Merge pull request #9970 from CesiumGS/camera-changed-fix

updating Camera.changed to account for changes in heading

CHANGES.md

@@ -18,6 +18,7 @@
 - Fixed handling of vec3 vertex colors in `ModelExperimental`. [#9955](https://github.com/CesiumGS/cesium/pull/9955)
 - Fixed handling of Draco quantized vec3 vertex colors in `ModelExperimental`. [#9957](https://github.com/CesiumGS/cesium/pull/9957)
 - Fixed handling of vec3 vertex colors in `CustomShaderPipelineStage`. [#9964](https://github.com/CesiumGS/cesium/pull/9964)
+- Fixes how `Camera.changed` handles changes in `heading`. [#9970](https://github.com/CesiumGS/cesium/pull/9970)
 - Fixed handling of subtree root transforms in `Implicit3DTileContent`. [#9971](https://github.com/CesiumGS/cesium/pull/9971)
 - Fixed issue in `ModelExperimental` where indices were not the correct data type after draco decode. [#9974](https://github.com/CesiumGS/cesium/pull/9974)
 - Fixed WMS 1.3.0 `GetMap` `bbox` parameter so that it follows the axis ordering as defined in the EPSG database. [#9797](https://github.com/CesiumGS/cesium/pull/9797)

Source/Scene/Camera.js

@@ -198,6 +198,7 @@ function Camera(scene) {
   this._changedPosition = undefined;
   this._changedDirection = undefined;
   this._changedFrustum = undefined;
+  this._changedHeading = undefined;
 
   /**
    * The amount the camera has to change before the <code>changed</code> event is raised. The value is a percentage in the [0, 1] range.
@@ -361,6 +362,25 @@ Camera.prototype._updateCameraChanged = function () {
 
   var percentageChanged = camera.percentageChanged;
 
+  var currentHeading = camera.heading;
+
+  if (!defined(camera._changedHeading)) {
+    camera._changedHeading = currentHeading;
+  }
+
+  var delta =
+    Math.abs(camera._changedHeading - currentHeading) % CesiumMath.TWO_PI;
+  delta = delta > CesiumMath.PI ? CesiumMath.TWO_PI - delta : delta;
+
+  // Since delta is computed as the shortest distance between two angles
+  // the percentage is relative to the half circle.
+  var headingChangedPercentage = delta / Math.PI;
+
+  if (headingChangedPercentage > percentageChanged) {
+    camera._changed.raiseEvent(headingChangedPercentage);
+    camera._changedHeading = currentHeading;
+  }
+
   if (camera._mode === SceneMode.SCENE2D) {
     if (!defined(camera._changedFrustum)) {
       camera._changedPosition = Cartesian3.clone(

Specs/Scene/SceneSpec.js

@@ -1309,6 +1309,30 @@ describe(
       s.destroyForSpecs();
     });
 
+    it("raises the camera changed event on heading changed", function () {
+      var s = createScene();
+
+      var spyListener = jasmine.createSpy("listener");
+      s.camera.changed.addEventListener(spyListener);
+
+      s.initializeFrame();
+      s.render();
+
+      s.camera.twistLeft(CesiumMath.PI * (s.camera.percentageChanged + 0.1));
+
+      s.initializeFrame();
+      s.render();
+
+      expect(spyListener.calls.count()).toBe(1);
+
+      var args = spyListener.calls.allArgs();
+      expect(args.length).toEqual(1);
+      expect(args[0].length).toEqual(1);
+      expect(args[0][0]).toBeGreaterThan(s.camera.percentageChanged);
+
+      s.destroyForSpecs();
+    });
+
     it("raises the camera changed event on position changed", function () {
       var s = createScene();
 
@@ -1318,7 +1342,7 @@ describe(
       s.initializeFrame();
       s.render();
 
-      s.camera.moveLeft(
+      s.camera.moveUp(
         s.camera.positionCartographic.height *
           (s.camera.percentageChanged + 0.1)
       );