+double FGAIBase::UpdateRadar(FGAIManager* manager) {
+ bool control = fgGetBool("/sim/controls/radar", true);
+
+ if(!control) return 0;
+
+ double radar_range_ft2 = fgGetDouble("/instrumentation/radar/range");
+ bool force_on = fgGetBool("/instrumentation/radar/debug-mode", false);
+ radar_range_ft2 *= SG_NM_TO_METER * SG_METER_TO_FEET * 1.1; // + 10%
+ radar_range_ft2 *= radar_range_ft2;
+
+ double user_latitude = manager->get_user_latitude();
+ double user_longitude = manager->get_user_longitude();
+ double lat_range = fabs(pos.getLatitudeDeg() - user_latitude) * ft_per_deg_lat;
+ double lon_range = fabs(pos.getLongitudeDeg() - user_longitude) * ft_per_deg_lon;
+ double range_ft2 = lat_range*lat_range + lon_range*lon_range;
+
+ //
+ // Test whether the target is within radar range.
+ //
+ in_range = (range_ft2 && (range_ft2 <= radar_range_ft2));
+
+ if ( in_range || force_on ) {
+ props->setBoolValue("radar/in-range", true);
+
+ // copy values from the AIManager
+ double user_altitude = manager->get_user_altitude();
+ double user_heading = manager->get_user_heading();
+ double user_pitch = manager->get_user_pitch();
+ //double user_yaw = manager->get_user_yaw();
+ //double user_speed = manager->get_user_speed();
+
+ // calculate range to target in feet and nautical miles
+ double range_ft = sqrt( range_ft2 );
+ range = range_ft / 6076.11549;
+
+ // calculate bearing to target
+ if (pos.getLatitudeDeg() >= user_latitude) {
+ bearing = atan2(lat_range, lon_range) * SG_RADIANS_TO_DEGREES;
+ if (pos.getLongitudeDeg() >= user_longitude) {
+ bearing = 90.0 - bearing;
+ } else {
+ bearing = 270.0 + bearing;
+ }
+ } else {
+ bearing = atan2(lon_range, lat_range) * SG_RADIANS_TO_DEGREES;
+ if (pos.getLongitudeDeg() >= user_longitude) {
+ bearing = 180.0 - bearing;
+ } else {
+ bearing = 180.0 + bearing;
+ }
+ }
+
+ // This is an alternate way to compute bearing and distance which
+ // agrees with the original scheme within about 0.1 degrees.
+ //
+ // Point3D start( user_longitude * SGD_DEGREES_TO_RADIANS,
+ // user_latitude * SGD_DEGREES_TO_RADIANS, 0 );
+ // Point3D dest( pos.getLongitudeRad(), pos.getLatitudeRad(), 0 );
+ // double gc_bearing, gc_range;
+ // calc_gc_course_dist( start, dest, &gc_bearing, &gc_range );
+ // gc_range *= SG_METER_TO_NM;
+ // gc_bearing *= SGD_RADIANS_TO_DEGREES;
+ // printf("orig b = %.3f %.2f gc b= %.3f, %.2f\n",
+ // bearing, range, gc_bearing, gc_range);
+
+ // calculate look left/right to target, without yaw correction
+ horiz_offset = bearing - user_heading;
+ if (horiz_offset > 180.0) horiz_offset -= 360.0;
+ if (horiz_offset < -180.0) horiz_offset += 360.0;
+
+ // calculate elevation to target
+ elevation = atan2( altitude_ft - user_altitude, range_ft ) * SG_RADIANS_TO_DEGREES;
+
+ // calculate look up/down to target
+ vert_offset = elevation - user_pitch;
+
+ /* this calculation needs to be fixed, but it isn't important anyway
+ // calculate range rate
+ double recip_bearing = bearing + 180.0;
+ if (recip_bearing > 360.0) recip_bearing -= 360.0;
+ double my_horiz_offset = recip_bearing - hdg;
+ if (my_horiz_offset > 180.0) my_horiz_offset -= 360.0;
+ if (my_horiz_offset < -180.0) my_horiz_offset += 360.0;
+ rdot = (-user_speed * cos( horiz_offset * SG_DEGREES_TO_RADIANS ))
+ +(-speed * 1.686 * cos( my_horiz_offset * SG_DEGREES_TO_RADIANS ));
+ */
+
+ // now correct look left/right for yaw
+ // horiz_offset += user_yaw; // FIXME: WHY WOULD WE WANT TO ADD IN SIDE-SLIP HERE?
+
+ // calculate values for radar display
+ y_shift = range * cos( horiz_offset * SG_DEGREES_TO_RADIANS);
+ x_shift = range * sin( horiz_offset * SG_DEGREES_TO_RADIANS);
+ rotation = hdg - user_heading;
+ if (rotation < 0.0) rotation += 360.0;
+ ht_diff = altitude_ft - user_altitude;
+
+ }
+
+ return range_ft2;
+}