@interface RealityKit.__RKEntitySetOpacityAction : RealityKit.__RKEntityVisibilityAction {
    void /* unknown type, empty encoding */ duration;
    void /* unknown type, empty encoding */ opacity;
    void /* unknown type, empty encoding */ fadeSubscription;
    void /* unknown type, empty encoding */ initialOpacity;
    void /* unknown type, empty encoding */ stepSize;
}

- (id)copyWithZone:(void *)a0;

@end