/// <summary>
/// Given a normalized coordinate in multiple dimensions, calculate its derived key for given level
/// </summary>
private long?DerivedValueFor(long[] normalizedValues, int level)
{
AssertValidLevel(level);
long derivedValue = 0;
long mask = 1L << (_maxLevel - 1);
// The starting curve depends on the dimensions
CurveRule currentCurve = RootCurve();
for (int i = 1; i <= _maxLevel; i++)
{
int bitIndex = _maxLevel - i;
int npoint = 0;
foreach (long val in normalizedValues)
{
npoint = npoint << 1 | ( int )((val & mask) >> bitIndex);
}
int derivedIndex = currentCurve.IndexForNPoint(npoint);
derivedValue = (derivedValue << _nbrDim) | derivedIndex;
mask = mask >> 1;
currentCurve = currentCurve.ChildAt(derivedIndex);
}
if (level < _maxLevel)
{
derivedValue = derivedValue << (_nbrDim * _maxLevel - level);
}
return(derivedValue);
}
/// <summary>
/// Given a derived key, find the normalized coordinate it corresponds to on a specific level
/// </summary>
internal virtual long[] NormalizedCoordinateFor(long derivedValue, int level)
{
AssertValidLevel(level);
long mask = _initialNormMask;
long[] coordinate = new long[_nbrDim];
// First level is a single curveUp
CurveRule currentCurve = RootCurve();
for (int i = 1; i <= level; i++)
{
int bitIndex = _maxLevel - i;
int derivedIndex = ( int )((derivedValue & mask) >> bitIndex * _nbrDim);
int npoint = currentCurve.NpointForIndex(derivedIndex);
int[] bitValues = bitValues(npoint);
for (int dim = 0; dim < _nbrDim; dim++)
{
coordinate[dim] = coordinate[dim] << 1 | bitValues[dim];
}
mask = mask >> _nbrDim;
currentCurve = currentCurve.ChildAt(derivedIndex);
}
if (level < _maxLevel)
{
for (int dim = 0; dim < _nbrDim; dim++)
{
coordinate[dim] = coordinate[dim] << _maxLevel - level;
}
}
return(coordinate);
}
private void AddTilesIntersectingEnvelopeAt(SpaceFillingCurveConfiguration config, SpaceFillingCurveMonitor monitor, int depth, int maxDepth, SearchEnvelope search, SearchEnvelope currentExtent, CurveRule curve, long left, long right, List <LongRange> results)
{
if (right - left == 1)
{
long[] coord = NormalizedCoordinateFor(left, _maxLevel);
if (search.Contains(coord))
{
LongRange current = (results.Count > 0) ? results[results.Count - 1] : null;
if (current != null && current.Max == left - 1)
{
current.ExpandToMax(left);
}
else
{
current = new LongRange(left);
results.Add(current);
}
if (monitor != null)
{
monitor.AddRangeAtDepth(depth);
monitor.AddToCoveredArea(currentExtent.Area);
}
}
}
else if (search.Intersects(currentExtent))
{
double overlap = search.FractionOf(currentExtent);
if (config.StopAtThisDepth(overlap, depth, maxDepth))
{
// Note that LongRange upper bound is inclusive, hence the '-1' in several places
LongRange current = (results.Count > 0) ? results[results.Count - 1] : null;
if (current != null && current.Max == left - 1)
{
current.ExpandToMax(right - 1);
}
else
{
current = new LongRange(left, right - 1);
results.Add(current);
}
if (monitor != null)
{
monitor.AddRangeAtDepth(depth);
monitor.AddToCoveredArea(currentExtent.Area);
}
}
else
{
long width = (right - left) / _quadFactor;
for (int i = 0; i < _quadFactor; i++)
{
int npoint = curve.NpointForIndex(i);
SearchEnvelope quadrant = currentExtent.Quadrant(BitValues(npoint));
AddTilesIntersectingEnvelopeAt(config, monitor, depth + 1, maxDepth, search, quadrant, curve.ChildAt(i), left + i * width, left + (i + 1) * width, results);
}
}
}
}
