Hi Gerd
Here is patch that prevents possible underflow when node is very close
to an almost horizontal or vertical line and incorrect results when
exactly on this line.
Ticker
Index: src/uk/me/parabola/util/IsInUtil.java
===================================================================
--- src/uk/me/parabola/util/IsInUtil.java (revision 4495)
+++ src/uk/me/parabola/util/IsInUtil.java (working copy)
@@ -351,29 +351,29 @@
++lhsCount; // definite line segment all slightly to the left
} else { // need to consider this segment more carefully.
if (leadLat == trailLat)
- lonDif = 0; // dif meaningless; will be ignored in crossing calc, 0 handled for distToLine calc
+ lonDif = Double.NaN;
else
lonDif = nodeLon - trailLon - (double)(nodeLat - trailLat) / (leadLat - trailLat) * (leadLon - trailLon);
if (leadLon == trailLon)
- latDif = 0; // ditto
+ latDif = Double.NaN;
else
latDif = nodeLat - trailLat - (double)(nodeLon - trailLon) / (leadLon - trailLon) * (leadLat - trailLat);
// calculate distance to segment using right-angle attitude theorem
- final double lonDifSqrd = lonDif*lonDif;
- final double latDifSqrd = latDif*latDif;
log.debug("inBox", leadLon-nodeLon, leadLat-nodeLat, trailLon-nodeLon, trailLat-nodeLat, lonDif, latDif, lhsCount, rhsCount);
- // there a small area between the square EPS_HP*2 and the circle within, where, if polygon vertix and
+ // there is a small area between the square EPS_HP*2 and the circle within, where, if polygon vertix and
// segments are the other side, it might still be calculated as ON.
- if (lonDif == 0)
- distSqrd = latDifSqrd;
- else if (latDif == 0)
- distSqrd = lonDifSqrd;
+ if (Double.isNaN(lonDif))
+ distSqrd = latDif*latDif;
+ else if (Double.isNaN(latDif))
+ distSqrd = lonDif*lonDif;
+ else if (Math.abs(lonDif) < EPS_HP || Math.abs(latDif) < EPS_HP)
+ return ON;
else
- distSqrd = lonDifSqrd * latDifSqrd / (lonDifSqrd + latDifSqrd);
+ distSqrd = lonDif*lonDif * latDif*latDif / (lonDif*lonDif + latDif*latDif);
if (distSqrd < EPS_HP_SQRD)
return ON;
if ((trailLat <= nodeLat && leadLat > nodeLat) || // an upward crossing
- (trailLat > nodeLat && leadLat <= nodeLat)) { // a downward crossing
+ (trailLat > nodeLat && leadLat <= nodeLat)) { // a downward crossing
if (lonDif < 0)
++rhsCount; // a valid crossing right of nodeLon
else
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