This uses the values form the stroke automasking cache to control the falloff of all deformers in the boundary brush. Usually this is already considered in the general brush falloff function for the rest of the brushes, but this is one of the exceptions where the brush implements its custom falloff. Reviewed By: JacquesLucke Maniphest Tasks: T84896 Differential Revision: https://developer.blender.org/D10161