godot substance painter differences

[jaran]

Hello we are troubleshooting differences between substance painter and the godot game engine.  Can anyone from allegorithmic answer the following questions

Is it possible to see Substance's shader code? I wonder if they're using the alpha value from 2012 Burley notes (from section 5.6) rather than 2015 Burley notes (section 3.3). We use the latter for the reasons explained in Heitz paper.

https://github.com/godotengine/godot/issues/18880

[Cyrille Damez]

The code for the parts of the shaders relevant to your issue should be accessible in the doc bundled with Painter, from the Help->Shader Documentation... menu. You can also find the full glsl files for the fragment shader in Substance Designer, in <SD install directory>/resources/view3d/shaders/ (the parts relevant to your problem shoud be in physically_metallic_roughness/fs.glsl and common/pbr_ibl.glsl). The implementation of the BRDF is the same in both products.

We take the linear roughness value directly from the texture, and use "alpha is roughness squared". We never used Burley's 2012 remapping.