Add configurable eye separation and focal length for VR

CHANGES.md

@@ -8,6 +8,7 @@ Change Log
 * Fixed a bug that caused KML ground overlays to appear distorted when rotation was applied. [#5914](https://github.com/AnalyticalGraphicsInc/cesium/issues/5914)
 * KML files load when a Network Link fails [#5871](https://github.com/AnalyticalGraphicsInc/cesium/pull/5871)
 * Adds `invertClassification` and `invertClassificationColor` to `Scene`. When `invertClassification` is `true`, any 3D Tiles geometry that is not classified by a `ClassificationPrimitive` or `GroundPrimitive` will have its color multiplied by `invertClassificationColor`. [#5836](https://github.com/AnalyticalGraphicsInc/cesium/pull/5836)
+* Added `eyeSeparation` and `focalLength` properties to `Scene` to configure VR settings. [#5917](https://github.com/AnalyticalGraphicsInc/cesium/pull/5917)
 * Added `customTags` property to the UrlTemplateImageryProvider to allow custom keywords in the template URL. [#5696](https://github.com/AnalyticalGraphicsInc/cesium/pull/5696)
 * Improved CZML Reference Properties example [#5754](https://github.com/AnalyticalGraphicsInc/cesium/pull/5754)
 

Source/Scene/Scene.js

@@ -653,6 +653,18 @@ define([
         this._actualInvertClassificationColor = Color.clone(this._invertClassificationColor);
         this._invertClassification = new InvertClassification();
 
+        /**
+         * The focal length for use when with cardboard or WebVR.
+         * @type {Number}
+         */
+        this.focalLength = undefined;
+
+        /**
+         * The eye separation distance in meters for use with cardboard or WebVR.
+         * @type {Number}
+         */
+        this.eyeSeparation = undefined;
+
         this._brdfLutGenerator = new BrdfLutGenerator();
 
         this._terrainExaggeration = defaultValue(options.terrainExaggeration, 1.0);
@@ -2282,8 +2294,8 @@ define([
             var savedCamera = Camera.clone(camera, scene._cameraVR);
 
             var near = camera.frustum.near;
-            var fo = near * 5.0;
-            var eyeSeparation = fo / 30.0;
+            var fo = near * defaultValue(scene.focalLength, 5.0);
+            var eyeSeparation = defaultValue(scene.eyeSeparation, fo / 30.0);
             var eyeTranslation = Cartesian3.multiplyByScalar(savedCamera.right, eyeSeparation * 0.5, scratchEyeTranslation);
 
             camera.frustum.aspectRatio = viewport.width / viewport.height;