In the example 3D Tiles dataset from Remoscape linked below, the instanced tree leaf polygons are double-sided without backface culling. But in Cesium for Unreal 2.26 in Unreal 5.7.4 they appear single-sided and backface-culled. I’m not sure if it worked better in previous versions, but it works fine in both CesiumJS and Cesium for Unity 1.23.2 (Unity 6000.4.9f1). So it should probably be considered a specific bug in Cesium for Unreal, right?
I’m just checking with the team about what the expected behaviour in Unreal is and if there’s any known limitations here. I’ll get back to you when I know more!
This is indeed a known limitation in Cesium for Unreal. We have a GitHub issue to track this here.
The best workaround would be to make a copy of the MI_CesiumThreeOverlaysAndClipping material and enable the Double-Sided property on that copy. Then, assign it to the Material slot on the Cesium3DTileset that requires that behavior.
We’d definitely like to make this functionality built-in so that you don’t have to do anything manually, but that’s the current state of things. :') Let us know if this helps for now!