private bool FindRouteAttempt(RouteSeachRegion regionPara, RouteFindingData findRouteData)
{
findRouteData.Init(regionPara.StartPtIndex);
var unvisited = new MinHeap <int, double>();
unvisited.Add(regionPara.StartPtIndex, 0.0);
while (unvisited.Count > 0)
{
var current = unvisited.ExtractMin();
if (current.Key == regionPara.EndPtIndex)
{
return(true);
}
UpdateNeighbors(
current.Key,
regionPara,
findRouteData,
unvisited,
current.Value);
}
return(false); //Route not found.
}
/// <summary>
/// Finds a route from the waypoint in wptList with
/// index startPtIndex, to endPtIndex.
/// The two indices must not be identical.
/// </summary>
/// <exception cref="RouteNotFoundException"></exception>
/// <exception cref="ArgumentException"></exception>
private Route GetRoute(int startPtIndex, int endPtIndex)
{
if (startPtIndex == endPtIndex)
{
throw new ArgumentException("Start point cannot be the same as end point.");
}
var FindRouteData = new RouteFindingData(wptList.NodeIndexUpperBound + 1);
var region = new RouteSeachRegion(wptList, startPtIndex, endPtIndex);
// The max distance must be larger than 0. Otherwise this method cannot
// find a route from between two different points with distance zero.
region.MaxDistanceSum = Math.Max(50.0, region.DirectDistance * 1.25);
bool routeFound = false;
while (!routeFound && region.MaxDistanceSum <= RouteSeachRegion.MaxPossibleDistanceSum)
{
routeFound = FindRouteAttempt(region, FindRouteData);
region.MaxDistanceSum *= 1.5;
}
if (routeFound)
{
return(ExtractRoute(FindRouteData, startPtIndex, endPtIndex));
}
throw new RouteNotFoundException(
$"No route exists between {wptList[startPtIndex].ID} " +
$"and {wptList[endPtIndex].ID}.");
}
private bool WptWithinRange(RouteFindingData findRouteData,
int wptIndex, RouteSeachRegion region)
{
var data = findRouteData.WaypointData;
if (data[wptIndex].WithInRange == InRange.Unknown)
{
// Suppose the orig and dest rwys are already in the wptList
var p = region;
bool inRange =
wptList.Distance(p.StartPtIndex, wptIndex) +
wptList.Distance(p.EndPtIndex, wptIndex) <
p.MaxDistanceSum;
data[wptIndex].WithInRange = inRange ? InRange.Yes : InRange.No;
}
return((int)data[wptIndex].WithInRange == 1);
}
private void UpdateNeighbors(
int currentWptIndex,
RouteSeachRegion regionPara,
RouteFindingData findRouteData,
MinHeap <int, double> unvisited,
double currentDis)
{
foreach (var edgeIndex in wptList.EdgesFrom(currentWptIndex))
{
var wptData = findRouteData.WaypointData;
var edge = wptList.GetEdge(edgeIndex);
int index = edge.ToNodeIndex;
var countryCode = wptList[index].CountryCode;
if (WptWithinRange(findRouteData, index, regionPara) &&
avoidedCountry.Contains(countryCode) == false)
{
double newDis = currentDis + GetEdgeDistance(edge);
if (wptData[index].CurrentDistance == double.PositiveInfinity)
{
// The node was never touched.
unvisited.Add(index, newDis);
wptData[index] = new RouteFindingData.WaypointStatus(
edge,
newDis,
InRange.Yes);
}
else if (unvisited.ContainsKey(index) && newDis < unvisited[index])
{
unvisited.ChangeValue(index, newDis);
wptData[index] = new RouteFindingData.WaypointStatus(
edge,
newDis,
InRange.Yes);
}
}
}
}
/// <summary>
/// Finds a route from the waypoint in wptList with
/// index startPtIndex, to endPtIndex.
/// </summary>
/// <exception cref="RouteNotFoundException"></exception>
private Route GetRoute(int startPtIndex, int endPtIndex)
{
var FindRouteData = new RouteFindingData(wptList.NodeIndexUpperBound + 1);
var region = new RouteSeachRegion(wptList, startPtIndex, endPtIndex);
region.MaxDistanceSum = region.DirectDistance * 1.25;
bool routeFound = false;
while (!routeFound && region.MaxDistanceSum <= RouteSeachRegion.MaxPossibleDistanceSum)
{
routeFound = FindRouteAttempt(region, FindRouteData);
region.MaxDistanceSum *= 1.5;
}
if (routeFound)
{
return(ExtractRoute(FindRouteData, startPtIndex, endPtIndex));
}
throw new RouteNotFoundException(
$"No route exists between {wptList[startPtIndex].ID} " +
$"and {wptList[endPtIndex].ID}.");
}
