Open MLO Creator · All tool guides

Before you start

Start from a built-in example or draw a floorplan. Decide a unique interior name and its world position.

Step by step

  1. Choose the single-room example for a first build. Inspect the walls, opening and room before extending the plan.
  2. Set the interior name, position and yaw. Follow the inspector’s validation, including its non-zero yaw requirement.
  3. Draw walls and place doors/windows. Check rooms and openings in the preview before adding props, floors or stairs.
  4. Review Problems and fix invalid geometry. For multiple floors, check stair access and the openings above stairs.
  5. Save the design as JSON, then choose Build and download the resource.
  6. Test entrances, room transitions, collision and sound in a development server before adding more complexity.

Keyboard shortcuts and held props

Press ? or choose the Keyboard shortcuts button in the tool rail for the full list, grouped by tools, held props and selection, drawing, and camera controls. Shortcuts leave text fields and dialogs alone.

The Held chip above the canvas shows the selected prop’s current placement mode, with a surface-snap hint for a prop ready to place. Alt-drag near a wall changes a single prop to Against a wall, with a short notification naming the shortcut. This attachment stays after you release Alt. Use Ctrl/Cmd+Z after the drag to undo, or change Held in the inspector to Free or On the floor.

Placing props

Click to place a prop or drag a single prop over a table, counter or wall-mounted shelf. Its base snaps to the highest bounding-box top beneath its footprint’s centre on the current storey. Moving a stacked prop off its support returns it to the floor. Hold Ctrl (or Cmd) while placing or dragging to bypass surface snapping and keep the current height; use the inspector to set a floating height. Alt-drag still attaches a prop to the nearest wall.

What you get

A streamed interior resource, with the generated map, archetype, drawable, collision and configured audio content. The saved JSON preserves the editable design.

Troubleshooting

If Build is unavailable, review the Problems panel. If a room disappears through a doorway, inspect room boundaries and portals. If the site overlaps existing map content, review the map-removal settings and test the surrounding area.

Next steps

Read Installing and checking results before replacing a working resource. For access, failed jobs or download problems, see Troubleshooting tools.

Pick existing buildings for removal

In Map removal, load a binary .ymap from your local game files (up to 32 MB). The file is parsed in your browser. The map shows entity origins within 100 metres of your interior’s placement, with north up and the current floorplan in blue. Click a marker or use its checkbox to toggle removal; orange markers are selected. The list shows each model hash and its world coordinates.

Load additional maps, including LOD maps, to select more targets. Existing selections remain in the editable model-hide list below the picker, even after loading a different map. Save the design JSON to preserve them. Moving the interior does not move removal targets.

Build includes the selections in removal.lua, with a one-metre radius per entity; adjust individual radii in the model-hide list if needed. IPL names can also be entered below the picker, but removing an IPL affects its entire group. Entity markers are origins, not building bounds: check the model and coordinates before selecting.

Model hiding does not remove static collision or occluders. Select LOD entities separately and test the lot in game; the generated resource README explains the remaining map-editing steps when hiding is insufficient. The picker needs your source YMAP files because the terrain/building-footprint index does not contain model identities.

View placement on the world map

Choose View in game above the workspace for a north-up 2D map at the MLO’s world coordinates. Blue outlines show the rooms across all storeys; the dashed outline includes the ground shell’s wall thickness. Grey bounds show nearby GTA building pieces from the game’s building corpus. The origin, front direction, position and rotation help you check the placement before building. Use Zoom in and Zoom out to inspect the site, and edit Position and rotation in the inspector to refresh the map automatically.

The overlap message checks the ground shell bounds against nearby building bounds. This is an approximate siting check, not a collision test: upper storeys, terrain, roads and surrounding textured 3D geometry are not checked by this view. Up to 60 nearest building pieces are shown within 200 metres of the shell bounds; the overlap check also considers pieces beyond that display limit. Confirm the final placement in game.

For shells wider or deeper than 400 metres including walls, the map still shows the MLO placement but explains that nearby-building and overlap checks are unavailable at that size.