/**
* filters out nonessential points. A point is nonessential if it affects the path taken by less
* than 5 meters
*
* @return The checkpoints of the trail in this map
*/
public TTLocation[] getCheckpoints() {
// starting point always relevant//
ArrayList<TTLocation> checkpointList = new ArrayList<TTLocation>();
checkpointList.add(locations[0]);
int relevantPointIndex = 0;
for (int locationIndex = 2; locationIndex < locations.length; locationIndex++) {
TTLocation ptInQuestion = locations[locationIndex - 1];
TTLocation relevantPt = locations[relevantPointIndex];
// distance from the last relevant to the point in question//
float distanceTo =
relevantPt.distanceTo(ptInQuestion.getLongitude(), ptInQuestion.getLatitude());
// if the point is less than 5m away, it can't affect the trail by more than 5m//
if (distanceTo < 5) {
continue;
}
// difference between the bearing from the relevant point to the point in question
// and the bearing from the relevant point to the point after the point in question
float bearingDifference =
Math.abs(
relevantPt.bearingTo(ptInQuestion.getLongitude(), ptInQuestion.getLatitude())
- relevantPt.bearingTo(
locations[locationIndex].getLongitude(),
locations[locationIndex].getLatitude()));
// distance away from the point in question that the new path will take//
double distanceOff = Math.sin(bearingDifference) * distanceTo;
if (distanceOff > 5) {
checkpointList.add(ptInQuestion);
relevantPointIndex = locationIndex - 1;
}
}
// the last point is always relevant and, as a result of the loop conditions,
// never added by the loop//
checkpointList.add(locations[locations.length - 1]);
TTLocation[] array = new TTLocation[checkpointList.size()];
return checkpointList.toArray(array);
}
