/// <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 = new Point3D();
return(false);
}
// While we still have paths to evaluate.
while (pPending.Size > 0 && (pEvaluated.Size == 0 || (pPending.MinKey < pEvaluated.MinKey)))
{
// If there are pending paths possibly closer than the nearest evaluated point, check it out
KDNode pCursor = pPending.Min;
pPending.RemoveMin();
// Descend the tree, recording paths not taken
while (!pCursor.IsLeaf)
{
KDNode pNotTaken;
// If the seach point is larger, select the right path.
if (tSearchPoint[pCursor.iSplitDimension] > pCursor.fSplitValue)
{
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.
double fDistance = kDistanceFunction.DistanceToRectangle(tSearchPoint, pNotTaken.tMinBound, pNotTaken.tMaxBound);
// If it is greater than the threshold, skip.
if (fThreshold >= 0 && fDistance > fThreshold)
{
//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)
{
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.
double fDistance = kDistanceFunction.Distance(pCursor.tPoints[0], tSearchPoint);
// Skip if the point exceeds the threshold.
// Technically this should never happen, but be prescise.
if (fThreshold >= 0 && fDistance >= fThreshold)
{
continue;
}
// Add the point if either need more points or it's closer than furthest on list so far.
if (pEvaluated.Size < iPointsRemaining || fDistance <= pEvaluated.MaxKey)
{
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.tData[i]);
}
// Otherwise insert.
else
{
pEvaluated.Insert(fDistance, pCursor.tData[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.
double fDistance = kDistanceFunction.Distance(pCursor.tPoints[i], tSearchPoint);
// Skip if it exceeds the threshold.
if (fThreshold >= 0 && fDistance >= fThreshold)
{
continue;
}
// Insert the point if we have more to take.
if (pEvaluated.Size < iPointsRemaining)
{
pEvaluated.Insert(fDistance, pCursor.tData[i]);
}
// Otherwise replace the max.
else if (fDistance < pEvaluated.MaxKey)
{
pEvaluated.ReplaceMax(fDistance, pCursor.tData[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);
}
