I have a class called TravelDisruption which has, among other things,
coordinates for start and end points. I'm placing these objects in a
Continuous2D field using the start point as the location and I've written a
TravelDisruptionPortrayal2D which draws it. The problem is that it doesn't
get drawn unless the start point is on the screen. How do I fix this so it
draws when any of it is on-screen?