loading property
Resources this view waits for before it reveals the scene.
While the group is loading (and while the engine's shared static resources are still initializing), the scene is held off-screen and loadingBuilder is shown in its place, so a half-built scene is never drawn. Once the group and static resources are ready, the fully assembled scene is revealed in one frame. Leave null to render as soon as static resources are ready (the historical behavior).
Implementation
final ResourceGroup? loading;