/**
* Release ownership of the loops of this polygon by appending them to the
* given list. Resets the polygon to be empty.
*/
public function release(&$loops)
{
$loops = array_merge($loops, $this->loops);
$this->loops = [];
$bound = S2LatLngRect::emptya();
$this->hasHoles = false;
$this->numVertices = 0;
}
public function getRectBound()
{
if ($this->isEmpty()) {
return S2LatLngRect::emptya();
}
// Convert the axis to a (lat,lng) pair, and compute the cap angle.
$axisLatLng = new S2LatLng($this->axis);
$capAngle = $this->angle()->radians();
$allLongitudes = false;
$lat = array();
$lng = array();
$lng[0] = -S2::M_PI;
$lng[1] = S2::M_PI;
// Check whether cap includes the south pole.
$lat[0] = $axisLatLng->lat()->radians() - $capAngle;
if ($lat[0] <= -S2::M_PI_2) {
$lat[0] = -S2::M_PI_2;
$allLongitudes = true;
}
// Check whether cap includes the north pole.
$lat[1] = $axisLatLng->lat()->radians() + $capAngle;
if ($lat[1] >= S2::M_PI_2) {
$lat[1] = S2::M_PI_2;
$allLongitudes = true;
}
if (!$allLongitudes) {
// Compute the range of longitudes covered by the cap. We use the law
// of sines for spherical triangles. Consider the triangle ABC where
// A is the north pole, B is the center of the cap, and C is the point
// of tangency between the cap boundary and a line of longitude. Then
// C is a right angle, and letting a,b,c denote the sides opposite A,B,C,
// we have sin(a)/sin(A) = sin(c)/sin(C), or sin(A) = sin(a)/sin(c).
// Here "a" is the cap angle, and "c" is the colatitude (90 degrees
// minus the latitude). This formula also works for negative latitudes.
//
// The formula for sin(a) follows from the relationship h = 1 - cos(a).
$sinA = sqrt($this->height * (2 - $this->height));
$sinC = cos($axisLatLng->lat()->radians());
if ($sinA <= $sinC) {
$angleA = asin($sinA / $sinC);
$lng[0] = S2::IEEEremainder($axisLatLng->lng()->radians() - $angleA, 2 * S2::M_PI);
$lng[1] = S2::IEEEremainder($axisLatLng->lng()->radians() + $angleA, 2 * S2::M_PI);
}
}
return new S2LatLngRect(new R1Interval($lat[0], $lat[1]), new S1Interval($lng[0], $lng[1]));
}
