On a full bathroom plumbing, do i need to vent each drain individualy, or can i just use the 3" to the roof?

I am doing a new full bathroom. i have the sink vented to a 3" roof vent, i have a toilet, shower, and bathtub connected to a 3" drain pipe and vented with a 3" pipe to roof. Do i need to vent the shower and bathtub individually and connected them to the 3" vent or is the 3" vent from the main line enough?