Build Production Buildings

Complete Build the HUD first. The Soldier will place a Barracks for 100 Minerals and a Factory for 200. Buildings take ten seconds to become operational.

Before adding buildings, make room on LVL_DemoSkirmish: scale the existing template floor to cover at least 6000 × 6000 world units, keeping its top surface at the same height. Expand the Sein Level Volume inside those edges, press Bake Level Data, and save. Keep the player start and deposits on the floor.

1. Create the Barracks

In Content/Demo/Blueprints, create a SeinARTS Entity, parent Generic Entity, named SU_Barracks. Set Display Name on Sein Identity to Barracks.

Add the following components:

Component	Configuration
Static Mesh	Engine Cube; relative Location (0, 0, 100), Scale (4, 4, 2)
Sein Vision	Default
Sein Abilities	Default
Sein Construction	Default
Sein Extents	One Box: Forward half extent 200, Right half extent 200, Height 200; Collision enabled; Mobility Static; Blocks Nav enabled
SC_DemoHealthComponent	Health 500, MaxHealth 500
Sein Production	Spawn Point Offset location (350, 0, 0)

The spawn point sits outside the building’s footprint. Runtime navigation blocking lets a placed building obstruct movement and lets its destruction clear the obstruction.

Compile and save.

2. Create the Factory

Create another Generic Entity named SU_Factory. Set Display Name to Factory.

Use the same component set with these changes:

Setting	Factory value
Cube relative Location	(0, 0, 125)
Cube Scale	(6, 5, 2.5)
Box forward/right half extents	300 / 250
Box Height	250
Health and MaxHealth	750
Spawn Point Offset location	(500, 0, 0)

Compile and save.

3. Complete construction

Create a Generic Ability named SA_CompleteConstruction. Enable Is Passive.

On Event On Tick:

1. Call Is Under Construction with Owner Entity.
2. If false, End Ability.
3. Otherwise call Add Construction Progress, Entity = Owner Entity, Amount = Delta Time.
4. Check Is Under Construction again. If false, End Ability.

This makes each building advance its own ten-second construction timer. Add Construction Progress removes the construction component when finished and releases the framework’s UnderConstruction tag.

Grant SA_CompleteConstruction on both buildings. Do not add UnderConstruction to the passive ability’s Blocked Tags: it needs to run during construction.

Compile and save all three assets.

4. Create Barracks placement

Create a Generic Ability named SA_Place_Barracks:

Field	Value
Ability Name	Build Barracks
Target Type	Point
Dispatch Mode	Single
Max Range	500
Out Of Range Behavior	Auto Move Then
Requires Free Footprint	Enabled
Resource Cost > Amounts	SeinARTS.Resource.Minerals → 100
Cancel Abilities With Tag	SeinARTS.Ability
Targeter Spec	Point + Facing Targeter Spec

Expand Targeter Spec. Set Building Class to SU_Barracks, Rotation Step Degrees to 90, and Reject Click When Blocked to enabled. The default preview reads the building’s mesh and extents.

On Event On Activate:

1. Check that Targeter Points has an element at index 0. If not, Cancel Ability.
2. Get element 0 and call Get Targeter Point Transform.
3. Call Spawn Entity with Actor Class SU_Barracks, Spawn Transform from that node, and Owner Player ID from Get Entity Owner on Owner Entity.
4. Check the returned handle with Is Entity Alive. On success, End Ability. On failure, Cancel Ability so the activation payment is refunded.

The ability’s Resource Cost takes payment. Do not add a second Deduct node to the graph.

Compile and save. Grant SA_Place_Barracks to the Soldier. Its HUD now includes Build Barracks.

5. Create Factory placement

Create SA_Place_Factory through the Generic Ability factory. Use the same settings and graph, changing Ability Name to Build Factory, resource amount to 200, Targeter Spec’s Building Class to SU_Factory, and Spawn Entity’s Actor Class to SU_Factory.

Grant it to the Soldier. In the next chapter, research will gate this ability. Compile and save.

6. Display construction progress

Add a Progress Bar named ConstructionBar to the HUD’s SelectionPanel, above ActionButtons. In RefreshHUD, use the primary view model’s Entity handle:

• If Is Under Construction is true, show ConstructionBar and set Percent from Get Construction Percent, converted with Fixed To Float.
• Otherwise collapse ConstructionBar.

These are read operations. No construction mutation belongs in the HUD.

7. Test placement

Run Play Standalone. Select the Soldier and click Build Barracks. Move the preview onto clear ground. Press the right mouse button to lock its location, drag to choose facing, and release to place it.

Check that Minerals drops by 100, the Barracks appears at the preview’s location and orientation, and selecting it shows a construction bar reaching completion after ten seconds. Build a Factory and check its 200 cost.

Try an overlapping placement and a placement outside the playable bounds. They should not produce a building or charge a completed placement. Keep space around the spawn-point side of each building.

Checkpoint

• The Soldier creates buildings through placement abilities.
• Placement validates a footprint and uses the captured transform.
• Construction advances through simulation callbacks.
• The HUD displays construction progress.

Continue with Add Production and Research.