/// <summary>
/// Check for the next iterator item.
/// </summary>
/// <returns>True if we have one, false if not.</returns>
public bool MoveNext()
{
// Bail if we are finished.
if (iPointsRemaining == 0)
{
_Current = default(LabelType);
return(false);
}
// While we still have paths to evaluate.
while (pPending.Size > 0 && (pEvaluated.Size == 0 || (pPending.MinKey.CompareTo(pEvaluated.MinKey) == -1)))
{
// If there are pending paths possibly closer than the nearest evaluated point, check it out
KDNode <DomainType, DistanceType, LabelType> pCursor = pPending.Min;
pPending.RemoveMin();
// Descend the tree, recording paths not taken
while (!pCursor.IsLeaf)
{
KDNode <DomainType, DistanceType, LabelType> pNotTaken;
// If the seach point is larger, select the right path.
if (search_point[pCursor.d_split_dimension].CompareTo(pCursor.d_split_value) == 1)
{
pNotTaken = pCursor.pLeft;
pCursor = pCursor.pRight;
}
else
{
pNotTaken = pCursor.pRight;
pCursor = pCursor.pLeft;
}
// Calculate the shortest distance between the search point and the min and max bounds of the kd-node.
DistanceType fDistance = distance_function.ComputeToRectangle(search_point, pNotTaken.tMinBound, pNotTaken.tMaxBound);
// If it is greater than or equal to the threshold, skip.
if (d_use_threshold && (fDistance.CompareTo(fThreshold) != -1))
{
//pPending.Insert(fDistance, pNotTaken);
continue;
}
// Only add the path we need more points or the node is closer than furthest point on list so far.
// if (pEvaluated.Size < iPointsRemaining || fDistance <= pEvaluated.MaxKey)
if (pEvaluated.Size < iPointsRemaining || fDistance.CompareTo(pEvaluated.MaxKey) != 1)
{
pPending.Insert(fDistance, pNotTaken);
}
}
// If all the points in this KD node are in one place.
if (pCursor.bSinglePoint)
{
// Work out the distance between this point and the search point.
DistanceType fDistance = distance_function.Compute(pCursor.d_points[0], search_point);
// If it is greater than or equal to the threshold, skip.
if (d_use_threshold && (fDistance.CompareTo(fThreshold) != -1))
{
continue;
}
// Add the point if either need more points or it's closer than furthest on list so far.
if (pEvaluated.Size < iPointsRemaining || (fDistance.CompareTo(pEvaluated.MaxKey) != 1))
{
for (int i = 0; i < pCursor.Size; ++i)
{
// If we don't need any more, replace max
if (pEvaluated.Size == iPointsRemaining)
{
pEvaluated.ReplaceMax(fDistance, pCursor.d_values[i]);
}
// Otherwise insert.
else
{
pEvaluated.Insert(fDistance, pCursor.d_values[i]);
}
}
}
}
// If the points in the KD node are spread out.
else
{
// Treat the distance of each point seperately.
for (int i = 0; i < pCursor.Size; ++i)
{
// Compute the distance between the points.
DistanceType fDistance = distance_function.Compute(pCursor.d_points[i], search_point);
// If it is greater than or equal to the threshold, skip.
if (d_use_threshold && (fDistance.CompareTo(fThreshold) != -1))
{
continue;
}
// Insert the point if we have more to take.
if (pEvaluated.Size < iPointsRemaining)
{
pEvaluated.Insert(fDistance, pCursor.d_values[i]);
}
// Otherwise replace the max.
else if (fDistance.CompareTo(pEvaluated.MaxKey) == -1)
{
pEvaluated.ReplaceMax(fDistance, pCursor.d_values[i]);
}
}
}
}
// Select the point with the smallest distance.
if (pEvaluated.Size == 0)
{
return(false);
}
iPointsRemaining--;
_CurrentDistance = pEvaluated.MinKey;
_Current = pEvaluated.Min;
pEvaluated.RemoveMin();
return(true);
}
