Revert change to make distance to bounding sphere signed.

CHANGES.md

@@ -3,9 +3,6 @@ Change Log
 
 ### 1.45 - 2018-05-01
 
-##### Breaking Changes :mega:
-* `Camera.distanceToBoundingSphere` now returns the signed distance to the bounding sphere. Positive values indicate that the bounding sphere is in the positive half-plane of the camera position and view direction while a negative value indicates it is in the negative half-plane.
-
 ##### Additions :tada:
 * Added option `logDepthBuffer` to `Viewer`. With this option there is typically a single frustum using logarithmic depth rendered. This increases performance by issuing less draw calls to the GPU and helps to avoid artifacts on the connection of two frustums. [#5851](https://github.com/AnalyticalGraphicsInc/cesium/pull/5851)
 * When a log depth buffer is supported, the frustum near and far planes default to `0.1` and `1e10` respectively.
@@ -20,6 +17,7 @@ Change Log
 * Fix Firefox WebGL console warnings. [#5912](https://github.com/AnalyticalGraphicsInc/cesium/issues/5912)
 * Fix parsing Cesium.js in older browsers that do not support all TypedArray types. [#6396](https://github.com/AnalyticalGraphicsInc/cesium/pull/6396)
 * Fix flicker when adding, removing, or modifiying entities. [#3945](https://github.com/AnalyticalGraphicsInc/cesium/issues/3945)
+
 ##### Additions :tada:
 * Improved `MapboxImageryProvider` performance by 300% via `tiles.mapbox.com` subdomain switching. [#6426](https://github.com/AnalyticalGraphicsInc/cesium/issues/6426)
 

Source/Scene/Camera.js

@@ -2574,13 +2574,10 @@ define([
     var scratchProj = new Cartesian3();
 
     /**
-     * Return the signed distance from the camera to the front of the bounding sphere.
-     * <p>
-     * Positive values indicate that the bounding sphere is in the positive half-plane of the camera position and view direction while a negative value indicates it is in the negative half-plane.
-     * </p>
+     * Return the distance from the camera to the front of the bounding sphere.
      *
      * @param {BoundingSphere} boundingSphere The bounding sphere in world coordinates.
-     * @returns {Number} The signed distance to the bounding sphere.
+     * @returns {Number} The distance to the bounding sphere.
      */
     Camera.prototype.distanceToBoundingSphere = function(boundingSphere) {
         //>>includeStart('debug', pragmas.debug);
@@ -2590,10 +2587,8 @@ define([
         //>>includeEnd('debug');
 
         var toCenter = Cartesian3.subtract(this.positionWC, boundingSphere.center, scratchToCenter);
-        var distance = -Cartesian3.dot(toCenter, this.directionWC);
-        var proj = Cartesian3.multiplyByScalar(this.directionWC, distance, scratchProj);
-        var unsignedDistance = Math.abs(Cartesian3.magnitude(proj) - boundingSphere.radius);
-        return distance < 0.0 ? -unsignedDistance : unsignedDistance;
+        var proj = Cartesian3.multiplyByScalar(this.directionWC, Cartesian3.dot(toCenter, this.directionWC), scratchProj);
+        return Math.max(0.0, Cartesian3.magnitude(proj) - boundingSphere.radius);
     };
 
     var scratchPixelSize = new Cartesian2();
@@ -2620,9 +2615,6 @@ define([
         //>>includeEnd('debug');
 
         var distance = this.distanceToBoundingSphere(boundingSphere);
-        if (distance < 0.0) {
-            return 0.0;
-        }
         var pixelSize = this.frustum.getPixelDimensions(drawingBufferWidth, drawingBufferHeight, distance, scratchPixelSize);
         return Math.max(pixelSize.x, pixelSize.y);
     };