Fix curve walk edge case where the curve legitimately returns to the previous faceterrain-for-networks

2 files changed, 8 insertions, 4 deletions

diff --git a/game/geoData.cpp b/game/geoData.cpp
index 45e6590..f0e38d0 100644
--- a/game/geoData.cpp
+++ b/game/geoData.cpp
@@ -315,16 +315,14 @@ GeoData::walkUntil(const PointFace & from, GlobalPosition2D to, GlobalPosition2D
 	while (step.current.is_valid() && !op(step)) {
 		step.previous = step.current;
 		for (const auto next : fh_range(step.current)) {
-			if (opposite_halfedge_handle(next) == step.exitHalfedge) {
-				continue;
-			}
 			step.current = opposite_face_handle(next);
 			if (step.current.is_valid()) {
 				const auto e1 = point(to_vertex_handle(next));
 				const auto e2 = point(to_vertex_handle(opposite_halfedge_handle(next)));
 				if (const auto intersect = arc.crossesLineAt(e1, e2)) {
 					step.exitHalfedge = next;
-					step.exitPosition = intersect.value().first;
+					arc.ep0 = step.exitPosition = intersect.value().first;
+					arc.first = std::nextafter(intersect.value().second, INFINITY);
 					break;
 				}
 			}
diff --git a/test/test-geoData.cpp b/test/test-geoData.cpp
index 049d896..8e5ef2d 100644
--- a/test/test-geoData.cpp
+++ b/test/test-geoData.cpp
@@ -216,6 +216,11 @@ BOOST_DATA_TEST_CASE(walkTerrainCurveSetsFromFace,
 								{310050000, 490008845},
 								{310003003, 490003003},
 						}},
+				{{310999999, 490205000}, {310999999, 490203000}, {310999000, 490204000}, {1631, 1632, 1631},
+						{
+								{311000000, 490204999},
+								{311000000, 490203001},
+						}},
 		}),
 		from, to, centre, visits, exits)
 {
@@ -225,6 +230,7 @@ BOOST_DATA_TEST_CASE(walkTerrainCurveSetsFromFace,
 	std::vector<GlobalPosition2D> exited;
 	BOOST_CHECK_NO_THROW(fixedTerrtain.walk(from, to, centre, [&](const auto & step) {
 		visited.emplace_back(step.current.idx());
+		BOOST_REQUIRE(!std::ranges::contains(exited, step.exitPosition));
 		exited.emplace_back(step.exitPosition);
 	}));
 	BOOST_CHECK_EQUAL_COLLECTIONS(visited.begin(), visited.end(), visits.begin(), visits.end());