I’ve got a great looking billboard with a semi-transparent background from a PNG. I have it render above the earth enough to draw a few polylines and spheres, which look good underneath. The positioning of the billboard is fine. The problem happens as soon as I try to add new geometry (sphere or polyline collection) underneath the billboard. All new polyline collections and spheres are only displayed until they go under the billboard.
Because my billboards are only going to be shown for 10 seconds or less, I have temporarily solved this problem by keeping a pool of empty polyline collections that are added to the scene when first created. When I actually need to draw a polyline, I just use one of the existing collections instead of making a new one (which would end up being created after the billboard, and therefore problematic). Perhaps this is the best way to do it anyhow, but it seems like it may be a bug with the billboard opacity handling. For example, it would be harder to maintain a pool of unused polyline collections large enough to keep the billboard shown for half an hour. Any thoughts?