Konstantin wrote:
Gimp has layer groups and group layer masks, but no clipping masks.
What sallyanne linked to is a workaround but no real clipping mask.
What any of this has to do with shading and colour rotation is beyond me.
You can do shading/highlighting on a seperate layer and colour rotation is just a technique to pick colours.
What exactly does this clipping group do in Medibang Paint??
According to their website, "The clipping function references the layer below and makes it possible to color or draw only on the marked sections of that layer."
Essentially, it works in a layer group, and prevents the layer on top to be going outside of the layer below.