Restore point order in polygons that don't require fixup

wagyu algorithm setup and checking if polygon fixup is required is expensive as much as fixing it - so we continue running wagyu for all geojson and, if attempt to restore original point order after wagyu.  Even with no polygon fixup, starting point in rings is changed.  This causes a disparity between GL-JS and GL-native, visible in implementation of fill-extrusion pattern.

Fixes: https://github.com/mapbox/mapbox-gl-native/issues/15268

2 files changed, 23 insertions, 8 deletions

diff --git a/platform/node/test/ignores.json b/platform/node/test/ignores.json
index 5814114a15..b23978cac4 100644
--- a/platform/node/test/ignores.json
+++ b/platform/node/test/ignores.json
@@ -47,13 +47,7 @@
   "render-tests/debug/tile": "https://github.com/mapbox/mapbox-gl-native/issues/3841",
   "render-tests/debug/tile-overscaled": "https://github.com/mapbox/mapbox-gl-native/issues/3841",
   "render-tests/extent/1024-circle": "needs investigation",
-  "render-tests/fill-extrusion-pattern/@2x": "https://github.com/mapbox/mapbox-gl-js/issues/3327",
-  "render-tests/fill-extrusion-pattern/function": "https://github.com/mapbox/mapbox-gl-js/issues/3327",
-  "render-tests/fill-extrusion-pattern/function-2": "https://github.com/mapbox/mapbox-gl-js/issues/3327",
-  "render-tests/fill-extrusion-pattern/literal": "https://github.com/mapbox/mapbox-gl-js/issues/3327",
-  "render-tests/fill-extrusion-pattern/opacity": "https://github.com/mapbox/mapbox-gl-js/issues/3327",
-  "render-tests/fill-extrusion-pattern/feature-expression": "https://github.com/mapbox/mapbox-gl-js/issues/3327",
-  "render-tests/fill-extrusion-pattern/tile-buffer": "https://github.com/mapbox/mapbox-gl-js/issues/3327",
+  "render-tests/fill-extrusion-pattern/tile-buffer": "https://github.com/mapbox/mapbox-gl-js/issues/4403",
   "render-tests/fill-pattern/literal": "FLAKY: do not re-enable without extensive testing - https://github.com/mapbox/mapbox-gl-native/issues/14423",
   "render-tests/fill-pattern/opacity": "FLAKY: do not re-enable without extensive testing - https://github.com/mapbox/mapbox-gl-native/issues/14870",
   "render-tests/fill-pattern/update-feature-state": "skip - port https://github.com/mapbox/mapbox-gl-js/pull/6263 - needs issue",
diff --git a/src/mbgl/tile/geometry_tile_data.cpp b/src/mbgl/tile/geometry_tile_data.cpp
index 5320df6893..7f4c3dbeb0 100644
--- a/src/mbgl/tile/geometry_tile_data.cpp
+++ b/src/mbgl/tile/geometry_tile_data.cpp
@@ -36,6 +36,27 @@ static GeometryCollection toGeometryCollection(MultiPolygon<int16_t>&& multipoly
     return result;
 }
 
+// Attempts to restore original point order in rings:
+// see https://github.com/mapbox/mapbox-gl-native/issues/15268.
+static GeometryCollection restorePointOrder(GeometryCollection&& rings, const GeometryCollection& originalRings) {
+    if (rings.size() != originalRings.size()) {
+        // No sense restoring starting point if polygons are changed.
+        return std::move(rings);
+    }
+
+    int i = 0;
+    for (auto& ring : rings) {
+        const auto originalRing = originalRings[i++];
+        auto item = find(ring.begin(), ring.end() - 1, originalRing[0]);
+        if (item != ring.end()) {
+            rotate(ring.begin(), item, ring.end() - 1);
+            // Close the ring.
+            ring.back() = ring.front();
+        }
+    }
+    return std::move(rings);
+}
+
 GeometryCollection fixupPolygons(const GeometryCollection& rings) {
     using namespace mapbox::geometry::wagyu;
 
@@ -48,7 +69,7 @@ GeometryCollection fixupPolygons(const GeometryCollection& rings) {
     MultiPolygon<int16_t> multipolygon;
     clipper.execute(clip_type_union, multipolygon, fill_type_even_odd, fill_type_even_odd);
 
-    return toGeometryCollection(std::move(multipolygon));
+    return restorePointOrder(toGeometryCollection(std::move(multipolygon)), rings);
 }
 
 std::vector<GeometryCollection> classifyRings(const GeometryCollection& rings) {