BuildingFloorCoordDict

Controls the building footprint shown during, and after, construction - relative to the respective image file (e.g. buildingfloor_201_L1.png and buildingfloor_201_L2.png).

The X and Y values note the building entrance tile.

Note that some buildings (BoatYard, Harbour, Large Harbour, FishingHut, probably any building using PIER - "layerTypeToCreate": 3) will ignore buildingFloorCoordDict.
Example entry in render.json

{
  "buildingFloorCoordDict": {
    "201": {  // building ID
      "LEVEL_1": {  // building level 1
        "x": 1, // x coord of entrance
        "y": 0 // y coord of entrance
      },
      "LEVEL_2": {  // building level 2
        "x": 0, // x coord of entrance
        "y": 0 // y coord of entrance
      }
    }
  }
}

Building footprints are 128 x 128 pixels for each tile with 0,0 being in the top left.
buildingfloor_201_L2.png would contain the floor for building of ID=201 at level=2.