static int
get_target_latlon(stateVector *st, double look, double *tlat, double *tlon)
{
// satellite height, from the state vector
double ht = vecMagnitude(st->pos);
// earth radius, calculate from WGS84 values, and approx latitude
double re = 6378137.0;
double rp = 6356752.31414;
double lat = asin(st->pos.z/ht);
double er = re*rp/sqrt(rp*rp*cos(lat)*cos(lat)+re*re*sin(lat)*sin(lat));
// calculate slant range by law of cosines
// (where we know two sides, but not the angle between them)
double D = er*er - ht*ht*sin(look)*sin(look);
if (D < 0)
return 0; // can't see the Earth from here
double sr1 = ht*cos(look) + sqrt(D);
double sr2 = ht*cos(look) - sqrt(D);
double sr = sr1>sr2 ? sr2 : sr1;
// target position, first in inertial coords, then convert to lat/lon
vector target;
get_target_position(st, look, 0, sr, &target);
double glat; // geocentric
cart2sph(target,&er,&glat,tlon);
// tlon should be -180,180
// tlat needs to be geodetic
// both should be degrees
*tlon *= R2D;
if (*tlon < -180.) *tlon += 360.;
*tlat = R2D*atan(tan(glat)*re*re/(rp*rp));
return 1;
}
void KheperaView::print_targetInfo(){
if (is_target_set()){
Point targetCenter = get_target_position();
View::print_targetInfo(_frame, get_height(), get_width(), targetCenter);
}
}
