Posted by runiter on Sep 06, 2017; 2:28pm
URL: https://forum.jogamp.org/Exception-Comparison-method-violates-its-general-contract-tp4038173.html

During picking I get the following exception in some of my 3D models:

java.lang.IllegalArgumentException: Comparison method violates its general contract!
        at java.util.TimSort.mergeHi(TimSort.java:899)
        at java.util.TimSort.mergeAt(TimSort.java:516)
        at java.util.TimSort.mergeForceCollapse(TimSort.java:457)
        at java.util.TimSort.sort(TimSort.java:254)
        at java.util.Arrays.sort(Arrays.java:1512)
        at java.util.ArrayList.sort(ArrayList.java:1454)
        at java.util.Collections.sort(Collections.java:175)
        at com.ardor3d.intersection.PickResults.getPickData(PickResults.java:73)

I tracked it to the following file:

https://github.com/gouessej/Ardor3D/blob/master/ardor3d-core/src/main/java/com/ardor3d/intersection/PickResults.java

In particular the following code:

    private static class DistanceComparator implements Comparator<PickData> {
        @Override
        public int compare(final PickData o1, final PickData o2) {
            if (o1.getIntersectionRecord().getClosestDistance() <= o2.getIntersectionRecord().getClosestDistance()) {
                return -1;
            }
            return 1;
        }
    }

Shouldn't the above code return zero when o1 and o2 distances are equal?