Mercurial > gemma
view pkg/octree/tin.go @ 968:a4fe07a21ba7
Moved octree builder into octree package to be reusable by the sounding result import job.
author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
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date | Wed, 17 Oct 2018 16:00:49 +0200 |
parents | |
children | f9fb6c399f3f |
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package octree import ( "bytes" "encoding/binary" "errors" "fmt" "io" "log" "math" ) var ( errNoByteSlice = errors.New("Not a byte slice") errTooLessPoints = errors.New("Too less points") ) const wgs84 = 4326 type Tin struct { EPSG uint32 Vertices []Vertex Triangles [][]int32 Min Vertex Max Vertex } func (t *Tin) FromWKB(data []byte) error { log.Printf("data length %d\n", len(data)) r := bytes.NewReader(data) endian, err := r.ReadByte() var order binary.ByteOrder switch { case err != nil: return err case endian == wkbNDR: order = binary.LittleEndian case endian == wkbXDR: order = binary.BigEndian default: return fmt.Errorf("unknown byte order %x", endian) } var geomType uint32 err = binary.Read(r, order, &geomType) switch { case err != nil: return err case geomType != wkbTinZ: return fmt.Errorf("unknown geometry type %x", geomType) } var num uint32 if err = binary.Read(r, order, &num); err != nil { return err } vertices := make([]Vertex, 0, 100000) var v Vertex v2i := make(map[Vertex]int32, 100000) var indexPool []int32 allocIndices := func() []int32 { if len(indexPool) == 0 { indexPool = make([]int32, 3*8*1024) } ids := indexPool[:3] indexPool = indexPool[3:] return ids } var triangles [][]int32 min := Vertex{math.MaxFloat64, math.MaxFloat64, math.MaxFloat64} max := Vertex{-math.MaxFloat64, -math.MaxFloat64, -math.MaxFloat64} for i := uint32(0); i < num; i++ { endian, err = r.ReadByte() switch { case err != nil: return err case endian == wkbNDR: order = binary.LittleEndian case endian == wkbXDR: order = binary.BigEndian default: return fmt.Errorf("unknown byte order %x", endian) } err = binary.Read(r, order, &geomType) switch { case err != nil: return err case geomType != wkbTriangleZ: return fmt.Errorf("unknown geometry type %d", geomType) } var rings uint32 if err = binary.Read(r, order, &rings); err != nil { return err } triangle := allocIndices() for ring := uint32(0); ring < rings; ring++ { var npoints uint32 if err = binary.Read(r, order, &npoints); err != nil { return err } if npoints < 3 { return errTooLessPoints } for p := uint32(0); p < npoints; p++ { var x, y, z uint64 for _, addr := range []*uint64{&x, &y, &z} { if err = binary.Read(r, order, addr); err != nil { return err } } if p >= 3 || ring >= 1 { // Don't store the forth point. continue } // Do this conversion later to spare reflect calls // and allocs in binary.Read. v.X = math.Float64frombits(x) v.Y = math.Float64frombits(y) v.Z = math.Float64frombits(z) idx, found := v2i[v] if !found { idx = int32(len(vertices)) v2i[v] = idx vertices = append(vertices, v) min.Minimize(v) max.Maximize(v) } triangle[p] = idx } } triangles = append(triangles, triangle) } log.Printf("bbox: [[%f, %f], [%f, %f]]\n", min.X, min.Y, max.X, max.Y) *t = Tin{ EPSG: wgs84, Vertices: vertices, Triangles: triangles, Min: min, Max: max, } return nil } func (t *Tin) Scan(raw interface{}) error { data, ok := raw.([]byte) if !ok { return errNoByteSlice } return t.FromWKB(data) } func (t *Tin) Serialize(w io.Writer) error { if err := binary.Write(w, binary.LittleEndian, t.EPSG); err != nil { return err } if err := t.Min.Write(w); err != nil { return err } if err := t.Max.Write(w); err != nil { return err } if err := binary.Write( w, binary.LittleEndian, uint32(len(t.Vertices))); err != nil { return err } for _, v := range t.Vertices { if err := v.Write(w); err != nil { return err } } log.Printf("vertices %d (%d)\n", len(t.Vertices), len(t.Vertices)*3*8) if err := binary.Write( w, binary.LittleEndian, uint32(len(t.Triangles))); err != nil { return err } var buf [binary.MaxVarintLen32]byte var written int var last int32 for _, triangle := range t.Triangles { for _, idx := range triangle { value := idx - last n := binary.PutVarint(buf[:], int64(value)) for p := buf[:n]; len(p) > 0; p = p[n:] { var err error if n, err = w.Write(p); err != nil { return err } written += n } last = idx } } log.Printf("compressed tin indices in bytes: %d (%d)\n", written, 3*4*len(t.Triangles)) return nil }