Getting Started with Universal Player Combat

Documentation Unreal Engine Player Combat Tutorial

Turn Universal Player Combat on, play the demo map and land a hit with a sword off the rack, then build on the demo player or remove the demo when you no longer need it.

Set it up

5 minutes

1
Turn the plugin on
Get Universal Player Combat on Fab and click Install to Engine in the Epic Games Launcher (5.6, 5.7 or 5.8). In your project, open Edit > Plugins, tick it and restart. The engine plugins it needs switch on with it and its gameplay tags register themselves: no collision channels, surface types or tag files to set up.
2
Open the demo map
Turn on Show Plugin Content in the Content Browser's settings, then open Demo/Maps/LVL_UPC_Demo.
LVL_UPC_Demo
▾Game Mode
GameMode OverrideNone
Set in the demo map's World Settings. For a level of your own, set it there or as the Default GameMode in Project Settings > Maps & Modes.
3
Take a sword
Press Play and walk down the hallway to the weapon rack on your left. Look at a sword and press E: it goes on belt slot 1 and into your hand. 1 puts it away and draws it again.
4
Hit a training dummy
The two training dummies stand on the right, a few steps back. The left mouse button is a light attack (click again during each swing for a three-hit combo), the right a heavy one. The dummies cannot die; the right one adds sparks and a short pause on each hit.

Keys

Action	Keyboard and mouse	Gamepad
Move, look	W A S D, mouse	Left stick, right stick
Light attack	Left mouse button	Right shoulder
Heavy attack	Right mouse button	Right trigger
Guard: a sword parries on a press as the hit lands and blocks while held; a shield rises	Q	Left trigger
Lock on, then flick sideways to switch target	Middle mouse button, then the mouse	Top face button, then the right stick
Dash: a dodge with a weapon, a vault over an enemy with bare fists	Space	Left shoulder
Interact, and the second option (kick, break)	E, F	Bottom face button, left face button
Draw or put away a belt slot	1 to 4	D-pad
Drop what is in hand	G	Right face button
Open the inventory	I	Tap View
Sprint (hold)	Left Shift	Left stick click
Swap the camera shoulder	V	Right stick click
Jump to the start, the paired actions, the style plates	7, 8, 9	Hold the right special button, press the D-pad up, right, down

On the Freeflow style plate (below), the right mouse button guards instead, and a guard on a punch showing the counter marker counters it.

What the demo shows

Stop	Try	Open
Door	E opens it, F kicks it open	`BP_UPC_Door`
Training dummies	The right one has a defense set of its own	`BP_UPC_HitDummy`, `DefenseRuleSet_UPC_HitDummy`
Chests	E opens a chest, F breaks the lid off	`BP_UPC_Chest`
Loot chest	E opens your inventory beside it on a style that has a screen (switch at the wardrobe's style pads first), F takes everything that fits	`BP_UPC_LootChest`
Places on the Body	Two figures draw and sheathe two swords, and a sword and shield	`BP_UPC_EquipmentShowcase`
Weapon rack	E takes a sword or the shield, or puts a sword back on an empty peg	`BP_UPC_WeaponRack`
Paired actions	Six stations loop executions, counters and a vault; step onto the ring marked (you) and press E	`BP_UPC_PairedStation`, `Paired_UPC_*`
Style plates	Over Shoulder (sword and shield), Freeflow (bare fists), Soulslike (two swords), each with its arena; a red plate brings you back	`BP_UPC_StylePlate`, `Demo/Combat/Styles`
Wardrobe plate, in the start room	A pad for each weapon and worn item, and pads that switch the inventory style	`LVL_UPC_Wardrobe`

The arenas

Arena	Enemies	What it shows
Over Shoulder	Three bosses with a two-handed baton, one attacking at a time	Block, parry, a shield bash, telegraphed swings
Freeflow	Four weaker enemies, two attacking at once	Strikes aimed with the stick, a dash strike at range, a counter on a punch showing the counter marker, a vault over an enemy
Soulslike	One boss with a two-handed baton, picking its swing by your distance. After 250 damage it stays stunned until you walk up and press Light Attack, and only that sword execution kills it	Lock-on, parry and block with two swords, a finisher

The enemies are built on UPC Character Base and run action graphs pressed by a Behavior Tree: the Freeflow crowd uses the player's unarmed graph, the bosses the baton's. They take turns through an attack token pool per arena (BP_UPC_AttackTokens). Patterns walks through their moves.

Build on the demo player

Duplicate BP_UPC_Character (Demo/Characters/Player) and swap its mesh and Animation Blueprint. The demo's moves fit the demo mannequin's skeleton, so another skeleton needs animations of its own and the Animation Blueprint needs the Slot nodes the montages play in (The Animation Blueprint). A character with its own parent class follows Character Setup.

Where	Setting	Value
Class Defaults	Starting Ability Set	An asset listing abilities and their input bindings; the demo's `AbilitySet_UPC_Default` holds lock-on, interact, sprint, drop, item use, and the demo's hit reactions
Equipment Manager	Default Item	`Item_UPC_Unarmed`, the fists it fights with when nothing else is drawn
Equipment Manager	Body Places	Main hand `hand_r`, off hand `hand_l`, three sheaths on the back
Inventory	Config	`InventoryConfig_UPC_Simple`: it carries what the belt holds and the gear it wears, and opens no inventory screen; no Starting Items
Combat	Style	`CombatStyle_UPC_OverShoulder`
Targeting	Targeting Config	`TargetingConfig_UPC_OverShoulder`
Vitals	Vitals	Health, Stamina and Stance (a pool whose emptying staggers the character), each 100 and refilling 10 a second after 3 seconds (Vitals)
Team	Team Id	0; the demo's enemies are on 1
Mesh	Component Tags	`UPC.Montage`, `UPC.Attachment.Body`

BP_UPC_PlayerController, a UPC Player Controller, carries the belt (a UPC Quick Bar of four slots that takes new items and draws them), the shared keys (IMC_UPC_Default), the HUD and the inventory screens. BP_UPC_GameMode names both classes. To play your duplicate, duplicate BP_UPC_GameMode, set its Default Pawn Class to your character, and set it as the level's GameMode Override.

The demo map's Level Blueprint (Blueprints > Open Level Blueprint) holds one comment box per system of unconnected example nodes to copy.

Removing the demo (optional)

The Demo folder is optional. Keep it to learn from, or remove it once nothing of yours uses it. The plugin's Core folder holds everything it needs to run. With the plugin installed to the engine, every project on that engine shares the Demo folder, so leave it in place there.

Untick Load Demo Hit Effects in Project Settings > Plugins > Universal Player Combat Demo. It loads the demo's sparks, sounds and camera shakes; hit stop plays without it. It takes effect on the next start.
Right-click each of your assets built from the demo (your character, game mode, items and levels) and open the Reference Viewer: each asset it lists under Demo is one your asset still references. A duplicate of BP_UPC_Character, for one, still points at the demo assets in the table above, such as AbilitySet_UPC_Default and Item_UPC_Unarmed.
Duplicate each of those into your own folders and point your asset at the copy. A copy can point at demo assets of its own (your character, then its item, then the item's action graph, then the graph's montages), so repeat until the Reference Viewer shows nothing under Demo.
Last, delete the Demo folder.

Debug it

UPC.Debug.All 1          // Every overlay above every character; UPC.Debug.All 0 clears them
UPC.Debug.Actions 1      // The node each character is in, its window, a press waiting
UPC.Debug.Equipment 1    // What each character holds, which item drives combat, what it carries
UPC.Debug.Targeting 1    // Who each character fights, and each candidate's score
UPC.Debug.Interaction 1  // What the character can use, and the option a press would run
UPC.Debug.Vitals 1       // Every pool against its maximum
UPC.Logs Verbose         // Every log category; UPC.Logs alone puts back warnings only

AdvancedMore debug switches

UPC.Debug.WatchPawn <name> narrows every overlay to one character, part of a name being enough; UPC.Debug.WatchClear puts them all back.
UPC.Debug.MaxDistance sets how far from the camera a character still draws (4000 cm), and UPC.Debug.TextScale sizes the text.
UPC.Debug.Melee.DrawTracing 1 draws every weapon sweep, and UPC.Debug.Steering.Draw 1 where each attack steers.
The plugin logs only warnings, each naming a setup mistake and its fix; Log LogUPCInventory Verbose raises one category.

AdvancedWhat the demo player is made of

Components

+ Add

BP_UPC_Character (Self)

Capsule Component

Arrow Component

Mesh

SpringArm

Add

TPSCamera

Add

Character Movement

Equipment Manager Component

Inventory Component

Action Graph Component

Melee Trace Component

Input Mapping Component

Anim Manager Component

Vitals Component

Defense Component

Targeting Component

Targetable Component

Team Component

Approach Component

Combat Component

Interactor Component

Anim Effect Component

Ability System Component

UPCSpeedModifier

Add

UPCPhysicalReaction

Add

UPCTelegraphViewer

Add

MotionWarping

Add

UPCStowVisual

Add

UPCCameraRig

Add

Sprint

Add

Grayed rows come with the engine's Character and UPC Character Base; the rest is what the demo Blueprint adds.

Character Setup says what each of the base's components does. The base moves with UPC Character Movement, which keeps a player's corrections smooth under lag, and answers hits itself: its defenses resolve the hit and the rest comes off its health. Override On Damage Taken in a Blueprint child for a flinch or a death (Damage and Hit Effects). Its Class Defaults:

Setting	Default	Does
Starting Ability Set	None	Abilities the character has from the start, bound to their keys on the player's machine. Weapon moves belong on the item.
Draw Starting Items	on	Draws the inventory's equippable items into the hands, unless the controller's belt has Auto Populate from Inventory on and takes them.
Ignore Camera Collision	on	Keeps a camera from zooming in when this character walks between it and the player it follows.
Health Vital Tag	`UPC.Vital.Health`	The pool a hit takes its damage off.

Its Vitals start with a Health row of 100 and its Team Component on no team (255) until you set Team Id.

MultiplayerAn ability system on the PlayerState

The demo keeps each character's ability system on the character, in Mixed replication mode. To keep a player's abilities across deaths and respawns, host it on the PlayerState:

Write a PlayerState in C++ that implements IAbilitySystemInterface and creates a replicated ability system component in Mixed replication mode. Raise its Net Update Frequency (100 works); the engine's default is low.
Set the game mode's Player State Class to it.

A character built on UPC Character Base uses a PlayerState's ability system in place of its own, granting its abilities on possession and taking them back when it ends. The PlayerState needs C++ because Blueprint cannot implement the interface. Get Ability System Component Internal, overridable in a Blueprint child of the base, points the character at an ability system kept elsewhere.

C++C++

AUPCCharacterBase (UPCGame) is Abstract and Blueprintable, derives from ACharacter, and implements IAbilitySystemInterface and IUPCDamageable.
InitializeAbilityActorInfo (virtual, protected) runs from PossessedBy on the server and OnRep_PlayerState on clients: it calls InitAbilityActorInfo(Owner, this), grants the Starting Ability Set and sends UUPCAbilitySystemReady::NotifyAbilitySystemReady. NotifyControllerChanged calls RefreshAbilityActorInfo(), which a PlayerState-hosted system needs since a client can receive the PlayerState before the controller.
GetAbilitySystemComponentInternal (BlueprintNativeEvent) resolves the ability system, PlayerState first; OnDamageTaken (BlueprintNativeEvent, authority only) and ResolveIncomingHit are the damage seams.
A C++ child that moves with a movement component of its own passes its class to the protected constructor AUPCCharacterBase(const FObjectInitializer&, TSubclassOf<UCharacterMovementComponent>).
AUPCPlayerController creates the UUPCQuickBarComponent and calls InitializeForPawn from OnPossess and OnRep_Pawn.