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 while the lighting is handled independently. It allows you to paint your object and then tweak the lighting later, without breaking the overall look of your model.
As the name suggests (MATerial CAPture), a matcap takes care of both the lighting and material information in a single image. Since the material itself is already present in the matcap, roughness and metalness painting channel will be ignored. The painting color will be multiplied against the matcap, meaning if you have a black/grey matcap, using white paint won't make it brighter.
Artists tends to favor this mode for sculpting purposes since they allow to focus on the shape and geometry itself.
This mode will is simply using the matcap as a base color for PBR. It's possible that this option might be removed in the future.
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.