink

material turns pink when routed through multiple mix RGB nodes and then into Principle BSDF

If I make a test connection 2 levels back of mix RGB into the Principled BSDF it works, albeit it's not the complete set of layers I'd like to display along with normals/spec map etc. partial success when connecting from a few mixRGB back, bypassing the larger mixes of ~4 image datas, but only displaying part of what's expected routing from a couple levels of mixRGB back into the base color does work.

partial success when connecting from a few mixRGB back, bypassing the larger mixes of ~4 image datas, but only displaying part of what's expected Annotated full screeny of material setup

Is there maybe a limit on the amount of mix RGB layers or does the data get converted improperly after some level? Is there any way to see what's being passed to perhaps understand what may be going wrong? I've looked around the community boards and it seems in many cases of pink, it's misusage of some node or missing files. I have rechecked the node topology but I don't think I'm passing any incompatible data intentionally, and all of the files are definitely there (there are a total of 10 png format grayscale masks I'm using), I can view them in the image viewer.

One strange item I notice is that on the "last" image texture I added to the material setup, it refused to just name the file the files actual name ("Patch.png") and continues to name it "Image", although bypassing that node completely yields no difference in end result.

  • $\begingroup$ Did you ever figure this out? I'm having the same problem in 2.9 whenever I use a mix shader to combine 2 principled bsdf's. $\endgroup$ – Fractal Jul 29 '20 at 14:16
  • $\begingroup$ Are you using GPU rendering by any chance? IIRC there's a maximum number of textures that can be used with GPU rendering, and things turn pink if you exceed it $\endgroup$ – gandalf3 Jul 29 '20 at 17:21
  • $\begingroup$ The limit referred to in that post was removed entirely for GTX 6xx and higher cards as part of a project for the 2016 Google Summer of Code. Support for earlier cards in Cycles has also been dropped since then, so basically that entire question is obsolete now. $\endgroup$ – JtheNinja Jul 29 '20 at 18:34
  • $\begingroup$ -_- Thanks for the responses. I have to revisit this one, I will try to reproduce it and get back to you all. $\endgroup$ – Sirius A Dec 12 '20 at 21:12

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