/** * Given (i, j) coordinates that may be out of bounds, normalize them by * returning the corresponding neighbor cell on an adjacent face. */ private static function fromFaceIJWrap($face, $i, $j) { // Convert i and j to the coordinates of a leaf cell just beyond the // boundary of this face. This prevents 32-bit overflow in the case // of finding the neighbors of a face cell, and also means that we // don't need to worry about the distinction between (s,t) and (u,v). $i = max(-1, min(self::MAX_SIZE, $i)); $j = max(-1, min(self::MAX_SIZE, $j)); // Find the (s,t) coordinates corresponding to (i,j). At least one // of these coordinates will be just outside the range [0, 1]. $kScale = 1.0 / self::MAX_SIZE; $s = $kScale * (($i << 1) + 1 - self::MAX_SIZE); $t = $kScale * (($j << 1) + 1 - self::MAX_SIZE); // Find the leaf cell coordinates on the adjacent face, and convert // them to a cell id at the appropriate level. $p = S2Projections::faceUvToXyz($face, $s, $t); $face = S2Projections::xyzToFace($p); $st = S2Projections::validFaceXyzToUv($face, $p); return self::fromFaceIJ($face, self::stToIJ($st->x()), self::stToIJ($st->y())); }
private function getLongitude($i, $j) { $p = S2Projections::faceUvToXyz($this->face, $this->uv[0][$i], $this->uv[1][$j]); return atan2($p->y, $p->x); }