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LUCENE-8032: Limit size of exact circle so that approximation planes don't intersect at angles greater than 180 degrees.

This commit is contained in:
Karl Wright 2017-11-02 10:43:40 -04:00
parent c6fb5ff80e
commit 154edb8e3c
1 changed files with 9 additions and 3 deletions
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12
lucene/spatial3d/src/java/org/apache/lucene/spatial3d/geom/GeoExactCircle.java
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@ -65,7 +65,10 @@ class GeoExactCircle extends GeoBaseCircle {
throw new IllegalArgumentException("Cutoff angle out of bounds");
if (cutoffAngle < Vector.MINIMUM_RESOLUTION)
throw new IllegalArgumentException("Cutoff angle cannot be effectively zero");
// We cannot allow exact circles to be large enough so that planes intersect at greater than 180 degrees. This guarantees it.
if (cutoffAngle > Math.PI * 0.5)
throw new IllegalArgumentException("Cutoff angle out of bounds");
this.center = new GeoPoint(planetModel, lat, lon);
this.cutoffAngle = cutoffAngle;
@ -87,15 +90,18 @@ class GeoExactCircle extends GeoBaseCircle {
final GeoPoint southPoint = planetModel.surfacePointOnBearing(center, cutoffAngle, Math.PI);
final GeoPoint eastPoint = planetModel.surfacePointOnBearing(center, cutoffAngle, Math.PI * 0.5);
final GeoPoint westPoint = planetModel.surfacePointOnBearing(center, cutoffAngle, Math.PI * 1.5);
final GeoPoint edgePoint;
if (planetModel.c > planetModel.ab) {
// z can be greater than x or y, so ellipse is longer in height than width
slices.add(new ApproximationSlice(center, eastPoint, Math.PI * 0.5, westPoint, Math.PI * -0.5, northPoint, 0.0));
slices.add(new ApproximationSlice(center, westPoint, Math.PI * 1.5, eastPoint, Math.PI * 0.5, southPoint, Math.PI));
edgePoint = eastPoint;
} else {
// z will be less than x or y, so ellipse is shorter than it is tall
slices.add(new ApproximationSlice(center, northPoint, Math.PI * 2.0, southPoint, Math.PI, eastPoint, Math.PI * 0.5));
slices.add(new ApproximationSlice(center, southPoint, Math.PI, northPoint, 0.0, westPoint, Math.PI * 1.5));
edgePoint = northPoint;
}
// Now, iterate over slices until we have converted all of them into safe SidedPlanes.
@ -131,7 +137,7 @@ class GeoExactCircle extends GeoBaseCircle {
//System.out.println("Number of planes needed: "+circlePlanes.size());
this.edgePoints = new GeoPoint[]{northPoint};
this.edgePoints = new GeoPoint[]{edgePoint};
this.circlePlanes = circlePlanes;
// Compute bounds
if (circlePlanes.size() == 1) {