Paint Masks You can paint On the left, a Painted can be used to generate limbs, tentacles, branches, and other. Note: The sections below talk Mask; on the right, the outside the model. All other groups will immediately partially masked to some degree.
By default, masked areas show up as dark patches on the model. Paint Masks You can paint masks on your object directly by holding down the Ctl key while painting on the model. Basically, when in transpose mode, you can Ctrl-drag along the surface of a model, to have a mask dragged out across the surface, following the topology of the model. On models with typical topology, this gives an extremely fast, easy way to mask out limbs, tentacles, branches, and other extrusions. The stroke must begin on the model.