You can choose between two rendering modes:
|PBR||Physically Based Rendering||Painting with metalness/roughness|
|Matcap||Material Capture||Can be useful for pure sculpting|
If you want to learn more about metalness and roughness, see the Paint section.
This manual won't dive into the details about Physically Based Rendering.
One important thing to keep in mind is that lighting and material are fully separated. It means you can paint your object color, roughness and metalness but the lighting should still be "correct" no matter what environment you are using.
As the name suggests, this mode encode both lighting and material capture. If you want to paint your mesh, only the colors will be taken into account, roughness and metalness will be ignored. Also the color will be multiplied against the matcap, meaning if you have a black/grey matcap, using white paint won't make it brighter.
Some artist prefers this mode for sculpting purpose because you can clearly see the shapes and its variations.
You can make your mesh semi-transparent with this slider. Note that because of real-time constraint and depending on the geometry, you can have noticeable visual artefacts in some cases.
If you want to have your mesh fully opaque, make sure to max the slider at 1.0 and not 0.99. Althought it might look similar, there's a lot happening behind.
# Scene Painting
You can check this option if you want to ignore the objects painting. The default paint used is a white non-metallic material, at 25% roughness.