Vitals

Documentation Unreal Engine Player Combat Vitals Health

Give a character resource pools: health that hits take, stamina that refills on its own, and any other pool you name, spent by moves, drained over time and read by a HUD.

Set it up

2 minutes

1
Find the Vitals component
The UPC Character Base carries UPC Vitals (VitalsComponent) with one row, Health at 100, which hits drain with no wiring. On another pawn, add UPC Vitals; depleted tags and events also need an ability system on that pawn.
2
Add stamina that refills itself
Press + on Vitals for a stamina row with a regeneration rate and a delay.
VitalsComponent
▾Vitals > Index [1]
Vital Tag
Max Value
Regen Rate Per Second0.0
Regen Delay Seconds0.0
15 a second, starting 1.5 seconds after anything last changed the pool.
3
Spend it on a move
On any node of your own graph, such as AG_MySword's attack from First Combo, press + on Costs and pick Vital. The Gates quick start builds a Dodge node with this cost.
AG_MySword
▾Costs > Index [ 0 ] (Vital)
Vital Tag
Amount0.0
25 stamina per use. With less than 25 left, the move does not start.
4
Play, and watch the pools
Press Play and run UPC.Debug.Vitals 1 to see each character's pools above its head. Use the move: stamina drops and climbs back.

A pool with no row reads as 0: a mistyped tag leaves a move that never runs, and a character with no Health row takes no damage. Keep that row when you edit Vitals on a Blueprint child.

Author a pool

Details

UPC Vitals

Vitals

1 Array element

Index [ 0 ]

Vital Tag

UPC.Vital.Health

Max Value

100

Regen Rate Per Second

Regen Delay Seconds

Depleted Loose Tag

None

Depleted Result Tag

None

Depleted Gameplay Event

None

Debug

Debug Overlay Vitals

Created on every character built on the UPC character base, with one Health row at 100 and no regeneration. Add a row for stamina, stance, or any other pool.

Field	Sets
Vital Tag	Which pool the row is. `UPC.Vital.Health`, `UPC.Vital.Stamina` and `UPC.Vital.Stance` ship; any tag works.
Max Value	The upper bound. The pool starts full; a row at 0 is skipped with a warning.
Regen Rate Per Second	How fast it climbs once the delay passes. 0 turns regeneration off.
Regen Delay Seconds	The wait after any change before it climbs; each change restarts it, and 0 climbs at once.
Depleted Loose Tag	A tag the character holds from the moment the pool empties until it starts to refill. Put it in a transition's Blocked Tags (Action Graph) to shut a move while the pool is spent.
Depleted Result Tag	Added to the report of the hit that empties the pool, once, as poise uses it.
Depleted Gameplay Event	Sent to the character once per emptying, to start an ability: a stance at zero staggers the character.

Spend, heal and read

Node	Does
Modify Vital	Adds or subtracts. A spend the pool cannot pay changes nothing and returns false, so one call checks and spends. A gain stops at the maximum.
Drain Vital	Takes up to the amount, stops at zero, and returns what came off.
Set Vital, Fill Vital	Set the pool, or fill it.
Get Vital Value, Get Vital Fraction	The current value, regeneration included, or 0 to 1 of the maximum for a bar. 0 for a pool with no row.
Get Vital Max, Has Vital, Is Vital Depleted	The maximum, whether the row exists, whether the pool sits at zero.

The four that change a pool run on the server. The readers work anywhere and are cheap enough to poll each frame. Neither regeneration's climb nor a drain's fall fires an event as the value moves, so a smooth bar polls Get Vital Fraction; one that redraws per hit binds On Vital Changed.

For a channeled spell, Start Vital Drain drains a pool at a steady rate and returns a handle for Stop Vital Drain. Regeneration waits for the last drain on the pool to stop, then its delay starts over.

When a pool empties

On Vital Depleted fires for any pool that empties, with its tag. With a Depleted Loose Tag set on the quick start's stamina, four 25-stamina moves empty it: On Vital Depleted fires and the tag goes on; 1.5 seconds later regeneration starts and the tag comes off.

An empty health pool leaves the character standing for your game to decide: a death belongs in On Damage Taken, whose Was Fatal marks the emptying hit (Damage and Hit Effects). Health Vital Tag in the class defaults names the pool hits drain; change it and the row together to rename it.

What reads a pool

Where	Reads it to
A node's Vital cost	Pay to run the move. A negative Amount fills the pool, for a meter built per action.
A node's Vital gate	Allow the move only while the pool meets a level, spending nothing: a finisher at full meter.
A transition's Vital Threshold condition	Choose another move while the level is not met.
A node's Drain Vital hook	Drain at Drain Rate Per Second while the node runs; End Behavior says whether an empty pool keeps it running, finishes it or cuts it.
UPC Sprint's Stamina Vital	Spend stamina while sprinting (Sprint and Speed).
A defense response's Cost Vital Tag	Charge a raised guard (Defense).

Gates, Costs and Cooldowns covers the first three in full.

Debug it

UPC.Debug.Vitals 1 writes every pool above each character, on a client as well as the server.

AdvancedDrains in detail

A drained pool stops at zero and empties as any pool does (On Vital Depleted, the Depleted Loose Tag, the Depleted Gameplay Event); the drain runs on until stopped, so the pool stays empty.
Two drains on one pool add up; stopping one leaves the other.
A tag with no row, or a rate of 0 or less, starts nothing and returns a handle naming nothing; stopping it, or a stopped handle, does nothing.
Drain Vitals takes a list of tag-and-amount rows, such as health and stance from one attack, and reports what came off each; a row naming a pool the character lacks drops out. Can Afford Vital Drain answers whether every pool holds what the list asks, rows naming one pool adding up. An attack names its extra pools in its damage config's Additional Vital Damage.

AdvancedEvery vital event

Event	Fires
On Vital Changed	On each change: a spend, damage, a set or fill, regeneration reaching the maximum. Carries the tag, the new and previous value and the maximum. A drain fires nothing until it empties the pool.
On Vital Depleted	Once per emptying, again only after the pool recovers. The Depleted Loose Tag is on when it fires.
On Vital Full	When the pool reaches its maximum.

MultiplayerWhat runs where

The server owns every value; the change nodes run there and clients receive the result.
Each change sends one record: the value, the server time it was written, and the rate running from it. Every machine extrapolates the current value against the shared server clock, so a bar stays smooth with no traffic between changes. Get Vital Anchor copies that record, for debugging and tests.
Server and clients fire the same events for the same change, whatever the latency; only the displayed value extrapolates.
Refresh Ability State puts the depleted tags back after the character's ability system appears or changes. Notify Ability System Ready, which the UPC Character Base sends, calls it; a pawn of your own with a late ability system on its PlayerState calls one of them. Repeat calls are safe.

AdvancedTroubleshooting

Nothing is spending or refilling

The tag has no row. Changes do nothing and readers answer 0; Modify Vital, Drain Vital, Set Vital and Fill Vital warn with the tag they could not find.
The call ran on a client. The four change nodes do nothing there, and Modify Vital returns false as if the pool could not pay. Spend from a server event, or let a Vital cost on a node pay on the server.
Regen Rate Per Second is 0, so the pool holds where it was left.
Something keeps touching the pool. Each change restarts Regen Delay Seconds, a Set Vital to the same value included, so a pool nibbled faster than its delay never climbs.
A drain is running. Regeneration waits until it stops.
The Depleted Loose Tag never shows. It needs an ability system on the character, and goes as regeneration starts: with a rate above 0 and no delay, the pool recovers in the instant it empties.