Merge pull request #8576 from AnalyticalGraphicsInc/planeGeometryFix

Fixed crash when creating plane with translation and normal on the Z axis

Author: Hannah

CHANGES.md

@@ -47,6 +47,7 @@ Change Log
 * Fixed a crash that could occur when an entity was deleted while the corresponding `Primitive` was being created asynchronously. [#8569](https://github.com/AnalyticalGraphicsInc/cesium/pull/8569)
 * Fixed a crash when calling `camera.lookAt` with the origin as the target. This could happen when looking at a tileset with the origin as its center. [#8571](https://github.com/AnalyticalGraphicsInc/cesium/pull/8571)
 * Fixed a bug where `camera.viewBoundingSphere` was modifying the `offset` parameter [#8438](https://github.com/AnalyticalGraphicsInc/cesium/pull/8438)
+* Fixed a crash when creating a plane with both position and normal on the Z-axis. [#8576](https://github.com/AnalyticalGraphicsInc/cesium/pull/8576)
 
 ### 1.65.0 - 2020-01-06
 

Source/DataSources/PlaneGeometryUpdater.js

@@ -240,6 +240,9 @@ import Property from './Property.js';
         var up = ellipsoid.geodeticSurfaceNormal(translation, scratchAxis2);
         if (CesiumMath.equalsEpsilon(Math.abs(Cartesian3.dot(up, transformedNormal)), 1.0, CesiumMath.EPSILON8)) {
             up = Cartesian3.clone(Cartesian3.UNIT_Z, up);
+            if (CesiumMath.equalsEpsilon(Math.abs(Cartesian3.dot(up, transformedNormal)), 1.0, CesiumMath.EPSILON8)) {
+                up = Cartesian3.clone(Cartesian3.UNIT_X, up);
+            }
         }
 
         var left = Cartesian3.cross(up, transformedNormal, scratchAxis);