A Track is a collection of straight and curved pieces of road.
These pieces are described by classes derived from Road_Segment.
Currently, we have a straight segment class (Straight_Road), and
a circle arc segment class (Arc_Road). The track is assembled so
that there are no corners where two segments join.
If you look at the code you'll find a class for a segment that smoothly
curves through a set of given points (Spline_Road). This class
has been commented out because I don't know how to do the transformation
from world coordinates to track coordinates for a spline.
The elevation and banking at any number of points on a segment can be specified. The specified points are interpolated with a cubic spline so that the transitions are smooth.
Track o---Road_Segment
^ ^
/ \
Straight_Road Arc_Road