Spacey, the above illustration is a bit more complex that your average two road intersection. However, let us assume you are in the red car at the bottom and intend to follow the red line. You are most unlikely to collide with a vehicle in front of road 'e' and less likely with cars at b, c or d, so it's safe to enter the roundabout. Cars at f are the ones you need to concentrate on. A car entering from b could well exit at d, or f, so there is no likelyhood of a collision, and you don't have to wait for them to exit.
If you want an intersection that confuses interstaters, come to Melbourne and try a hook turn, where you turn right from the left lane. These are designed to allow trams through progress without interruption. The turning car waits for the lights to change.