158 lines
3.3 KiB
Go
158 lines
3.3 KiB
Go
// Package gpx 解析 GPX 轨迹文件（标准 WGS-84 坐标），
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// 用来给 rond 的「地点到地点」直线位移补上真实路径。
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package gpx
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import (
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"encoding/xml"
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"errors"
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"fmt"
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"math"
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"strings"
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"time"
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)
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// Track 是一条轨迹（GPX 的 trk / rte），坐标是 WGS-84。
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type Track struct {
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Name string
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Points []Point
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Time time.Time
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}
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type Point struct {
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Lat float64
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Lon float64
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Ele float64
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T time.Time
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}
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type gpxDoc struct {
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XMLName xml.Name `xml:"gpx"`
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Name string `xml:"metadata>name"`
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Trks []trk `xml:"trk"`
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Rtes []rte `xml:"rte"`
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}
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type trk struct {
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Name string `xml:"name"`
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Trkseg []trkseg `xml:"trkseg"`
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}
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type trkseg struct {
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Pts []wpt `xml:"trkpt"`
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}
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type rte struct {
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Name string `xml:"name"`
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Pts []wpt `xml:"rtept"`
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}
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type wpt struct {
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Lat float64 `xml:"lat,attr"`
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Lon float64 `xml:"lon,attr"`
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Ele float64 `xml:"ele"`
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T string `xml:"time"`
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}
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// Parse 解析 GPX 文本，返回其中的全部轨迹。trk 优先，没有则退回 rte。
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func Parse(data []byte) ([]Track, error) {
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var doc gpxDoc
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if err := xml.Unmarshal(data, &doc); err != nil {
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return nil, fmt.Errorf("GPX 解析失败: %w", err)
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}
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var out []Track
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base := strings.TrimSpace(doc.Name)
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for _, t := range doc.Trks {
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tr := Track{Name: firstNonEmpty(strings.TrimSpace(t.Name), base)}
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for _, seg := range t.Trkseg {
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for _, p := range seg.Pts {
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if p.Lat == 0 && p.Lon == 0 {
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continue
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}
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pt := Point{Lat: p.Lat, Lon: p.Lon, Ele: p.Ele}
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if p.T != "" {
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pt.T, _ = time.Parse(time.RFC3339, strings.TrimSpace(p.T))
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}
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tr.Points = append(tr.Points, pt)
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}
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}
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if len(tr.Points) > 1 {
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if tr.Time.IsZero() {
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tr.Time = tr.Points[0].T
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}
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out = append(out, tr)
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}
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}
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for _, r := range doc.Rtes {
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tr := Track{Name: firstNonEmpty(strings.TrimSpace(r.Name), base)}
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for _, p := range r.Pts {
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if p.Lat == 0 && p.Lon == 0 {
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continue
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}
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pt := Point{Lat: p.Lat, Lon: p.Lon}
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if p.T != "" {
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pt.T, _ = time.Parse(time.RFC3339, strings.TrimSpace(p.T))
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}
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tr.Points = append(tr.Points, pt)
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}
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if len(tr.Points) > 1 {
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if tr.Time.IsZero() {
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tr.Time = tr.Points[0].T
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}
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out = append(out, tr)
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}
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}
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if len(out) == 0 {
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return nil, errors.New("文件里没有找到轨迹点（需要 trk/trkpt 或 rte/rtept）")
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}
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return out, nil
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}
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func firstNonEmpty(vals ...string) string {
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for _, v := range vals {
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if v != "" {
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return v
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}
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}
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return ""
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}
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// LengthKm 计算轨迹里程（Haversine）。
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func (t Track) LengthKm() float64 {
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sum := 0.0
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for i := 1; i < len(t.Points); i++ {
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sum += haversine(t.Points[i-1], t.Points[i])
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}
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return sum
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}
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// BBox 返回 [minLon, minLat, maxLon, maxLat]。
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func (t Track) BBox() [4]float64 {
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b := [4]float64{180, 90, -180, -90}
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for _, p := range t.Points {
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if p.Lon < b[0] {
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b[0] = p.Lon
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}
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if p.Lat < b[1] {
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b[1] = p.Lat
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}
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if p.Lon > b[2] {
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b[2] = p.Lon
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}
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if p.Lat > b[3] {
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b[3] = p.Lat
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}
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}
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return b
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}
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func haversine(a, b Point) float64 {
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const r = 6371.0
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dLat := (b.Lat - a.Lat) * math.Pi / 180
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dLon := (b.Lon - a.Lon) * math.Pi / 180
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la1 := a.Lat * math.Pi / 180
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la2 := b.Lat * math.Pi / 180
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h := math.Sin(dLat/2)*math.Sin(dLat/2) +
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math.Cos(la1)*math.Cos(la2)*math.Sin(dLon/2)*math.Sin(dLon/2)
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return 2 * r * math.Asin(math.Sqrt(h))
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}
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