/**
* Calculate error distance, between last through this to next,
* if this node is removed. This metric provides for Douglas-Peuker
* thinning.
*
* @param last Point previous in time to this node
* @param node This node
* @param next Point succeeding this node
*
* @return Distance error if this node is thinned
*/
static unsigned DistanceMetric(const TracePoint &last,
const TracePoint &node,
const TracePoint &next) {
const int d_this = last.FlatDistanceTo(node) + node.FlatDistanceTo(next);
const int d_rem = last.FlatDistanceTo(next);
return abs(d_this - d_rem);
}
TraceDelta(const TracePoint &p_last, const TracePoint &p,
const TracePoint &p_next)
:point(p),
elim_time(TimeMetric(p_last, p, p_next)),
elim_distance(DistanceMetric(p_last, p, p_next)),
delta_distance(p.FlatDistanceTo(p_last))
{
assert(elim_distance != null_delta);
}
void Update(const TracePoint &p_last, const TracePoint &p_next) {
elim_time = TimeMetric(p_last, point, p_next);
elim_distance = DistanceMetric(p_last, point, p_next);
delta_distance = point.FlatDistanceTo(p_last);
}
