After loading a level, open Edit → Material Mappings to launch the mapping editor. It manages named sets of From → To material remaps stored in the level's WORLD/MATERIAL_MAPPINGS.PAK.
Material remappings are applied to composite instances (via the mapping parameter — use Select in the entity inspector, or open this window as a picker with Select Set). That remaps materials on ModelReference entities within that instance's immediate child composite — without editing the materials themselves.
Note: currently only the mappings are previewed in the editor. They are not yet saved and respected by the game at runtime — support for that is coming soon.
This is separate from the Material Editor, which edits a material's samplers, features, and shader parameters.
The left tree lists mapping sets for the loaded level. Names with / show as folders.
Click Add New Set, enter a unique Name:, then OK to create an empty set. There isn't a rename or delete-set action in the editor — only add sets and edit the rows inside them.
When the window is opened as a picker, Select Set returns the currently selected set to the caller.
Select a set to show its mappings in the From / To list on the right. Remaps apply when material names match exactly (case-sensitive).
Edits apply in memory immediately; connected Viewport views can update without waiting for a disk save.
The mapping editor has no separate Save button. Persist changes with File → Save Level (Ctrl+S), which writes WORLD/MATERIAL_MAPPINGS.PAK (or the patched-level equivalent under _PATCH).
Saving closes the game if it's running so install files aren't locked.
