Fix view extent

CHANGES.md

@@ -13,6 +13,7 @@ Beta Releases
 * Improved the quality of imagery near the poles when the imagery source uses a `GeographicTilingScheme`.
 * `CesiumTerrainProvider` now supports mesh-based terrain like the tiles created by STK Terrain Server.
 * Added `Intersections2D` class containing operations on 2D triangles.
+* Fixed viewing an extent. [#1431](https://github.com/AnalyticalGraphicsInc/cesium/issues/1431)
 * Use `performance.now()` instead of `Date.now()`, when available, to limit time spent loading terrain and imagery tiles.  This results in more consistent frame rates while loading tiles on some systems.
 * Added the ability for imagery providers to specify view-dependent attribution to be display in the `CreditDisplay`.  
 * View-dependent imagery source attribution is now added to the `CreditDisplay` by the `BingMapsImageryProvider`. 

Source/Scene/CameraController.js

@@ -979,28 +979,24 @@ define([
         Cartesian3.multiplyByScalar(center, 0.5, center);
         Cartesian3.add(southWest, center, center);
 
+        var mag = Cartesian3.magnitude(center);
+        if (mag < CesiumMath.EPSILON6) {
+            cart.longitude = (east + west) * 0.5;
+            cart.latitude = (north + south) * 0.5;
+            ellipsoid.cartographicToCartesian(cart, center);
+        }
+
         Cartesian3.subtract(northWest, center, northWest);
         Cartesian3.subtract(southEast, center, southEast);
         Cartesian3.subtract(northEast, center, northEast);
         Cartesian3.subtract(southWest, center, southWest);
 
-        cart.longitude = east;
-        cart.latitude = (north + south) * 0.5;
-        var midEast = ellipsoid.cartographicToCartesian(cart, cameraRF.direction);
-        cart.longitude = west;
-        var right = ellipsoid.cartographicToCartesian(cart, cameraRF.right);
-        Cartesian3.subtract(midEast, right, right);
+        var direction = ellipsoid.geodeticSurfaceNormal(center, cameraRF.direction);
+        Cartesian3.negate(direction, direction);
+        Cartesian3.normalize(direction, direction);
+        var right = Cartesian3.cross(direction, Cartesian3.UNIT_Z, cameraRF.right);
         Cartesian3.normalize(right, right);
-
-        cart.longitude = (east + west) * 0.5;
-        cart.latitude = north;
-        var midNorth = ellipsoid.cartographicToCartesian(cart, cameraRF.direction);
-        cart.latitude = south;
-        var up = ellipsoid.cartographicToCartesian(cart, cameraRF.up);
-        Cartesian3.subtract(midNorth, up, up);
-        Cartesian3.normalize(up, up);
-
-        var direction = Cartesian3.cross(up, right, cameraRF.direction);
+        var up = Cartesian3.cross(right, direction, cameraRF.up);
 
         var height = Math.max(
           Math.abs(Cartesian3.dot(up, northWest)),
@@ -1019,22 +1015,8 @@ define([
         var tanTheta = camera.frustum.aspectRatio * tanPhi;
         var d = Math.max(width / tanTheta, height / tanPhi);
 
-        if (!defined(result)) {
-            result = new Cartesian3();
-        }
-
-        var mag = Cartesian3.magnitude(center);
         var scalar = mag + d;
-
-        if (mag < CesiumMath.EPSILON6) {
-            cart.longitude = (east + west) * 0.5;
-            cart.latitude = (north + south) * 0.5;
-            ellipsoid.cartographicToCartesian(cart, center);
-            Cartesian3.normalize(center, center);
-        } else {
-            Cartesian3.normalize(center, center);
-        }
-
+        Cartesian3.normalize(center, center);
         return Cartesian3.multiplyByScalar(center, scalar, result);
     }
 

Specs/Scene/CameraControllerSpec.js

@@ -541,7 +541,7 @@ defineSuite([
         }).toThrowDeveloperError();
     });
 
-    it('views extent in 3D', function() {
+    it('views extent in 3D (1)', function() {
         var extent = new Extent(
                 -Math.PI,
                 -CesiumMath.PI_OVER_TWO,
@@ -554,6 +554,32 @@ defineSuite([
         expect(camera.right).toEqualEpsilon(Cartesian3.UNIT_Y, CesiumMath.EPSILON10);
     });
 
+    it('views extent in 3D (2)', function() {
+        var extent = new Extent(
+                CesiumMath.toRadians(21.25),
+                CesiumMath.toRadians(41.23),
+                CesiumMath.toRadians(21.51),
+                CesiumMath.toRadians(41.38));
+        controller.viewExtent(extent, Ellipsoid.WGS84);
+        expect(camera.position).toEqualEpsilon(new Cartesian3(4478207.335705587, 1753173.8165311918, 4197410.895448539), CesiumMath.EPSILON6);
+        expect(camera.direction).toEqualEpsilon(new Cartesian3(-0.6995107725362416, -0.2738515389883838, -0.6600681886740524), CesiumMath.EPSILON10);
+        expect(camera.up).toEqualEpsilon(new Cartesian3(-0.6146449843355883, -0.24062742347984528, 0.7512056884106748), CesiumMath.EPSILON10);
+        expect(camera.right).toEqualEpsilon(new Cartesian3(-0.36454934142973716, 0.9311840729217532, 0.0), CesiumMath.EPSILON10);
+    });
+
+    it('views extent in 3D (3)', function() {
+        var extent = new Extent(
+                CesiumMath.toRadians(90.0),
+                CesiumMath.toRadians(-50.0),
+                CesiumMath.toRadians(157.0),
+                CesiumMath.toRadians(0.0));
+        controller.viewExtent(extent);
+        expect(camera.position).toEqualEpsilon(new Cartesian3(-6141929.663019788, 6904446.963087202, -5087100.779249599), CesiumMath.EPSILON6);
+        expect(camera.direction).toEqualEpsilon(new Cartesian3(0.5813363216621468, -0.6535089167170689, 0.48474135050314004), CesiumMath.EPSILON10);
+        expect(camera.up).toEqualEpsilon(new Cartesian3(-0.3221806693208934, 0.3621792280122498, 0.8746575461930182), CesiumMath.EPSILON10);
+        expect(camera.right).toEqualEpsilon(new Cartesian3(-0.7471597536218517, -0.6646444933705039, 0.0), CesiumMath.EPSILON10);
+    });
+
     it('views extent in 3D across IDL', function() {
         var extent = new Extent(
                 0.1,