m base object
            % Assumption: cutoff ratio applies to particle radius
            switch (this.pwInteractionType(p,w))
                case 1
                    this.kinpw_sph_line.setRelPos(p,w);
                    if (addVL && this.kinpw_sph_line.separ < this.verlet_dist)
                        p.verlet_w(end+1) = w;
                    end
                    if (this.kinpw_sph_line.separ >= this.cutoff * p.radius)
                        return;
                    end
                    k