/**
* Default constructor used only internally.
*/
public function __construct($p = null)
{
if ($p instanceof S2Point) {
$this->init(S2CellId::fromPoint($p));
} else {
if ($p instanceof S2LatLng) {
$this->init(S2CellId::fromLatLng($p));
} else {
if ($p instanceof S2CellId) {
$this->init($p);
}
}
}
}
/** Computes a set of initial candidates that cover the given region. */
private function getInitialCandidates()
{
// Optimization: if at least 4 cells are desired (the normal case),
// start with a 4-cell covering of the region's bounding cap. This
// lets us skip quite a few levels of refinement when the region to
// be covered is relatively small.
if ($this->maxCells >= 4) {
// Find the maximum level such that the bounding cap contains at most one
// cell vertex at that level.
$cap = $this->region->getCapBound();
$level = min(S2Projections::MIN_WIDTH()->getMaxLevel(2 * $cap->angle()->radians()), min($this->maxLevel(), S2CellId::MAX_LEVEL - 1));
if ($this->levelMod() > 1 && $level > $this->minLevel()) {
$level -= ($level - $this->minLevel()) % $this->levelMod();
}
// We don't bother trying to optimize the level == 0 case, since more than
// four face cells may be required.
if ($level > 0) {
// Find the leaf cell containing the cap axis, and determine which
// subcell of the parent cell contains it.
/** @var S2CellId[] $base */
$base = array();
$s2point_tmp = $cap->axis();
$id = S2CellId::fromPoint($s2point_tmp);
$id->getVertexNeighbors($level, $base);
for ($i = 0; $i < count($base); ++$i) {
// printf("(face=%s pos=%s level=%s)\n", $base[$i]->face(), dechex($base[$i]->pos()), $base[$i]->level());
// echo "new S2Cell(base[i])\n";
$cell = new S2Cell($base[$i]);
// echo "neighbour cell: " . $cell . "\n";
$c = $this->newCandidate($cell);
// if ($c !== null)
// echo "addCandidato getInitialCandidates: " . $c->cell->id() . "\n";
$this->addCandidate($c);
}
// echo "\n\n\n";
return;
}
}
// Default: start with all six cube faces.
$face_cells = self::FACE_CELLS();
for ($face = 0; $face < 6; ++$face) {
$c = $this->newCandidate($face_cells[$face]);
echo "addCandidato getInitialCandidates_default: " . $c->cell->id() . "\n";
$this->addCandidate($c);
}
}