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LUCENE-7204: Add check for backtracking over polygon path.

This commit is contained in:
Karl Wright 2016-04-12 15:37:13 -04:00
parent e034b04b06
commit 414bdea97a
2 changed files with 117 additions and 2 deletions
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79
lucene/spatial3d/src/java/org/apache/lucene/spatial3d/geom/GeoPolygonFactory.java
View File

@ -64,6 +64,7 @@ public class GeoPolygonFactory {
final List<GeoPolygon> holes) {
// The basic operation uses a set of points, two points determining one particular edge, and a sided plane
// describing membership.
//System.out.println("Initial point list = "+pointList+"; convexPointIndex = "+convexPointIndex+"; holes = "+holes);
final GeoCompositePolygon rval = new GeoCompositePolygon();
if (buildPolygonShape(rval,
planetModel, pointList, new BitSet(),
@ -391,6 +392,68 @@ public class GeoPolygonFactory {
// The edge buffer.
final EdgeBuffer edgeBuffer = new EdgeBuffer(pointsList, internalEdges, startPointIndex, endPointIndex, startingEdge);
/*
// Verify that the polygon does not self-intersect
// Now, look for non-adjacent edges that cross.
System.err.println("Looking for intersections...");
System.err.println("Starting edge is: "+startingEdge);
final Iterator<Edge> edgeIterator = edgeBuffer.iterator();
while (edgeIterator.hasNext()) {
final Edge edge = edgeIterator.next();
final Set<Edge> excludedEdges = new HashSet<>();
excludedEdges.add(edge);
Edge oneBoundary = edgeBuffer.getPrevious(edge);
while (oneBoundary.plane.isNumericallyIdentical(edge.plane)) {
excludedEdges.add(oneBoundary);
oneBoundary = edgeBuffer.getPrevious(oneBoundary);
}
excludedEdges.add(oneBoundary);
Edge otherBoundary = edgeBuffer.getNext(edge);
while (otherBoundary.plane.isNumericallyIdentical(edge.plane)) {
excludedEdges.add(otherBoundary);
otherBoundary = edgeBuffer.getNext(otherBoundary);
}
excludedEdges.add(otherBoundary);
// Now go through all other edges and rule out any intersections
final Iterator<Edge> compareIterator = edgeBuffer.iterator();
while (compareIterator.hasNext()) {
final Edge compareEdge = compareIterator.next();
if (!excludedEdges.contains(compareEdge)) {
// Found an edge we can compare with!
//System.err.println("Found a compare edge...");
boolean nonOverlapping = true;
// We need the other boundaries though.
Edge oneCompareBoundary = edgeBuffer.getPrevious(compareEdge);
while (oneCompareBoundary.plane.isNumericallyIdentical(compareEdge.plane)) {
if (excludedEdges.contains(oneCompareBoundary)) {
//System.err.println(" excluded because oneCompareBoundary found to be in set");
nonOverlapping = false;
break;
}
oneCompareBoundary = edgeBuffer.getPrevious(oneCompareBoundary);
}
Edge otherCompareBoundary = edgeBuffer.getNext(compareEdge);
while (otherCompareBoundary.plane.isNumericallyIdentical(compareEdge.plane)) {
if (excludedEdges.contains(otherCompareBoundary)) {
//System.err.println(" excluded because otherCompareBoundary found to be in set");
nonOverlapping = false;
break;
}
otherCompareBoundary = edgeBuffer.getNext(otherCompareBoundary);
}
if (nonOverlapping) {
//System.err.println("Preparing to call findIntersections...");
// Finally do an intersection test
if (edge.plane.findIntersections(planetModel, compareEdge.plane, oneBoundary.plane, otherBoundary.plane, oneCompareBoundary.plane, otherCompareBoundary.plane).length > 0) {
throw new IllegalArgumentException("polygon has intersecting edges");
}
}
}
}
}
*/
// Starting state:
// The stopping point
Edge stoppingPoint = edgeBuffer.pickOne();
@ -997,7 +1060,13 @@ public class GeoPolygonFactory {
System.out.println(" "+p);
}
*/
// We need to detect backtracks, and also situations where someone has tried to stitch together multiple segments into one long arc (> 180 degrees).
// To do this, every time we extend by a coplanar segment, we compute the total arc distance to the new endpoint, as
// well as a sum of the arc distances we've accumulated as we march forward. If these two numbers disagree, then
// we know there has been a backtrack or other anomaly.
// extend the edge, we compute the distance along the
final Edge startEdge = new Edge(pointList.get(startPlaneStartIndex), pointList.get(startPlaneEndIndex), startPlane, internalEdges.get(startPlaneStartIndex));
// Fill in the EdgeBuffer by walking around creating more stuff
Edge currentEdge = startEdge;
@ -1027,15 +1096,21 @@ public class GeoPolygonFactory {
if (currentEdge.plane.evaluateIsZero(newPoint)) {
// The new point is colinear with the current edge. We'll have to look for the first point that isn't.
int checkPointIndex = -1;
// Compute the arc distance before we try to extend
double accumulatedDistance = 0.0;
final Plane checkPlane = new Plane(pointList.get(startIndex), newPoint);
for (int i = 0; i < pointList.size(); i++) {
final int index = getLegalIndex(startIndex - 1 - i, pointList.size());
if (!checkPlane.evaluateIsZero(pointList.get(index))) {
checkPointIndex = index;
break;
} else {
accumulatedDistance += pointList.get(getLegalIndex(index+1, pointList.size())).arcDistance(pointList.get(index));
final double actualDistance = pointList.get(getLegalIndex(startIndex-1, pointList.size())).arcDistance(pointList.get(index));
if (Math.abs(actualDistance - accumulatedDistance) >= Vector.MINIMUM_RESOLUTION) {
throw new IllegalArgumentException("polygon backtracks over itself");
}
}
}
if (checkPointIndex == -1) {
throw new IllegalArgumentException("polygon is illegal (linear)");
}
pointToPresent = pointList.get(checkPointIndex);

40
lucene/spatial3d/src/test/org/apache/lucene/spatial3d/geom/GeoPolygonTest.java
View File

@ -378,4 +378,44 @@ shape:
final GeoPolygon p = GeoPolygonFactory.makeGeoPolygon(PlanetModel.WGS84, points, null);
}
@Test
public void testPolygonIntersectionFailure1() {
final PlanetModel pm = PlanetModel.WGS84;
//[junit4] > Throwable #1: java.lang.AssertionError: invalid hits for shape=GeoCompositeMembershipShape:
//{[GeoConvexPolygon: {planetmodel=PlanetModel.WGS84, points=
//[[lat=0.2669499069140678, lon=-0.31249902828113546([X=0.9186752334433793, Y=-0.2968103450748192, Z=0.2640238502385029])],
//[lat=1.538559019421765, lon=0.0([X=0.03215971057004023, Y=0.0, Z=0.9972473454662941])],
//[lat=-0.5516194571595735, lon=0.0([X=0.8518418310766115, Y=0.0, Z=-0.5241686363384119])]], internalEdges={2}},
//GeoConvexPolygon: {planetmodel=PlanetModel.WGS84, points=
//[[lat=0.0, lon=-3.141592653589793([X=-1.0011188539924791, Y=-1.226017000107956E-16, Z=0.0])],
//[lat=-1.5707963267948966, lon=-2.2780601241431375([X=-3.9697069088211677E-17, Y=-4.644115432258393E-17, Z=-0.997762292022105])],
//[lat=0.2669499069140678, lon=-0.31249902828113546([X=0.9186752334433793, Y=-0.2968103450748192, Z=0.2640238502385029])]], internalEdges={2}},
//GeoConvexPolygon: {planetmodel=PlanetModel.WGS84, points=
//[[lat=0.2669499069140678, lon=-0.31249902828113546([X=0.9186752334433793, Y=-0.2968103450748192, Z=0.2640238502385029])],
//[lat=-0.5516194571595735, lon=0.0([X=0.8518418310766115, Y=0.0, Z=-0.5241686363384119])],
//[lat=0.0, lon=-3.141592653589793([X=-1.0011188539924791, Y=-1.226017000107956E-16, Z=0.0])]], internalEdges={0, 2}}]}
// Build the polygon
//[[lat=-0.5516194571595735, lon=0.0([X=0.8518418310766115, Y=0.0, Z=-0.5241686363384119])],
//[lat=0.0, lon=-3.141592653589793([X=-1.0011188539924791, Y=-1.226017000107956E-16, Z=0.0])],
//[lat=-1.5707963267948966, lon=-2.2780601241431375([X=-3.9697069088211677E-17, Y=-4.644115432258393E-17, Z=-0.997762292022105])],
//[lat=0.2669499069140678, lon=-0.31249902828113546([X=0.9186752334433793, Y=-0.2968103450748192, Z=0.2640238502385029])],
//[lat=1.538559019421765, lon=0.0([X=0.03215971057004023, Y=0.0, Z=0.9972473454662941])]]
List<GeoPoint> polyPoints = new ArrayList<>();
polyPoints.add(new GeoPoint(pm, -0.5516194571595735, 0.0));
polyPoints.add(new GeoPoint(pm, 0.0, -3.141592653589793));
polyPoints.add(new GeoPoint(pm, -1.5707963267948966, -2.2780601241431375));
polyPoints.add(new GeoPoint(pm, 0.2669499069140678, -0.31249902828113546));
polyPoints.add(new GeoPoint(pm, 1.538559019421765, 0.0));
// Make sure we catch the backtrack
boolean backtracks = false;
try {
GeoPolygonFactory.makeGeoPolygon(pm, polyPoints, 4, null);
} catch (IllegalArgumentException e) {
backtracks = true;
}
assertTrue(backtracks);
}
}