Custom Vignette animation

Hi all! I ve been trying to figure out for some days to create a post process effect and I can’t achieve it. I dont really know if Im solving this problem correctly or I should use widgets…

My purpose is to create switch between 2 modes:

  • In the first mode everything is normal

  • In the second mode, I would like to have a “custom vignette”. A texture of roots and leaves at the edges of the screen. Vía widget I managed to fade it and fade them out, but my intention is to create an effect where when I switch between these two modes, those roots animate themself and they grow from the outside of the screen to the inside. Once they are inside, they have a loop movement and lastly, when we blend out from this mode, those roots decrease.

I dont have a clue if I should try to do this through Screen Effects, post process effects, widget…

I would appreciate if someone could help me figure out how to do it.

Thanks in advance.