Add comment for fix, entry to CHANGES.md and fix formatting.

CHANGES.md

@@ -33,6 +33,7 @@
 - The `EntityCollection#add` method was documented to throw a `DeveloperError` for duplicate IDs, but did throw a `RuntimeError` in this case. This is now changed to throw a `DeveloperError`. [#11776](https://github.com/CesiumGS/cesium/pull/11776)
 - Parts of the documentation have been updated to resolve potential issues with the generated TypedScript definitions. [#11776](https://github.com/CesiumGS/cesium/pull/11776)
 - Fixed type definition for `Camera.constrainedAxis`. [#11475](https://github.com/CesiumGS/cesium/issues/11475)
+- Fixed a geometry displacement on iOS devices that was caused by NaN value in `czm_translateRelativeToEye` function. [#7100](https://github.com/CesiumGS/cesium/issues/7100)
 
 #### @cesium/widgets
 

packages/engine/Source/Shaders/Builtin/Functions/translateRelativeToEye.glsl

@@ -34,7 +34,11 @@
 vec4 czm_translateRelativeToEye(vec3 high, vec3 low)
 {
     vec3 highDifference = high - czm_encodedCameraPositionMCHigh;
-    if (length(highDifference) == 0.0) highDifference = vec3(0);
+    // This check handles the case when NaN values have gotten into `highDifference`.
+    // Such a thing could happen on devices running iOS.
+    if (length(highDifference) == 0.0) {  
+        highDifference = vec3(0);  
+    }
     vec3 lowDifference = low - czm_encodedCameraPositionMCLow;
 
     return vec4(highDifference + lowDifference, 1.0);