150 lines
2.9 KiB
Go
150 lines
2.9 KiB
Go
package geom
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import (
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"errors"
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"math"
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"github.com/omniscale/imposm3/element"
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"github.com/omniscale/imposm3/geom/geos"
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)
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type GeomError struct {
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message string
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level int
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}
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type Geometry struct {
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Geom *geos.Geom
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Wkb []byte
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}
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func (e *GeomError) Error() string {
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return e.message
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}
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func (e *GeomError) Level() int {
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return e.level
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}
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func newGeomError(message string, level int) *GeomError {
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return &GeomError{message, level}
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}
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var (
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ErrorOneNodeWay = newGeomError("need at least two separate nodes for way", 0)
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ErrorNoRing = newGeomError("linestrings do not form ring", 0)
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)
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func Point(g *geos.Geos, node element.Node) (*geos.Geom, error) {
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geom := g.Point(node.Long, node.Lat)
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if geom == nil {
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return nil, newGeomError("couldn't create point", 1)
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}
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g.DestroyLater(geom)
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return geom, nil
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}
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func nodesEqual(a, b element.Node) bool {
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if d := a.Long - b.Long; math.Abs(d) < 1e-9 {
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if d := a.Lat - b.Lat; math.Abs(d) < 1e-9 {
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return true
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}
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}
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return false
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}
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func unduplicateNodes(nodes []element.Node) []element.Node {
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if len(nodes) < 2 {
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return nodes
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}
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foundDup := false
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for i := 1; i < len(nodes); i++ {
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if nodesEqual(nodes[i-1], nodes[i]) {
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foundDup = true
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break
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}
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}
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if !foundDup {
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return nodes
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}
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result := make([]element.Node, 0, len(nodes))
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result = append(result, nodes[0])
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for i := 1; i < len(nodes); i++ {
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if nodesEqual(nodes[i-1], nodes[i]) {
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continue
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}
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result = append(result, nodes[i])
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}
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return result
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}
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func LineString(g *geos.Geos, nodes []element.Node) (*geos.Geom, error) {
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nodes = unduplicateNodes(nodes)
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if len(nodes) < 2 {
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return nil, ErrorOneNodeWay
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}
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coordSeq, err := g.CreateCoordSeq(uint32(len(nodes)), 2)
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if err != nil {
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return nil, err
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}
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// coordSeq inherited by LineString
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for i, nd := range nodes {
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coordSeq.SetXY(g, uint32(i), nd.Long, nd.Lat)
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}
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geom, err := coordSeq.AsLineString(g)
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if err != nil {
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// coordSeq gets Destroy by GEOS
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return nil, err
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}
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g.DestroyLater(geom)
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return geom, nil
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}
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func Polygon(g *geos.Geos, nodes []element.Node) (*geos.Geom, error) {
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nodes = unduplicateNodes(nodes)
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if len(nodes) < 4 {
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return nil, ErrorNoRing
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}
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coordSeq, err := g.CreateCoordSeq(uint32(len(nodes)), 2)
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if err != nil {
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return nil, err
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}
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// coordSeq inherited by LinearRing, no destroy
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for i, nd := range nodes {
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err := coordSeq.SetXY(g, uint32(i), nd.Long, nd.Lat)
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if err != nil {
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return nil, err
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}
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}
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ring, err := coordSeq.AsLinearRing(g)
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if err != nil {
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// coordSeq gets Destroy by GEOS
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return nil, err
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}
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// ring inherited by Polygon, no destroy
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geom := g.Polygon(ring, nil)
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if geom == nil {
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g.Destroy(ring)
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return nil, errors.New("unable to create polygon")
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}
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g.DestroyLater(geom)
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return geom, nil
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}
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func AsGeomElement(g *geos.Geos, geom *geos.Geom) (Geometry, error) {
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wkb := g.AsEwkbHex(geom)
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if wkb == nil {
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return Geometry{}, errors.New("could not create wkb")
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}
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return Geometry{
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Wkb: wkb,
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Geom: geom,
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}, nil
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}
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