source: osm/applications/editors/josm/plugins/seachart/src/s57/S57map.java@ 30996

Last change on this file since 30996 was 30996, checked in by malcolmh, 11 years ago

Catch invalid nodes

File size: 19.8 KB
Line 
1/* Copyright 2014 Malcolm Herring
2 *
3 * This is free software: you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation, version 3 of the License.
6 *
7 * For a copy of the GNU General Public License, see <http://www.gnu.org/licenses/>.
8 */
9
10package s57;
11
12import java.util.*;
13
14import s57.S57obj;
15import s57.S57obj.*;
16import s57.S57att;
17import s57.S57att.*;
18import s57.S57val;
19import s57.S57val.*;
20
21public class S57map {
22
23 public class MapBounds {
24 public double minlat;
25 public double minlon;
26 public double maxlat;
27 public double maxlon;
28 public MapBounds() {
29 minlat = 90;
30 minlon = 180;
31 maxlat = -90;
32 maxlon = -180;
33 }
34 }
35
36 public enum Nflag {
37 ANON, // Edge inner nodes
38 ISOL, // Node not part of Edge
39 CONN, // Edge first and last nodes
40 DPTH // Sounding nodes
41 }
42
43 public class Snode { // All coordinates in map
44 public double lat; // Latitude
45 public double lon; // Longitude
46 public Nflag flg; // Role of node
47
48 public Snode() {
49 flg = Nflag.ANON;
50 lat = 0;
51 lon = 0;
52 }
53 public Snode(double ilat, double ilon) {
54 flg = Nflag.ANON;
55 lat = ilat;
56 lon = ilon;
57 }
58 public Snode(double ilat, double ilon, Nflag iflg) {
59 lat = ilat;
60 lon = ilon;
61 flg = iflg;
62 }
63 }
64
65 public class Dnode extends Snode { // All depth soundings
66 public double val; // Sounding value
67
68 public Dnode() {
69 flg = Nflag.DPTH;
70 lat = 0;
71 lon = 0;
72 val = 0;
73 }
74 public Dnode(double ilat, double ilon, double ival) {
75 flg = Nflag.DPTH;
76 lat = ilat;
77 lon = ilon;
78 val = ival;
79 }
80 }
81
82 public class Edge { // A polyline segment
83 public long first; // First CONN node
84 public long last; // Last CONN node
85 public ArrayList<Long> nodes; // Inner ANON nodes
86
87 public Edge() {
88 first = 0;
89 last = 0;
90 nodes = new ArrayList<Long>();
91 }
92 }
93
94 public enum Rflag {
95 UNKN, MASTER, SLAVE
96 }
97
98 public class Reln {
99 public long id;
100 public Rflag reln;
101 public Reln(long i, Rflag r) {
102 id = i;
103 reln = r;
104 }
105 }
106
107 public class RelTab extends ArrayList<Reln> {
108 public RelTab() {
109 super();
110 }
111 }
112
113 public class ObjTab extends HashMap<Integer, AttMap> {
114 public ObjTab() {
115 super();
116 }
117 }
118
119 public class ObjMap extends EnumMap<Obj, ObjTab> {
120 public ObjMap() {
121 super(Obj.class);
122 }
123 }
124
125 public class AttMap extends HashMap<Att, AttVal<?>> {
126 public AttMap() {
127 super();
128 }
129 }
130
131 public class NodeTab extends HashMap<Long, Snode> {
132 public NodeTab() {
133 super();
134 }
135 }
136
137 public class EdgeTab extends HashMap<Long, Edge> {
138 public EdgeTab() {
139 super();
140 }
141 }
142
143 public class FtrMap extends EnumMap<Obj, ArrayList<Feature>> {
144 public FtrMap() {
145 super(Obj.class);
146 }
147 }
148
149 public class FtrTab extends HashMap<Long, Feature> {
150 public FtrTab() {
151 super();
152 }
153 }
154
155 public class Prim { // Spatial element
156 public long id; // Snode ID for POINTs, Edge ID for LINEs & AREAs)
157 public boolean forward; // Direction of vector used (LINEs & AREAs)
158 public boolean outer; // Exterior/Interior boundary (AREAs)
159 public Prim() {
160 id = 0; forward = true; outer = true;
161 }
162 public Prim(long i) {
163 id = i; forward = true; outer = true;
164 }
165 public Prim(long i, boolean o) {
166 id = i; forward = true; outer = o;
167 }
168 public Prim(long i, boolean f, boolean o) {
169 id = i; forward = f; outer = o;
170 }
171 }
172
173 public class Comp { // Composite spatial element
174 public long ref; // ID of Comp
175 public int size; // Number of Prims in this Comp
176 public Comp(long r, int s) {
177 ref = r;
178 size = s;
179 }
180 }
181
182 public enum Pflag {
183 NOSP, POINT, LINE, AREA
184 }
185
186 public class Geom { // Geometric structure of feature
187 public Pflag prim; // Geometry type
188 public ArrayList<Prim> elems; // Ordered list of elements
189 public int outers; // Number of outers
190 public int inners; // Number of inners
191 public ArrayList<Comp> refs; // Ordered list of compounds
192 public double area; // Area of feature
193 public double length; // Length of feature
194 public Snode centre; // Centre of feature
195 public Geom(Pflag p) {
196 prim = p;
197 elems = new ArrayList<Prim>();
198 outers = inners = 0;
199 refs = new ArrayList<Comp>();
200 area = 0;
201 length = 0;
202 centre = new Snode();
203 }
204 }
205
206 public class Feature {
207 public Rflag reln; // Relationship status
208 public Geom geom; // Geometry data
209 public Obj type; // Feature type
210 public AttMap atts; // Feature attributes
211 public RelTab rels; // Related objects
212 public ObjMap objs; // Slave object attributes
213
214 Feature() {
215 reln = Rflag.UNKN;
216 geom = new Geom(Pflag.NOSP);
217 type = Obj.UNKOBJ;
218 atts = new AttMap();
219 rels = new RelTab();
220 objs = new ObjMap();
221 }
222 }
223
224 public NodeTab nodes;
225 public EdgeTab edges;
226
227 public FtrMap features;
228 public FtrTab index;
229
230 public long ref;
231 private Feature feature;
232 private Edge edge;
233
234 public S57map() {
235 nodes = new NodeTab(); // All nodes in map
236 edges = new EdgeTab(); // All edges in map
237 feature = new Feature(); // Current feature being built
238 features = new FtrMap(); // All features in map, grouped by type
239 index = new FtrTab(); // Feature look-up table
240 ref = 0x0000ffffffff0000L;// Compound reference generator
241 }
242
243 // S57 map building methods
244
245 public void newNode(long id, double lat, double lon, Nflag flag) {
246 nodes.put(id, new Snode(Math.toRadians(lat), Math.toRadians(lon), flag));
247 if (flag == Nflag.ANON) {
248 edge.nodes.add(id);
249 }
250 }
251
252 public void newNode(long id, double lat, double lon, double depth) {
253 nodes.put(id, new Dnode(Math.toRadians(lat), Math.toRadians(lon), depth));
254 }
255
256 public void newFeature(long id, Pflag p, long objl) {
257 feature = new Feature();
258 Obj obj = S57obj.decodeType(objl);
259 if (obj == Obj.BCNWTW)
260 obj = Obj.BCNLAT;
261 if (obj == Obj.BOYWTW)
262 obj = Obj.BOYLAT;
263 if (obj == Obj.C_AGGR)
264 feature.reln = Rflag.UNKN;
265 feature.geom = new Geom(p);
266 feature.type = obj;
267 if (obj != Obj.UNKOBJ) {
268 index.put(id, feature);
269 }
270 }
271
272 public void newObj(long id, int rind) {
273 Rflag r = Rflag.UNKN;
274 switch (rind) {
275 case 1:
276 r = Rflag.MASTER;
277 break;
278 case 2:
279 r = Rflag.SLAVE;
280 break;
281 case 3:
282 r = Rflag.UNKN;
283 break;
284 }
285 feature.rels.add(new Reln(id, r));
286 }
287
288 public void endFeature() {
289
290 }
291
292 public void newAtt(long attl, String atvl) {
293 Att att = S57att.decodeAttribute(attl);
294 AttVal<?> val = S57val.decodeValue(atvl, att);
295 feature.atts.put(att, val);
296 }
297
298 public void newPrim(long id, long ornt, long usag) {
299 feature.geom.elems.add(new Prim(id, (ornt != 2), (usag != 2)));
300 }
301
302 public void addConn(long id, int topi) {
303 if (topi == 1) {
304 edge.first = id;
305 } else {
306 edge.last = id;
307 }
308 }
309
310 public void newEdge(long id) {
311 edge = new Edge();
312 edges.put(id, edge);
313 }
314
315 public void endFile() {
316 for (long id : index.keySet()) {
317 Feature feature = index.get(id);
318 sortGeom(feature);
319 for (Reln reln : feature.rels) {
320 Feature rel = index.get(reln.id);
321 if (cmpGeoms(feature.geom, rel.geom)) {
322 switch (reln.reln) {
323 case SLAVE:
324 feature.reln = Rflag.MASTER;
325 break;
326 default:
327 feature.reln = Rflag.UNKN;
328 break;
329 }
330 rel.reln = reln.reln;
331 } else {
332 reln.reln = Rflag.UNKN;
333 }
334 }
335 }
336 for (long id : index.keySet()) {
337 Feature feature = index.get(id);
338 if (feature.reln == Rflag.UNKN) {
339 feature.reln = Rflag.MASTER;
340 }
341 if ((feature.type != Obj.UNKOBJ) && (feature.reln == Rflag.MASTER)) {
342 if (features.get(feature.type) == null) {
343 features.put(feature.type, new ArrayList<Feature>());
344 }
345 features.get(feature.type).add(feature);
346 }
347 }
348 for (long id : index.keySet()) {
349 Feature feature = index.get(id);
350 for (Reln reln : feature.rels) {
351 Feature rel = index.get(reln.id);
352 if (rel.reln == Rflag.SLAVE) {
353 if (feature.objs.get(rel.type) == null) {
354 feature.objs.put(rel.type, new ObjTab());
355 }
356 ObjTab tab = feature.objs.get(rel.type);
357 int ix = tab.size();
358 tab.put(ix, rel.atts);
359 }
360 }
361 }
362 }
363
364 // OSM map building methods
365
366 public void addNode(long id, double lat, double lon) {
367 Snode node = new Snode(Math.toRadians(lat), Math.toRadians(lon));
368 nodes.put(id, node);
369 feature = new Feature();
370 feature.reln = Rflag.UNKN;
371 feature.geom.prim = Pflag.POINT;
372 feature.geom.elems.add(new Prim(id));
373 edge = null;
374 }
375
376 public void addEdge(long id) {
377 feature = new Feature();
378 feature.reln = Rflag.UNKN;
379 feature.geom.prim = Pflag.LINE;
380 feature.geom.elems.add(new Prim(id));
381 edge = new Edge();
382 }
383
384 public void addToEdge(long node) {
385 if (edge.first == 0) {
386 edge.first = node;
387 nodes.get(node).flg = Nflag.CONN;
388 } else {
389 if (edge.last != 0) {
390 edge.nodes.add(edge.last);
391 }
392 edge.last = node;
393 }
394 }
395
396 public void addArea(long id) {
397 feature = new Feature();
398 feature.reln = Rflag.UNKN;
399 feature.geom.prim = Pflag.AREA;
400 edge = null;
401 }
402
403 public void addToArea(long id, boolean outer) {
404 feature.geom.elems.add(new Prim(id, outer));
405 }
406
407 public void addTag(String key, String val) {
408 feature.reln = Rflag.MASTER;
409 String subkeys[] = key.split(":");
410 if ((subkeys.length > 1) && subkeys[0].equals("seamark")) {
411 Obj obj = S57obj.enumType(subkeys[1]);
412 if ((subkeys.length > 2) && (obj != Obj.UNKOBJ)) {
413 int idx = 0;
414 Att att = Att.UNKATT;
415 try {
416 idx = Integer.parseInt(subkeys[2]);
417 if (subkeys.length == 4) {
418 att = s57.S57att.enumAttribute(subkeys[3], obj);
419 }
420 } catch (Exception e) {
421 att = S57att.enumAttribute(subkeys[2], obj);
422 }
423 ObjTab objs = feature.objs.get(obj);
424 if (objs == null) {
425 objs = new ObjTab();
426 feature.objs.put(obj, objs);
427 }
428 AttMap atts = objs.get(idx);
429 if (atts == null) {
430 atts = new AttMap();
431 objs.put(idx, atts);
432 }
433 AttVal<?> attval = S57val.convertValue(val, att);
434 if (attval.val != null)
435 atts.put(att, attval);
436 } else {
437 if (subkeys[1].equals("type")) {
438 obj = S57obj.enumType(val);
439 feature.type = obj;
440 ObjTab objs = feature.objs.get(obj);
441 if (objs == null) {
442 objs = new ObjTab();
443 feature.objs.put(obj, objs);
444 }
445 AttMap atts = objs.get(0);
446 if (atts == null) {
447 atts = new AttMap();
448 objs.put(0, atts);
449 }
450 } else {
451 Att att = S57att.enumAttribute(subkeys[1], Obj.UNKOBJ);
452 if (att != Att.UNKATT) {
453 AttVal<?> attval = S57val.convertValue(val, att);
454 if (attval.val != null)
455 feature.atts.put(att, attval);
456 }
457 }
458 }
459 }
460 }
461
462 public void tagsDone(long id) {
463 switch (feature.geom.prim) {
464 case POINT:
465 Snode node = nodes.get(id);
466 if (node.flg != Nflag.CONN) {
467 node.flg = Nflag.ISOL;
468 }
469 break;
470 case LINE:
471 edges.put(id, edge);
472 nodes.get(edge.first).flg = Nflag.CONN;
473 nodes.get(edge.last).flg = Nflag.CONN;
474 if (edge.first == edge.last) {
475 feature.geom.prim = Pflag.AREA;
476 }
477 break;
478 case AREA:
479 break;
480 default:
481 break;
482 }
483 if ((sortGeom(feature)) && (feature.type != Obj.UNKOBJ) && !((edge != null) && (edge.last == 0))) {
484 index.put(id, feature);
485 if (features.get(feature.type) == null) {
486 features.put(feature.type, new ArrayList<Feature>());
487 }
488 features.get(feature.type).add(feature);
489 feature.geom.centre = findCentroid(feature);
490 }
491 }
492
493 // Utility methods
494
495 public boolean sortGeom(Feature feature) {
496 Geom sort = new Geom(feature.geom.prim);
497 long first = 0;
498 long last = 0;
499 Comp comp = null;
500 boolean next = true;
501 feature.geom.length = 0;
502 feature.geom.area = 0;
503 if (feature.geom.prim == Pflag.POINT) {
504 return true;
505 } else {
506 int sweep = feature.geom.elems.size();
507 while (!feature.geom.elems.isEmpty()) {
508 Prim prim = feature.geom.elems.remove(0);
509 Edge edge = edges.get(prim.id);
510 if (edge == null) {
511 return false;
512 }
513 if (next == true) {
514 next = false;
515 if (prim.forward) {
516 first = edge.first;
517 last = edge.last;
518 } else {
519 first = edge.last;
520 last = edge.first;
521 }
522 sort.elems.add(prim);
523 if (prim.outer) {
524 sort.outers++;
525 } else {
526 sort.inners++;
527 }
528 comp = new Comp(ref++, 1);
529 sort.refs.add(comp);
530 } else {
531 if (prim.forward) {
532 if (edge.first == last) {
533 sort.elems.add(prim);
534 last = edge.last;
535 comp.size++;
536 } else if (edge.last == first) {
537 sort.elems.add(0, prim);
538 first = edge.first;
539 comp.size++;
540 } else {
541 feature.geom.elems.add(prim);
542 }
543 } else {
544 if (edge.last == last) {
545 sort.elems.add(prim);
546 last = edge.first;
547 comp.size++;
548 } else if (edge.first == first) {
549 sort.elems.add(0, prim);
550 first = edge.last;
551 comp.size++;
552 } else {
553 feature.geom.elems.add(prim);
554 }
555 }
556 }
557 if (--sweep == 0) {
558 next = true;
559 sweep = feature.geom.elems.size();
560 }
561 }
562 if ((sort.prim == Pflag.LINE) && (sort.outers == 1) && (sort.inners == 0) && (first == last)) {
563 sort.prim = Pflag.AREA;
564 }
565 feature.geom = sort;
566 }
567 if (feature.geom.prim == Pflag.AREA) {
568 ArrayList<Prim> outers = new ArrayList<Prim>();
569 ArrayList<Prim> inners = new ArrayList<Prim>();
570 for (Prim prim : feature.geom.elems) {
571 if (prim.outer) {
572 outers.add(prim);
573 } else {
574 inners.add(prim);
575 }
576 }
577 ArrayList<Prim> sorting = outers.size() > 0 ? outers : inners;
578 ArrayList<Prim> closed = null;
579 sort = new Geom(feature.geom.prim);
580 sort.outers = feature.geom.outers;
581 sort.inners = feature.geom.inners;
582 sort.refs = feature.geom.refs;
583 next = true;
584 while (!sorting.isEmpty()) {
585 Prim prim = sorting.remove(0);
586 Edge edge = edges.get(prim.id);
587 if (next == true) {
588 next = false;
589 closed = new ArrayList<Prim>();
590 closed.add(prim);
591 if (prim.forward) {
592 first = edge.first;
593 last = edge.last;
594 } else {
595 first = edge.last;
596 last = edge.first;
597 }
598 } else {
599 if (prim.forward) {
600 if (edge.first == last) {
601 last = edge.last;
602 closed.add(prim);
603 } else {
604 sorting.add(0, prim);
605 next = true;
606 }
607 } else {
608 if (edge.last == last) {
609 last = edge.first;
610 closed.add(prim);
611 } else {
612 sorting.add(0, prim);
613 next = true;
614 }
615 }
616 }
617 if (first == last) {
618 sort.elems.addAll(closed);
619 next = true;
620 }
621 if (sorting.isEmpty() && sorting == outers) {
622 sorting = inners;
623 next = true;
624 }
625 }
626 feature.geom = sort;
627 }
628 feature.geom.length = calcLength(feature.geom);
629 feature.geom.area = calcArea(feature.geom);
630 return true;
631 }
632
633 public boolean cmpGeoms (Geom g1, Geom g2) {
634 return ((g1.prim == g2.prim) && (g1.outers == g2.outers) && (g1.inners == g2.inners) && (g1.elems.size() == g2.elems.size()));
635 }
636
637 public class EdgeIterator {
638 Edge edge;
639 boolean forward;
640 ListIterator<Long> it;
641
642 public EdgeIterator(Edge e, boolean dir) {
643 edge = e;
644 forward = dir;
645 it = null;
646 }
647
648 public boolean hasNext() {
649 return (edge != null);
650 }
651
652 public long nextRef() {
653 long ref = 0;
654 if (forward) {
655 if (it == null) {
656 ref = edge.first;
657 it = edge.nodes.listIterator();
658 } else {
659 if (it.hasNext()) {
660 ref = it.next();
661 } else {
662 ref = edge.last;
663 edge = null;
664 }
665 }
666 } else {
667 if (it == null) {
668 ref = edge.last;
669 it = edge.nodes.listIterator(edge.nodes.size());
670 } else {
671 if (it.hasPrevious()) {
672 ref = it.previous();
673 } else {
674 ref = edge.first;
675 edge = null;
676 }
677 }
678 }
679 return ref;
680 }
681
682 public Snode next() {
683 return nodes.get(nextRef());
684 }
685 }
686
687 public class GeomIterator {
688 Geom geom;
689 Prim prim;
690 EdgeIterator eit;
691 ListIterator<S57map.Prim> ite;
692 ListIterator<Comp> itc;
693 Comp comp;
694 int ec;
695 long lastref;
696
697 public GeomIterator(Geom g) {
698 geom = g;
699 lastref = 0;
700 ite = geom.elems.listIterator();
701 itc = geom.refs.listIterator();
702 }
703
704 public boolean hasComp() {
705 return (itc.hasNext());
706 }
707
708 public long nextComp() {
709 comp = itc.next();
710 ec = comp.size;
711 lastref = 0;
712 return comp.ref;
713 }
714
715 public boolean hasEdge() {
716 return (ec > 0) && ite.hasNext();
717 }
718
719 public long nextEdge() {
720 prim = ite.next();
721 eit = new EdgeIterator(edges.get(prim.id), prim.forward);
722 ec--;
723 return prim.id;
724 }
725
726 public boolean hasNode() {
727 return (eit.hasNext());
728 }
729
730 public long nextRef(boolean all) {
731 long ref = eit.nextRef();
732 if (!all && (ref == lastref)) {
733 ref = eit.nextRef();
734 }
735 lastref = ref;
736 return ref;
737 }
738
739 public long nextRef() {
740 return nextRef(false);
741 }
742
743 public Snode next() {
744 return nodes.get(nextRef());
745 }
746 }
747
748 double signedArea(Geom geom) {
749 Snode node;
750 double lat, lon, llon, llat;
751 lat = lon = llon = llat = 0;
752 double sigma = 0;
753 GeomIterator git = new GeomIterator(geom);
754 if (git.hasComp()) {
755 git.nextComp();
756 while (git.hasEdge()) {
757 git.nextEdge();
758 while (git.hasNode()) {
759 node = git.next();
760 if (node != null) {
761 llon = lon;
762 llat = lat;
763 lat = node.lat;
764 lon = node.lon;
765 sigma += (lon * Math.sin(llat)) - (llon * Math.sin(lat));
766 }
767 }
768 }
769 }
770 return sigma / 2.0;
771 }
772
773 public boolean handOfArea(Geom geom) {
774 return (signedArea(geom) < 0);
775 }
776
777 public double calcArea(Geom geom) {
778 return Math.abs(signedArea(geom)) * 3444 * 3444;
779 }
780
781 public double calcLength(Geom geom) {
782 Snode node;
783 double lat, lon, llon, llat;
784 lat = lon = llon = llat = 0;
785 double sigma = 0;
786 boolean first = true;
787 GeomIterator git = new GeomIterator(geom);
788 while (git.hasComp()) {
789 git.nextComp();
790 while (git.hasEdge()) {
791 git.nextEdge();
792 while (git.hasNode()) {
793 node = git.next();
794 if (first) {
795 first = false;
796 lat = node.lat;
797 lon = node.lon;
798 } else if (node != null) {
799 llat = lat;
800 llon = lon;
801 lat = node.lat;
802 lon = node.lon;
803 sigma += Math.acos(Math.sin(lat) * Math.sin(llat) + Math.cos(lat) * Math.cos(llat) * Math.cos(llon - lon));
804 }
805 }
806 }
807 }
808 return sigma * 3444;
809 }
810
811 public Snode findCentroid(Feature feature) {
812 double lat, lon, slat, slon, llat, llon;
813 llat = llon = lat = lon = slat = slon = 0;
814 double sarc = 0;
815 boolean first = true;
816 switch (feature.geom.prim) {
817 case POINT:
818 return nodes.get(feature.geom.elems.get(0).id);
819 case LINE:
820 GeomIterator git = new GeomIterator(feature.geom);
821 while (git.hasComp()) {
822 git.nextComp();
823 while (git.hasEdge()) {
824 git.nextEdge();
825 while (git.hasNode()) {
826 Snode node = git.next();
827 lat = node.lat;
828 lon = node.lon;
829 if (first) {
830 first = false;
831 } else {
832 sarc += (Math.acos(Math.cos(lon - llon) * Math.cos(lat - llat)));
833 }
834 llat = lat;
835 llon = lon;
836 }
837 }
838 }
839 double harc = sarc / 2;
840 sarc = 0;
841 first = true;
842 git = new GeomIterator(feature.geom);
843 while (git.hasComp()) {
844 git.nextComp();
845 while (git.hasEdge()) {
846 git.nextEdge();
847 while (git.hasNode()) {
848 Snode node = git.next();
849 lat = node.lat;
850 lon = node.lon;
851 if (first) {
852 first = false;
853 } else {
854 sarc = (Math.acos(Math.cos(lon - llon) * Math.cos(lat - llat)));
855 if (sarc > harc)
856 break;
857 }
858 harc -= sarc;
859 llat = lat;
860 llon = lon;
861 }
862 }
863 }
864 return new Snode(llat + ((lat - llat) * harc / sarc), llon + ((lon - llon) * harc / sarc));
865 case AREA:
866 git = new GeomIterator(feature.geom);
867 while (git.hasComp()) {
868 git.nextComp();
869 while (git.hasEdge()) {
870 git.nextEdge();
871 while (git.hasNode()) {
872 Snode node = git.next();
873 lat = node.lat;
874 lon = node.lon;
875 if (first) {
876 first = false;
877 } else {
878 double arc = (Math.acos(Math.cos(lon - llon) * Math.cos(lat - llat)));
879 slat += ((lat + llat) / 2 * arc);
880 slon += ((lon + llon) / 2 * arc);
881 sarc += arc;
882 }
883 llon = lon;
884 llat = lat;
885 }
886 }
887 }
888 return new Snode((sarc > 0.0 ? slat / sarc : 0.0), (sarc > 0.0 ? slon / sarc : 0.0));
889 default:
890 }
891 return null;
892 }
893
894}
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