Just checking in that for styling geojsondatasource layers you cannot set clampToGround, right? Or else the outline of polygons, for example, disappears.
It’s quite maddening and thought maybe a newer release would fix it but seems to have not done it.
Any tips?
Tyler, I have the same question, but I am SO HAPPY to have the limited clampToGround capability for polygons, after waiting SO LONG for that ability, I am not getting too upset about missing outlines. Getting used to open source software: we can’t have everything we want, unless someone in the developer community (ourselves?) is willing to volunteer time to make it happen. The current implementation of clampToGround will probably be around a long time. The current limitations on unsupported KML datasource element will probably be around a long time. The incomplete work on GPX and shapefile support has been languishing since May 2015… and probably will remain uncompleted for a long time. The Cesium team and AGI seem to have other priorities than completing the Cesium features necessary to migrate from a Google Earth plugin; forget about using Cesium as a GIS data viewer unless we’re willing to overlook the missing features, or willing to contribute. I share your pain - 3 years ago I started pitching Cesium as a 3D GIS viewer, and its taken so long for Cesium to clamp a polygon to 3D terrain that my original client has lost interest. Best regards to the Cesium team, I respect that you are working with limited resources, and look forward to any progress on these issues (clampToGround, KML, GPX & shapefiles…)
-Jon
Hello,
Unfortunately we do not currently have support for polylines on terrain, so we are not able to do outlines on polygons when they are clamped to ground. it’s something we would like to add soon, but it’s a difficult problem to solve and we still need to do research to figure out the best way to accomplish this so the lines render efficiently.
Best,
Hannah
Okay, thanks for the replies 
I guess the workaround will be to load image layers instead of vectors, but can’t imagine I’ll have good performance or quality hehe