Fix bug in intersection of non-contiguous SpanSets

lsst · Dec 4, 2024 · 1413f48 · 1413f48
1 parent af9ad5d
commit 1413f48
Showing 1 changed file with 5 additions and 3 deletions.
diff --git a/src/geom/SpanSet.cc b/src/geom/SpanSet.cc
@@ -727,16 +727,18 @@ std::shared_ptr<SpanSet> SpanSet::intersect(SpanSet const& other) const {
         return std::make_shared<SpanSet>(this->_spanVector);
     }
     std::vector<Span> tempVec;
-    auto otherIter = other.begin();
+    auto otherBeginIter = other.begin();
     for (auto const& spn : _spanVector) {
-        while (otherIter != other.end() && otherIter->getY() <= spn.getY()) {
+        while(otherBeginIter != other.end() && otherBeginIter->getY() < spn.getY()) {
+            ++otherBeginIter;
+        }
+        for (auto otherIter = otherBeginIter; otherIter != other.end() && otherIter->getY() <= spn.getY(); ++otherIter) {
             if (spansOverlap(spn, *otherIter)) {
                 auto newMin = std::max(spn.getMinX(), otherIter->getMinX());
                 auto newMax = std::min(spn.getMaxX(), otherIter->getMaxX());
                 auto newSpan = Span(spn.getY(), newMin, newMax);
                 tempVec.push_back(newSpan);
             }
-            ++otherIter;
         }
     }
     return std::make_shared<SpanSet>(std::move(tempVec));