al_set_haptic_autocenter man page
al_set_haptic_autocenter — Allegro 5 API
#include <allegro5/allegro.h> bool al_set_haptic_autocenter(ALLEGRO_HAPTIC *hap, double intensity)
Turns on or off the automatic centering feature of the haptic device if supported. Depending on the device automatic centering may ensure that the axes of the device are centered again automatically after playing a haptic effect. The intensity parameter should be passed with a value between 0.0 and 1.0. The value 0.0 means automatic centering is disabled, and 1.0 means full strength automatic centering. Any value in between those two extremes will result in partial automatic centering. Some platforms do not support partial automatic centering. If that is the case, a value of less than 0.5 will turn it off, while a value equal to or higher to 0.5 will turn it on. Returns true if set sucessfully, false if not. Can only work if al_get_haptic_capabilities(3) returns a value that has ALLEGRO_HAPTIC_AUTOCENTER(3)ALLEGRO_HAPTIC_CONSTANTS(3) set. If not, this function returns false.
[Unstable API]: Perhaps could be simplified due to limited support for all the exposed features across all of the platforms. Awaiting feedback from users.