/**
* Convert a geocentric point from the WGS84 datum.
*/
public function fromWgs84(Geocentric $point)
{
if ($this->type == static::TYPE_3TERM) {
$x = $point->x - $this->params[0];
$y = $point->y - $this->params[1];
$z = $point->z - $this->params[2];
} elseif ($this->type == static::TYPE_7TERM) {
$Dx_BF = $this->params[0];
$Dy_BF = $this->params[1];
$Dz_BF = $this->params[2];
// These need converting from seconds of arc to radians.
$Rx_BF = $this->params[3] * static::SEC_TO_RAD;
$Ry_BF = $this->params[4] * static::SEC_TO_RAD;
$Rz_BF = $this->params[5] * static::SEC_TO_RAD;
// Convert parts per million to a multiplier
$M_BF = 1 + $this->params[6] * static::PPM_TO_MULT;
$x_tmp = ($point->x - $Dx_BF) / $M_BF;
$y_tmp = ($point->y - $Dy_BF) / $M_BF;
$z_tmp = ($point->z - $Dz_BF) / $M_BF;
$x = $x_tmp + $Rz_BF * $y_tmp - $Ry_BF * $z_tmp;
$y = -$Rz_BF * $x_tmp + $y_tmp + $Rx_BF * $z_tmp;
$z = $Ry_BF * $x_tmp - $Rx_BF * $y_tmp + $z_tmp;
} else {
throw new Excreption('Unknown datum transformation parameter type');
}
// Give the point the new datum.
$new_point = $point->withOrdinates($x, $y, $z)->withDatum($this);
return $new_point;
}
