/**
* Requires vn to point to a relation element. From there it iterates over all matches of the ap.
* Puts an empty list for each referenced way.
*/
private List<Tuple2<WayRole, Long>> extractWayRefs(VTDNav vn, Hashtable<Long, List<Long>> ways)
throws NavException, XPathEvalException {
vn.push();
List<Tuple2<WayRole, Long>> refs = new ArrayList<>();
for (int j = MEMBER_WAY_PATH.evalXPath(); j != -1; j = MEMBER_WAY_PATH.evalXPath()) {
long ref = Long.parseLong(vn.toString(vn.getAttrVal("ref")));
String roleAsString = vn.toString(vn.getAttrVal("role")).toLowerCase();
WayRole role;
switch (roleAsString) {
case "inner":
role = WayRole.INNER;
break;
case "outer":
role = WayRole.OUTER;
break;
default:
continue;
}
refs.add(Tuple.tuple(role, ref));
ways.put(ref, Collections.emptyList());
}
MEMBER_WAY_PATH.resetXPath();
vn.pop();
return refs;
}
private void extractReferencedWays(
VTDNav vn, Hashtable<Long, List<Long>> ways, Hashtable<Long, Point2D> nodes)
throws XPathEvalException, NavException {
vn.push();
for (int i = WAY_PATH.evalXPath(); i != -1; i = WAY_PATH.evalXPath()) {
long id = Long.parseLong(vn.toString(vn.getAttrVal("id")));
// By checking that we already referenced the id we can reduce memory pressure
if (ways.containsKey(id)) {
ways.put(id, extractNodeRefs(vn, nodes));
}
}
vn.pop();
}
/**
* Requires vn to point to a way element. From there it iterates over all matches of the ap. Puts
* a dummy point into nodes for every node it finds.
*/
private List<Long> extractNodeRefs(VTDNav vn, Hashtable<Long, Point2D> nodes)
throws NavException, XPathEvalException {
vn.push();
List<Long> refs = new ArrayList<>();
for (int j = NODE_REF_PATH.evalXPath(); j != -1; j = NODE_REF_PATH.evalXPath()) {
long ref = Long.parseLong(vn.toString(j + 1));
refs.add(ref);
nodes.put(ref, new Point2D(0, 0));
}
NODE_REF_PATH.resetXPath();
vn.pop();
return refs;
}
private List<List<Long>> extractWaysOfBuildings(VTDNav vn, Hashtable<Long, Point2D> nodes)
throws XPathEvalException, NavException {
vn.push();
List<List<Long>> ways = new ArrayList<>();
for (int i = BUILDING_WAY_PATH.evalXPath(); i != -1; i = BUILDING_WAY_PATH.evalXPath()) {
// The lambda will put in a dummy value for each encountered node,
// so that we know later which nodes we need to parse.
ways.add(extractNodeRefs(vn, nodes));
}
vn.pop();
BUILDING_WAY_PATH.resetXPath();
return ways;
}
private List<List<Tuple2<WayRole, Long>>> extractWayRefsOfMultipolygons(
VTDNav vn, Hashtable<Long, List<Long>> ways) throws NavException, XPathEvalException {
vn.push();
List<List<Tuple2<WayRole, Long>>> multipolygons = new ArrayList<>();
for (int i = BUILDING_MULTIPOLYGON_PATH.evalXPath();
i != -1;
i = BUILDING_MULTIPOLYGON_PATH.evalXPath()) {
// For an explanation for the lambda see extractWaysOfBuildings
multipolygons.add(extractWayRefs(vn, ways));
}
vn.pop();
BUILDING_WAY_PATH.resetXPath();
return multipolygons;
}
private void extractReferencedNodes(VTDNav vn, Hashtable<Long, Point2D> nodes)
throws XPathEvalException, NavException {
vn.push();
for (int i = NODE_PATH.evalXPath(); i != -1; i = NODE_PATH.evalXPath()) {
long id = Long.parseLong(vn.toString(vn.getAttrVal("id")));
// By checking that we already referenced the id we can reduce memory pressure
if (nodes.containsKey(id)) {
nodes.put(
id,
new Point2D(
Double.parseDouble(vn.toString(vn.getAttrVal("lon"))) * (1 << 10),
Double.parseDouble(vn.toString(vn.getAttrVal("lat"))) * (1 << 10)));
}
}
// Make sure we have all referenced nodes extracted
// assert !nodes.containsValue(DUMMY_POINT);
vn.pop();
}
public OSMGeometryParser() {
try {
NODE_PATH.selectXPath("/osm/node");
NODE_REF_PATH.selectXPath("nd/@ref");
BUILDING_WAY_PATH.selectXPath("/osm/way[./tag[@k='building']]");
BUILDING_MULTIPOLYGON_PATH.selectXPath(
"/osm/relation[./tag[@k='type' and @v='multipolygon'] and ./tag/@k='building']");
MEMBER_WAY_PATH.selectXPath("member[@type='way']");
WAY_PATH.selectXPath("/osm/way");
} catch (XPathParseException e) {
e.printStackTrace();
}
}
public List<Triangle> parseFile(InputStream is) {
try {
VTDGen vg = new VTDGen();
vg.setDoc(IOUtils.toByteArray(is));
vg.parse(false);
VTDNav vn = vg.getNav();
NODE_PATH.resetXPath();
NODE_PATH.bind(vn); // This is important state for the later method calls!
NODE_REF_PATH.resetXPath();
NODE_REF_PATH.bind(vn);
BUILDING_WAY_PATH.resetXPath();
BUILDING_WAY_PATH.bind(vn);
BUILDING_MULTIPOLYGON_PATH.resetXPath();
BUILDING_MULTIPOLYGON_PATH.bind(vn);
MEMBER_WAY_PATH.resetXPath();
MEMBER_WAY_PATH.bind(vn);
WAY_PATH.resetXPath();
WAY_PATH.bind(vn);
// A hash from node ids to actual node positions
Hashtable<Long, Point2D> nodes = new Hashtable<>();
// A hash from way refs referenced from multipolygons to their actual list of node refs
Hashtable<Long, List<Long>> multipolygonWays = new Hashtable<>();
// The following call initializes accessed node refs in nodes to a dummy value.
List<List<Long>> buildingWays = extractWaysOfBuildings(vn, nodes);
// The following call initializes accessed way refs from multipolygons to a dummy value.
List<List<Tuple2<WayRole, Long>>> multipolygonWayRefs =
extractWayRefsOfMultipolygons(vn, multipolygonWays);
// This will extract all referenced multipolygon multipolygonWays, excluding the building
// multipolygonWays
// Also adds referenced nodes to nodes
extractReferencedWays(vn, multipolygonWays, nodes);
// This will extract all referenced nodes, but no more.
extractReferencedNodes(vn, nodes);
// Finally build the polygon list by following the node refs in wayRefs.
// Triangulate each polygon and return the flattened list of triangles.
// This way, poly2tri's types will not leak out of this class and we operate
// on triangles anyway.
return buildPolygons(nodes, buildingWays, multipolygonWays, multipolygonWayRefs)
.flatMap(
p -> {
try {
p.ComplexToSimplePolygon();
EarClipping ec = new EarClipping(p.SimplePolygon);
return ec.Triangulation().stream();
} catch (RuntimeException ignored) {
}
return Stream.empty();
})
.toList();
} catch (XPathEvalException | NavException | IOException | ParseException e) {
e.printStackTrace();
return new ArrayList<>();
}
}