Fix DeveloperError when zooming in 2D

CHANGES.md

@@ -9,6 +9,7 @@ Beta Releases
 * Breaking changes:
   * Renamed `Viewer.automaticallyTrackFirstDataSourceClock` to `Viewer.automaticallyTrackDataSourceClocks`.
 * Added new `SelectionIndicator` and `InfoBox` widgets to `Viewer`, activated by `viewerDynamicObjectMixin`.
+* Fix developer error when zooming in 2D. If the zoom would create an invalid frustum, nothing is done. [#1432](https://github.com/AnalyticalGraphicsInc/cesium/issues/1432)
 * `OpenStreetMapImageryProvider` now supports imagery with a minimum level.
 * 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.

Source/Scene/CameraController.js

@@ -639,6 +639,11 @@ define([
             newLeft = -maxRight;
         }
 
+        if (newRight <= newLeft) {
+            newRight = 1.0;
+            newLeft = -1.0;
+        }
+
         var ratio = frustum.top / frustum.right;
         frustum.right = newRight;
         frustum.left = newLeft;

Source/Scene/ScreenSpaceCameraController.js

@@ -446,9 +446,11 @@ define([
         var p1 = Cartesian3.subtract(end, position, scratchTranslateP1);
         var direction = Cartesian3.subtract(p0, p1, scratchTranslateP0);
         var distance = Cartesian3.magnitude(direction);
-        Cartesian3.normalize(direction, direction);
 
-        cameraController.move(direction, distance);
+        if (distance > 0.0) {
+            Cartesian3.normalize(direction, direction);
+            cameraController.move(direction, distance);
+        }
     }
 
     function zoom2D(controller, movement) {

Specs/Scene/CameraControllerSpec.js

@@ -416,7 +416,7 @@ defineSuite([
         expect(camera.frustum.bottom).toEqual(-0.75, CesiumMath.EPSILON10);
     });
 
-    it('clamps zoom in 2D', function() {
+    it('clamps zoom out in 2D', function() {
         var frustum = new OrthographicFrustum();
         frustum.near = 1.0;
         frustum.far = 2.0;
@@ -442,6 +442,29 @@ defineSuite([
         expect(frustum.bottom).toEqual(-frustum.top);
     });
 
+    it('clamps zoom in in 2D', function() {
+        var frustum = new OrthographicFrustum();
+        frustum.near = 1.0;
+        frustum.far = 2.0;
+        frustum.left = -2.0;
+        frustum.right = 2.0;
+        frustum.top = 1.0;
+        frustum.bottom = -1.0;
+        camera.frustum = frustum;
+
+        var ellipsoid = Ellipsoid.WGS84;
+        var projection = new GeographicProjection(ellipsoid);
+        controller.update(SceneMode.SCENE2D, { projection : projection });
+
+        var max = projection.project(new Cartographic(Math.PI, CesiumMath.toRadians(85.05112878)));
+        var factor = 1000.0;
+        var dx = max.x * factor;
+
+        controller.zoomIn(dx * 2.0);
+        expect(frustum.right).toEqual(1.0);
+        expect(frustum.left).toEqual(-1.0);
+    });
+
     it('zooms in 3D', function() {
         controller.zoomIn(zoomAmount);
         expect(camera.position).toEqualEpsilon(new Cartesian3(0.0, 0.0, 1.0 - zoomAmount), CesiumMath.EPSILON10);