Add a new building type

Add a new placeable building by duplicating an existing in-game child of BP_CBT_BaseResidential or BP_CBT_BaseCommercial, then registering it in the building picker UI.

Inheritance

flowchart TB
  Base[BP_CBT_BaseBuilding]
  Res[BP_CBT_BaseResidential]
  Com[BP_CBT_BaseCommercial]
  House[BP_CBT_House]
  Apt[BP_CBT_Apartment]
  Shop[BP_CBT_Shop]
  Office[BP_CBT_OfficeBuilding]
  New[BP_CBT_YourBuilding]
  Base --> Res
  Base --> Com
  Res --> House
  Res --> Apt
  Com --> Shop
  Com --> Office
  Res --> New

Example — add a park (residential-flavoured)

Goal: a cheap decorative residential building that adds a small population bump without commercial income.

1. Duplicate the parent

1. In Content Browser, navigate to Blueprints/Buildings/InGameBuildings/Residential/.
2. Duplicate BP_CBT_House → rename BP_CBT_Park.
3. Open BP_CBT_Park and confirm parent class is BP_CBT_BaseResidential.

2. Set class defaults

Property	Example value	Notes
BuildingName	Park	Shown in UI
BuildingDescription	Short flavour text	Also add to ST_CityBuilderTemplate for localization
BuildingIcon	Your texture asset	256×256 recommended
BuildingMeshes	Single static mesh	Or array for variants
BuildingCost_Currency	Lower than House	Read house default, then reduce
ConstructionTime	5–15 seconds	Fast placement
UnlockLevel	1	Available immediately
bSpawnAmbientLights	false	Optional for parks

Assign mesh SM_ asset under Meshes/Buildings/ (import or reuse).

3. Population timer

BP_CBT_BaseResidential uses Inhabitant Add Delay and Inhabitant Max Limit (shipped House defaults: delay 2 s, max 4) with TimerHandle_AddInhabitant to call AddPopulation after construction.

• Open the Event Graph on BP_CBT_Park only if you need custom population timing.
• Otherwise set Inhabitant Add Delay / Inhabitant Max Limit on class defaults and inherit parent timer behaviour.

4. Register in the building picker

BP_CBT_PlayerController → Class Defaults lists spawnable buildings in two arrays (verified in v1.7):

Array	Shipped entries
Residential Buildings	BP_CBT_House, BP_CBT_Apartment
Commercial Buildings	BP_CBT_Shop, BP_CBT_OfficeBuilding

1. Open BP_CBT_PlayerController → Class Defaults.
2. Add BP_CBT_Park to Residential Buildings (or the commercial array for a shop-style building).
3. Open WBP_BuildingSelect and mirror the new entry in the UI list (typically ST_BuildingSelect rows tied to the same classes).

5. Save data

BP_CBT_SaveGame → AddBaseResidentialSaveValues must recognize the new class.

• If you only changed defaults on a BP_CBT_BaseResidential child, existing save functions usually work.
• If you added custom variables, extend ST_BaseResidentialSave and OnBuildingSave on your Blueprint.

6. Test

flowchart LR
  Pick[WBP_BuildingSelect] --> Preview[GetPreviewBuilding]
  Preview --> Place[Internal_StartConstruction]
  Place --> Save[OnBuildingSave]
  Save --> Load[Internal_LoadGame]

1. Play DemoMap.
2. Select Park, place on a road-adjacent cell.
3. Confirm construction, population, save, and reload.

Example — add a café (commercial)

Duplicate BP_CBT_Shop instead:

Property	Café tweak
Revenue Per Worker	Between shop (268) and office (1240) values
Profit Delay	Between shop (60 s) and office (120 s)
Worker Max Limit	Match or exceed shop (10)
bAutoCollectIncome	false for manual collect gameplay
Currency Collect XP	Slightly higher than shop (3)
UnlockLevel	2 (same as shipped shop)

Update ST_CityBuilderTemplate with ShopDescription-style entry for localized name.

Commercial vs residential checklist

Concern	Residential	Commercial
Parent class	BP_CBT_BaseResidential	BP_CBT_BaseCommercial
Primary reward	AddPopulation (via Inhabitant Max Limit)	CollectIncome (Revenue Per Worker × workers)
Save struct	ST_BaseResidentialSave	ST_BaseCommercialSave
UI tab	Residential on WBP_BuildingFrame	Commercial tab
Widget	—	Optional CurrencyWidgetButton

Next

• Customize roads and grid
• Blueprint reference — In-game building classes