I’ve handpainted weights on this models body which are referencing hair density but is there other way to do it (with modifiers or sth) to make hair automaticly hide under clothes no matter what pose is the bear standing in and not reveal bald patches?
You can try Hair Shape Key which is a paid add-on from grace vfx.
Are you familiar with adding shape keys to keyframe animations?
I think the add-on works in somewhat similar way to keyframing shapekeys.
The above method does not work aumatically. As in Dynamic hair. There is probably some way to accomplish such a goal using hair “Dynamics”. But i’m not the expert.