From 76cd52325d17f76c8ebb6ecb6da3a49f1faa9ba6 Mon Sep 17 00:00:00 2001
From: Frederic Junod <frederic.junod@camptocamp.com>
Date: Wed, 7 Feb 2018 14:22:07 +0100
Subject: [PATCH 1/2] Fix getIntersection return value when an opt extent is
 provided

The return value was not an empty extent when the extents didn't intersect.
---
 test/spec/ol/extent.test.js | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/test/spec/ol/extent.test.js b/test/spec/ol/extent.test.js
index 1d83f0d656..e0984eb4b9 100644
--- a/test/spec/ol/extent.test.js
+++ b/test/spec/ol/extent.test.js
@@ -291,6 +291,20 @@ describe('ol.extent', function() {
       expect(_ol_extent_.getIntersection(north, west)).to.eql([-180, 0, 0, 90]);
       expect(_ol_extent_.getIntersection(east, south)).to.eql([0, -90, 180, 0]);
     });
+
+
+    it('can take an destination extent', function() {
+      const world = [-180, -90, 180, 90];
+      const north = [-180, 0, 180, 90];
+      const none = _ol_extent_.createEmpty();
+      let tmpExtent = [-180, 45, 180, 90];
+      expect(_ol_extent_.getIntersection(world, north, tmpExtent)).to.eql(north);
+      expect(_ol_extent_.getIntersection(world, none, tmpExtent)).to.eql(none);
+
+      tmpExtent = [-180, -90, 180, 90];
+      expect(_ol_extent_.getIntersection(tmpExtent, north, tmpExtent)).to.eql(north);
+    });
+
   });
 
   describe('containsCoordinate', function() {

From b2d3d142f03cb854dad24b3b9dcce2eddc94cb71 Mon Sep 17 00:00:00 2001
From: Frederic Junod <frederic.junod@camptocamp.com>
Date: Wed, 7 Feb 2018 14:52:54 +0100
Subject: [PATCH 2/2] Pass destination extent to avoid garbage generation

---
 src/ol/VectorImageTile.js | 2 +-
 src/ol/extent.js          | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/ol/VectorImageTile.js b/src/ol/VectorImageTile.js
index bde4b57c76..6a57370d1e 100644
--- a/src/ol/VectorImageTile.js
+++ b/src/ol/VectorImageTile.js
@@ -97,7 +97,7 @@ const VectorImageTile = function(tileCoord, state, sourceRevision, format,
         sourceTileGrid.getTileCoordExtent(sourceTileCoord));
       const sourceExtent = sourceTileGrid.getExtent();
       if (sourceExtent) {
-        sharedExtent = getIntersection(sharedExtent, sourceExtent);
+        sharedExtent = getIntersection(sharedExtent, sourceExtent, sharedExtent);
       }
       if (getWidth(sharedExtent) / resolution >= 0.5 &&
           getHeight(sharedExtent) / resolution >= 0.5) {
diff --git a/src/ol/extent.js b/src/ol/extent.js
index b90eaf9006..53567b6765 100644
--- a/src/ol/extent.js
+++ b/src/ol/extent.js
@@ -593,6 +593,8 @@ export function getIntersection(extent1, extent2, opt_extent) {
     } else {
       intersection[3] = extent2[3];
     }
+  } else {
+    createOrUpdateEmpty(intersection);
   }
   return intersection;
 }