Don't clamp GeoJsonDataSource billboards to ground unless clampToGrou…

…nd is true.

CHANGES.md

@@ -11,7 +11,7 @@ Change Log
 * Fixed a bug affected models with multiple meshes without indices. [#4237](https://github.com/AnalyticalGraphicsInc/cesium/issues/4237)
 * Fixed a glTF transparency bug where `blendFuncSeparate` parameters were loaded in the wrong order. [#4435](https://github.com/AnalyticalGraphicsInc/cesium/pull/4435)
 * Fixed a bug where creating a custom geometry with attributes and indices that have values that are not a typed array would cause a crash. [#4419](https://github.com/AnalyticalGraphicsInc/cesium/pull/4419)
-* `KmlDataSource` was not honoring the `clampToGround` option for billboards and labels and was instead always clamping, reducing performance in cases when it was unneeded.
+* `KmlDataSource` and `GeoJsonDataSource` were not honoring the `clampToGround` option for billboards and labels and was instead always clamping, reducing performance in cases when it was unneeded.
 * Fixed a bug with rotated, textured rectangles. [#4430](https://github.com/AnalyticalGraphicsInc/cesium/pull/4430)
 * Fixed a bug when morphing from 2D to 3D. [#4388](https://github.com/AnalyticalGraphicsInc/cesium/pull/4388)
 * Fixed a bug where when KML features had duplicate IDs, only one was drawn. [#3941](https://github.com/AnalyticalGraphicsInc/cesium/issues/3941)

Source/DataSources/GeoJsonDataSource.js

@@ -285,7 +285,7 @@ define([
         billboard.verticalOrigin = new ConstantProperty(VerticalOrigin.BOTTOM);
 
         // Clamp to ground if there isn't a height specified
-        if (coordinates.length === 2) {
+        if (coordinates.length === 2 && options.clampToGround) {
             billboard.heightReference = HeightReference.CLAMP_TO_GROUND;
         }