Golang Latlong.Dist方法代码示例

func FixupComplaint(c *types.Complaint, key *datastore.Key) {
	// 0. Snag the key, so we can refer to this object later
	c.DatastoreKey = key.Encode()

	// 1. GAE datastore helpfully converts timezones to UTC upon storage; fix that
	c.Timestamp = date.InPdt(c.Timestamp)

	// 2. Compute the flight details URL, if within 24 days
	age := date.NowInPdt().Sub(c.Timestamp)
	if age < time.Hour*24 {
		// c.AircraftOverhead.Fr24Url = c.AircraftOverhead.PlaybackUrl()

		c.AircraftOverhead.Fr24Url = "http://flightaware.com/live/flight/" +
			c.AircraftOverhead.FlightNumber
		// Or: http://flightaware.com/live/flight/UAL337/history/20151215/ [0655Z/KLAX/KSFO]
		// date is UTC of departure time; might be tricky to guess :/
	}

	// 3. Compute distances, if we have an aircraft
	if c.AircraftOverhead.FlightNumber != "" {
		a := c.AircraftOverhead
		aircraftPos := geo.Latlong{a.Lat, a.Long}
		observerPos := geo.Latlong{c.Profile.Lat, c.Profile.Long}
		c.Dist2KM = observerPos.Dist(aircraftPos)
		c.Dist3KM = observerPos.Dist3(aircraftPos, a.Altitude)
	}
}

func (fr *Fr24) FindOverhead(observerPos geo.Latlong, overhead *Aircraft, grabAnything bool) (debug string, err error) {

	debug = fmt.Sprintf("*** FindOverhead for %s, at %s\n", observerPos,
		date.NowInPdt())

	// Create a bounding box that's ~40m square, centred on the input lat,long
	// This is a grievous fudge http://www.movable-type.co.uk/scripts/latlong.html
	lat_20miles := 0.3
	long_20miles := 0.35
	nearby := []Aircraft{}
	if err = fr.ListBbox(observerPos.Lat-lat_20miles, observerPos.Long-long_20miles,
		observerPos.Lat+lat_20miles, observerPos.Long+long_20miles, &nearby); err != nil {
		debug += fmt.Sprintf("Lookup error: %s\n", err)
		return
	}

	for i, a := range nearby {
		aircraftPos := geo.Latlong{a.Lat, a.Long}
		nearby[i].Dist = observerPos.Dist(aircraftPos)
		nearby[i].Dist3 = observerPos.Dist3(aircraftPos, a.Altitude)
		nearby[i].BearingFromObserver = observerPos.BearingTowards(aircraftPos)
	}
	sort.Sort(byDist3(nearby))
	debug += "** nearby list:-\n" + DebugFlightList(nearby)

	filtered := filterAircraft(nearby)
	if len(filtered) == 0 {
		debug += "** all empty after filtering\n"
		return
	}

	debug += "** filtered:-\n" + DebugFlightList(filtered)

	if grabAnything {
		*overhead = filtered[0]
		debug += "** grabbed 1st\n"
	} else {
		// closest plane has to be within 12 km to be 'overhead', and it has
		// to be 4km away from the next-closest
		if filtered[0].Dist3 < 12.0 {
			if (len(filtered) == 1) || (filtered[1].Dist3-filtered[0].Dist3) > 4.0 {
				*overhead = filtered[0]
				debug += "** selected 1st\n"
			} else {
				debug += "** 2nd was too close to 1st\n"
			}
		} else {
			debug += "** 1st was too far away\n"
		}
	}

	return
}

func (f Flight) SnapshotAt(t time.Time, pos *geo.Latlong) (*FlightSnapshot, error) {
	if len(f.Track) == 0 {
		return nil, fmt.Errorf("SnapshotAt: found no trackpoints")
	}

	t = t.UTC()
	start, end := f.Track[0].TimestampUTC, f.Track[len(f.Track)-1].TimestampUTC

	if t.Before(start) {
		return nil, fmt.Errorf("SnapshotAt: t<start (t=%s, start=%s)", t, start)
	} else if t.After(end) {
		return nil, fmt.Errorf("SnapshotAt: t>end (t=%s, end=%s)", t, end)
	}

	for i, tp := range f.Track {
		if i == len(f.Track)-1 {
			break
		}
		if tp.TimestampUTC.Before(t) && f.Track[i+1].TimestampUTC.After(t) {
			// Grab the two trackpoints that bracket our time
			snap := &FlightSnapshot{
				F:       f,
				Pos:     f.Track[i],
				NextPos: f.Track[i+1],
			}
			if pos != nil {
				snap.Reference = *pos
				snap.DistToReferenceKM = pos.Dist(f.Track[i].Latlong)
				snap.BearingToReference = float64(int64(pos.BearingTowards(f.Track[i].Latlong)))
			}

			return snap, nil
		}
	}

	return nil, fmt.Errorf("SnapshotAt: fell off the end, bad track ?")
}

func (fr *Fr24) FindAllOverhead(observerPos geo.Latlong, overhead *flightid.Aircraft, grabAnything bool) (outAll []*Aircraft, outFilt []*Aircraft, debug string, err error) {
	outAll = []*Aircraft{}
	outFilt = []*Aircraft{}

	debug = fmt.Sprintf("*** FindOverhead for %s, at %s\n", observerPos, date.NowInPdt())
	debug += fmt.Sprintf("* url: http://%s%s?array=1&bounds=%s\n", fr.host, kListUrlPath, "...")

	// Create a bounding box that's ~40m square, centred on the input lat,long
	// This is a grievous fudge http://www.movable-type.co.uk/scripts/latlong.html
	lat_20miles := 0.3
	long_20miles := 0.35
	nearby := []Aircraft{}
	if err = fr.ListBbox(observerPos.Lat-lat_20miles, observerPos.Long-long_20miles,
		observerPos.Lat+lat_20miles, observerPos.Long+long_20miles, &nearby); err != nil {
		debug += fmt.Sprintf("Lookup error: %s\n", err)
		return
	}

	for i, a := range nearby {
		// Hack for Surf Air; promote callsigns into (invalid_ flightnumbers, so they don't get stripped
		if a.FlightNumber == "" && regexp.MustCompile("^URF\\d+$").MatchString(a.Callsign) {
			nearby[i].FlightNumber = a.Callsign
		} else if a.FlightNumber != "" {
			if _, _, err := fdb.ParseIata(a.FlightNumber); err != nil {
				debug += "** saw bad flightnumber '" + a.FlightNumber + "' from fr24\n"
				nearby[i].FlightNumber = ""
			}
		}

		aircraftPos := geo.Latlong{a.Lat, a.Long}
		nearby[i].Dist = observerPos.Dist(aircraftPos)
		nearby[i].Dist3 = observerPos.Dist3(aircraftPos, a.Altitude)
		nearby[i].BearingFromObserver = observerPos.BearingTowards(aircraftPos)
	}
	sort.Sort(byDist3(nearby))
	debug += "** nearby list:-\n" + DebugFlightList(nearby)

	filtered := filterAircraft(nearby)
	if len(filtered) == 0 {
		debug += "** all empty after filtering\n"
		return
	}

	for i, _ := range nearby {
		outAll = append(outAll, &nearby[i])
	}
	for i, _ := range filtered {
		outFilt = append(outFilt, &filtered[i])
	}

	debug += "** filtered:-\n" + DebugFlightList(filtered)

	if grabAnything {
		filtered[0].IntoFlightIdAircraft(overhead)
		debug += "** grabbed 1st\n"
	} else {
		// closest plane has to be within 12 km to be 'overhead', and it has
		// to be 4km away from the next-closest
		if filtered[0].Dist3 < 12.0 {
			if (len(filtered) == 1) || (filtered[1].Dist3-filtered[0].Dist3) > 4.0 {
				filtered[0].IntoFlightIdAircraft(overhead)
				debug += "** selected 1st\n"
			} else {
				debug += "** 2nd was too close to 1st\n"
			}
		} else {
			debug += "** 1st was too far away\n"
		}
	}

	return
}