Prefab files

A scene can refer to a reusable object stored in prefabs/crate.glb inside the game folder. Keep exactly one root in that file. On an empty scene object, set the string custom property prefab_file to prefabs/crate.glb. Paths are relative to the game folder, including references inside another prefab. Symbolic links and paths outside the game are refused.

Loading replaces the empty object's content with the prefab root's content. The placement keeps its name, identity and parent. Its transform combines with the source root's transform. Its custom properties override the source root's properties; its existing children remain. Descendants come from the file. Geometry, materials and images are shared by repeated instances of the same file.

A source root marked prefab = true becomes live when placed. Mark the reference itself prefab = true to keep an inert template for Scene.spawn instead. Each scene load reads the current files; changing a prefab does not update a running scene.

Descendant identities are deterministic for the source file path, placement identity and source node identity. Renaming a source node preserves an explicit identity; renaming the prefab file changes the generated descendant identities. Root placement identities remain unchanged.

Animate descendants rather than the source root. Imported clips are named prefabs/crate.glb::Idle, for example. Repeated instances share that clip's name; per-object animation playback still affects only that object's hierarchy. Animated placements require an identity transform on the source root.

Cycles and oversized expansions fail the load before replacing the running scene. Defaults allow 64 source files, eight nested references, 4,096 instances and 100,000 expanded nodes, with 256 MiB of source GLB files and 512 MiB of estimated expanded content. The GLB reader also checks a tighter memory budget before reading buffers.

This first implementation supports runtime loading, editor Play and project checks. The editing viewport still shows the authored reference node. Creating prefab files, placing them through the editor and previewing inherited children are separate editor work; save the source file through your modeling tool for now. Built games include regular files in prefabs/ along with the other game assets.