Constant Force based on brightness gradient (Full Force Feedback Mouse Required). Only for default effect of Edge, Line & Corner. Constant Force based on brightness gradient: a Constant force is a steady force pushing you in a single direction. Steering wheels, joysticks and a full force feedback mouse can simulate Constant forces. A tactile feedback mouse cannot. Constant force based on brightness gradient. It's a steady force pushing you in a single direction (Steering wheels, joysticks or full force feedback mouse required). Only for default effect.