public Animation Linear <T>(
            FieldGetFn <T> getter,
            FieldSetFn <T> setter,
            LerpFn <T> lerp,
            T dest,
            float velocity,
            Animation.Callback callback = null)
        {
            T     origin = getter.Invoke();
            float t      = 0;

            return(new Animation(
                       () =>
            {
                origin = getter.Invoke();
                t = 0f;
                return null;
            },
                       (object state, float dt) =>
            {
                t += dt * velocity;
                setter.Invoke(lerp.Invoke(origin, dest, t));
                return state;
            },
                       (object state) => t >= 1,
                       (object state) =>
            {
                if (callback != null)
                {
                    callback.Invoke(null);
                }
            }));
        }
 public Animation Lerp <T>(
     FieldGetFn <T> getter,
     FieldSetFn <T> setter,
     LerpFn <T> lerp,
     Comparator <T> magnitude,
     T dest,
     float velocity,
     Animation.Callback callback = null)
 {
     return(new Animation(
                () => null,
                (object state, float t) =>
     {
         setter.Invoke(lerp.Invoke(getter.Invoke(), dest, velocity * t));
         return state;
     },
                (object state) => (magnitude.Invoke(getter.Invoke(), dest) < epsilon),
                (object state) =>
     {
         setter.Invoke(dest);
         if (callback != null)
         {
             callback.Invoke(state);
         }
     }
                ));
 }