Maintain camera heading, pitch, and roll on zoom

CHANGES.md

@@ -1,5 +1,9 @@
 Change Log
 ==========
+### 1.38 - 2017-10-02
+
+* Zoom about mouse now maintains camera heading, pitch, and roll [#4639](https://github.com/AnalyticalGraphicsInc/cesium/pull/5603)
+
 ### 1.37 - 2017-09-01
 
 * Breaking changes

CONTRIBUTORS.md

@@ -86,6 +86,8 @@ See [CONTRIBUTING.md](CONTRIBUTING.md) for details on how to contribute to Cesiu
    * [Jason Crow](https://github.com/jason-crow)
 * [Flightradar24 AB](https://www.flightradar24.com)
    * [Aleksei Kalmykov](https://github.com/kalmykov)
+* [BIT Systems](http://www.caci.com/bit-systems)
+   * [William Wall](https://github.com/wallw-bits)
 * [virtualcitySYSTEMS GmbH](https://www.virtualcitysystems.de)
    * [Jannes Bolling](https://github.com/jbo023)
 

Source/Scene/ScreenSpaceCameraController.js

@@ -8,6 +8,7 @@ define([
         '../Core/destroyObject',
         '../Core/DeveloperError',
         '../Core/Ellipsoid',
+        '../Core/HeadingPitchRoll',
         '../Core/IntersectionTests',
         '../Core/isArray',
         '../Core/KeyboardEventModifier',
@@ -35,6 +36,7 @@ define([
         destroyObject,
         DeveloperError,
         Ellipsoid,
+        HeadingPitchRoll,
         IntersectionTests,
         isArray,
         KeyboardEventModifier,
@@ -446,6 +448,9 @@ define([
     var scratchCartesian = new Cartesian3();
     var scratchCartesianTwo = new Cartesian3();
     var scratchCartesianThree = new Cartesian3();
+    var scratchZoomViewOptions = {
+      orientation: new HeadingPitchRoll()
+    };
 
     function handleZoom(object, startPosition, movement, zoomFactor, distanceMeasure, unitPositionDotDirection) {
         var percentage = 1.0;
@@ -485,6 +490,11 @@ define([
         var camera = scene.camera;
         var mode = scene.mode;
 
+        var orientation = scratchZoomViewOptions.orientation;
+        orientation.heading = camera.heading;
+        orientation.pitch = camera.pitch;
+        orientation.roll = camera.roll;
+
         if (camera.frustum instanceof OrthographicFrustum) {
             if (Math.abs(distance) > 0.0) {
                 camera.zoomIn(distance);
@@ -646,6 +656,7 @@ define([
                         Cartesian3.cross(camera.direction, camera.up, camera.right);
                         Cartesian3.cross(camera.right, camera.direction, camera.up);
 
+                        camera.setView(scratchZoomViewOptions);
                         return;
                     }
 
@@ -691,6 +702,8 @@ define([
         } else {
             camera.zoomIn(distance);
         }
+
+        camera.setView(scratchZoomViewOptions);
     }
 
     var translate2DStart = new Ray();

Specs/Scene/ScreenSpaceCameraControllerSpec.js

@@ -849,19 +849,31 @@ defineSuite([
     it('zoom in 3D with wheel', function() {
         setUp3D();
         var position = Cartesian3.clone(camera.position);
+        var heading = camera.heading;
+        var pitch = camera.pitch;
+        var roll = camera.roll;
 
         simulateMouseWheel(120);
         updateController();
         expect(Cartesian3.magnitude(position)).toBeGreaterThan(Cartesian3.magnitude(camera.position));
+        expect(camera.heading).toBeCloseTo(heading, 10);
+        expect(camera.pitch).toBeCloseTo(pitch, 10);
+        expect(camera.roll).toBeCloseTo(roll, 10);
     });
 
     it('zoom out in 3D with wheel', function() {
         setUp3D();
         var position = Cartesian3.clone(camera.position);
+        var heading = camera.heading;
+        var pitch = camera.pitch;
+        var roll = camera.roll;
 
         simulateMouseWheel(-120);
         updateController();
         expect(Cartesian3.magnitude(position)).toBeLessThan(Cartesian3.magnitude(camera.position));
+        expect(camera.heading).toBeCloseTo(heading, 10);
+        expect(camera.pitch).toBeCloseTo(pitch, 10);
+        expect(camera.roll).toBeCloseTo(roll, 10);
     });
 
     it('zoom in 3D with orthographic projection', function() {