Attack Steering

Documentation Unreal Engine Player Combat Attack Steering

Attack Steering makes an attack turn to its target, close the gap and stop short of it instead of running into it, through windows you mark on the montage and the UPC Attack Approach component.

Set it up

5 minutes

1
Mark the wind-up on an attack montage
Open an attack montage animated on the spot, with no root motion. On a notify track, right-click at the wind-up's start, pick Add Notify State > UPC Approach Window, and drag its end to where the swing begins: the start of the montage's UPC Melee Trace Window, the window that sweeps the weapon for hits (Melee Trace). Leave Approach Target Name on Target.
AM_MyAttack
0.0
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0.8
1.0
1.2
Notifies
UPC Approach Window
UPC Melee Trace Window
The approach window covers the wind-up; the character arrives as the swing begins.
2
Play it from the action graph
Put the montage on a node's Play Montage payload in the character's action graph (Action Graph). An attack takes its target as its node starts and steers only from an action graph node.
3
Check that the style steers
In the character's combat style (Combat Styles), the Targeting fragment needs a Targeting Config and Steering on Toward Target, its default. The style writes to the ApproachComponent and TargetingComponent UPC Character Base carries; add UPC Attack Approach and UPC Targeting to any other character.
CombatStyle_MyStyle
▾Fragments, Index [ 1 ]: Targeting
SteeringDistance Only
4
Press Play and attack from a few steps away
Stand about 3.5 m from an enemy, such as the dummy from the Targeting quick start, and attack: the character turns toward it, glides in over the wind-up, and swings the stop distance short of it. The stop distance is 150 cm, the component's default since this style has no Approach fragment, unless the drawn weapon or the window sets its own (order); the demo's bare hands stop 25 cm short.

Pick how attacks steer

Three separate controls shape an attack: Attack Facing turns the body as the attack starts, Steering (set by the style's Targeting fragment on the UPC Attack Approach component) decides whether the attack closes on its target, and Keep Distance stops its travel short of enemies. Each works without the others.

Plays where it was aimed. The swing travels its own 160 cm and lands beside the target.

Turns to the target and closes in, landing the stop distance short of it.

Goes where the body faces, as animated, and stops short of the enemy its path runs into. The target off to the side is left alone.

Seen from above, the character starting at the dashed circle and facing up the page. The dashed ring marks the stop distance around the body an attack stops short of; blue is where the attack ends and the arrow the way it faces.

Toward Target (default) glides each attack in through a UPC Approach Window or warps it through a UPC Skew Warp, both set up below. Distance Only and Off keep the animation's own travel; Distance Only also warps a dash to the gap (Distance Only and gap closers), Off warps nothing. Steering Off leaves the other two controls running: with Attack Facing Aim and Keep Distance on, the body still snaps to the camera's aim as the attack starts (Attack Facing) and the attack's travel still stops short of an enemy in its path (Keep Distance).

An attack keeps the target it took as it started (the Targeting pick or the held lock); each hit of a combo picks again.

Close the gap on a swing animated on the spot

Drag a UPC Approach Window across the wind-up. While it runs, the character turns toward the target and glides into range; a target already in range only turns it.

Details

UPC Approach Window

Approach

Move by Offset

Offset Direction

-1.0

0.0

Offset Distance

Approach Target Name

Target

Mode

Move and Face

Advanced

Stop Distance Override

-1

Max Approach Distance Override

-1

Facing Interp Speed Override

-1

Facing Speed by Angle Override

None

Override Speed Limit

Speed Limit Override

Unlimited

Max Approach Speed Override

600

Override Block Movement Input

Block Movement Input Override

Override Moving Target

Moving Target Override

Lead

Lead Strength Override

-1

Time Mapping Curve Override

Curve_UPC_EaseInOut

The two-handed attack's window, which eases its glide in and out. Every override left at -1 or unset takes the UPC Attack Approach component's matching Default; Stop Distance Override falls to the weapon's Attack Stop Distance first.

Setting	Does
Approach Target Name	Keep `Target`, the name the component stores the attack's target under. A Motion Warping window uses a different name, `UPCTarget`, below.
Mode	Move and Face (default), Face Only to turn without moving, Move Only to glide without turning.
Move by Offset	Moves Offset Distance along Offset Direction, in the character's own space, instead of steering: a step back on a block.
Stop Distance Override, Max Approach Distance Override	How far short this attack stops, and the farthest target it glides to. A value left at -1 falls through: for Stop Distance, the drawn weapon's Attack Stop Distance, else the style's Approach fragment default (the component's without one); for Max Approach Distance, the style's default (order). The attack's own Stop Distance on its Play Montage node wins over the window's.

Step forward at nothing

A UPC Approach Or Move Window with no target in reach moves Move Distance (50 cm) along Move Direction (ahead) instead, so a punch at empty air still lunges.

Details

UPC Approach Or Move Window

Approach

Move Direction

1.0

0.0

Move Distance

Its other fields are the UPC Approach Window's. Move Direction and Move Distance gray out under Move by Offset and under Face Only.

Close the gap on a swing with root motion

Give the character a Motion Warping component.
Add the engine's Motion Warping notify state across the stretch of the montage that travels.
Set its Root Motion Modifier to UPC Skew Warp and its Warp Target Name to UPCTarget.

Motion Warping

▾Config

Root Motion Modifier

Warp Target NameNone

Stop Distance Override

The UPC Skew Warp lands the stop distance short of the target, facing it; Stop Distance Override sets the distance for this window.

Distance Only and gap closers

Pair Distance Only with Attack Facing set to Aim, so each attack first turns to where the camera looks. An enemy beside the path or behind the character does not stop it.

A dash closes the gap through a UPC Gap Closer Warp as its Motion Warping window's Root Motion Modifier (Warp Target Name UPCTarget): it lands the stop distance in front of the first enemy the body's facing line runs into, or plays its own travel with none on the line. Under Toward Target it lands as a UPC Skew Warp does; under Off it warps nothing.

Keep Distance: stop short of enemies

Keep Distance, on for the UPC Attack Approach component, stops the character's travel the stop distance short of its target and of any targetable enemy in its path, whether the travel comes from root motion, a warp or a glide; the animation plays on. The enemies are those the Targeting Config's scan finds and its Target Teams admits. A move toward an enemy already that close holds; a move away or past it goes through. Only attack montages stop: one with a UPC Melee Trace Window, an Approach Window on Target, or a UPC Skew Warp or UPC Gap Closer Warp window. A dodge or a hit reaction plays as authored.

Make Room steps an attack back first when it starts closer than the stop distance to the enemy it aims at: the character moves straight back to the stop distance over the style's Make Room Seconds, and Keep Distance holds the swing there. That enemy is the target the attack steers at under Toward Target, else the targetable enemy deepest inside the stop distance that the facing line runs into. A wall or another body behind cuts the step short, the enemy never moves, and the body keeps its facing. Make Room Seconds starts at 0, off; the demo's Freeflow and Over Shoulder styles use 0.15. A move's own Make Room Seconds on its Play Montage node takes over for that attack: 0 turns the step off, above 0 turns it on under any style.

Where the stop distance comes from

Asked firstAsked last

The move

Stop Distance on the attack's Play Montage node, under Spacing

Counts at 0 or more, for the whole attack. -1, the default, passes the choice down. The demo's shield bash keeps 25 cm with the sword drawn.

The window playing right now

Stop Distance Override on a UPC Approach Window, UPC Approach Or Move Window, UPC Skew Warp or UPC Gap Closer Warp

Counts at 0 or more. -1, the default, passes the choice down. When two windows cover the same moment, the one that started later counts.

The weapon in hand

Attack Stop Distance on the item's Equippable fragment

Read from the item whose moves the character is using. -1, the default, passes the choice down. The demo's bare hands stop 25 cm short.

The combat style

Stop Distance on the style's Approach fragment

Written onto the UPC Attack Approach component's Default Stop Distance as the style applies. 150 cm when nothing sets it.

The same distance serves the glide, the warp's landing and Keep Distance, measured between the two capsules.

With a style at 150, a sword at 100 and a last hit whose window sets 0, the first hits stop 100 cm short and the last reaches contact; a window's override counts only while it plays. A move's own Stop Distance counts for the whole attack, so give a short move beside a long weapon its own: the demo's shield bash, drawn beside the sword, keeps 25 cm rather than the sword's 75.

Turn the body as an attack starts

Attack Facing, set by the style's Rotation fragment (Aim, Movement, Lock Target or None), snaps the body as an attack starts, when the section being played carries a UPC Melee Trace Window, an Approach Window or a Motion Warping window on UPCTarget. With Attack Facing on Aim, Steering on Toward Target and an enemy left of the camera's center, one attack runs:

It starts: the body snaps to the camera's aim, or to a held lock.
Its Approach Window plays: the body turns toward the target and glides in.
It swings: the body keeps the facing the window left, whatever the stick does, until the combo's next hit takes over.

Debug it

UPC.Debug.Steering.Draw 1    // Warps in green, approach windows in orange, a ring at the stop distance
UPC.Debug.Approach 1         // The approach above each character; each window's decision and each attack's stop distance, with its source, in the log
Log LogUPCApproach Verbose   // The rest of the approach log

Debug Overlay Approach on one component shows that character alone.

AdvancedGlides in detail

Moving Target: Lead (default) aims where the target is heading, smoothest against a strafing enemy; Chase where it stands; Committed where it stood as the window opened, missing a target that stepped away. Lead Strength (1) sets how far ahead Lead aims.
Speed Limit: Unlimited (default) spreads the distance across the window, so a large gap closes in a blink and a short one at a crawl. Fixed Speed travels at Max Approach Speed (600 cm/s) and lands short of a target too far for the window. Character's Max Speed reads like running.
A window on a root motion swing makes up only the ground the swing falls short by; on a player's character, prefer Motion Warping there.
A glide leaves height to gravity and closes on a higher target from the side; give an attack that should leap root motion or a warp.
On the server a player's target can land after a window opened; the window then steers at it from where the character stands, taking over from an Approach Or Move Window's step.
Report Glide as Movement Input (on) hands a glide's direction to the movement input, so the animation graph plays a walk or a run.
Ease Facing Back turns a camera-following body back to the camera after an attack lets its facing go, at Facing Hand Back Rate degrees per second (0: the character's own turn rate).

AdvancedHow an attack takes its target

A section with only a UPC Melee Trace Window turns and keeps its distance, and steers at no one.
Under Distance Only an attack takes the first targetable enemy its facing line runs into, else the soft target, passing over a dead enemy.
A body Keep Distance has counted keeps counting until the montage ends, even limp, so a killing blow's follow-through does not run into it.
On Attack Turned fires with the turn in degrees, positive to the right, for an Animation Blueprint to hide a large snap behind a root offset blended out over about a tenth of a second.
Compute Warp Transform answers where a warp lands; override it in a child class for a landing rule of your own, such as a flank. Get Effective Stop Distance reads the stop distance in force, and Get Steering Target the target an attack steers at.

AdvancedThe UPC Attack Approach component

Details

ApproachComponent

UPC

Approach

Attack Steering

Steering Mode

Toward Target

Attack Facing

None

Make Room Seconds

Warp Target Name

UPCTarget

Approach Target Name

Target

Defaults

Default Stop Distance

150

Default Max Approach Distance

750

Default Facing Interp Speed

Default Facing Speed by Angle

None

Default Time Mapping Curve

None

Speed Limit

Unlimited

Max Approach Speed

600

Moving Target

Lead

Lead Strength

Report Glide as Movement Input

Block Movement Input

Ease Facing Back

Facing Hand Back Rate

Keep Distance

Debug

Debug Overlay Approach

At its defaults. A combat style writes Steering Mode (Targeting fragment), Attack Facing (Rotation fragment), Make Room Seconds and the Defaults (Approach fragment) as it applies.

Its windows match Warp Target Name (UPCTarget) and Approach Target Name (Target) and fall back to its Defaults, which the style's Approach fragment writes. Without a Targeting component it still turns attacks as Attack Facing says and steers nothing.

The demo

AM_UPC_Unarmed_Combo carries an Approach Or Move Window on every punch (glides to an enemy within 4 m, else steps 40 to 65 cm); AM_UPC_Sword_Combo a UPC Skew Warp window per hit; AM_UPC_Unarmed_Strike_Dash a UPC Gap Closer Warp.
Freeflow steers Toward Target, Over Shoulder Distance Only with Attack Facing Aim, and Soulslike Off.

MultiplayerSteering in multiplayer

A player's attack sends its target and the body's facing with the attack, and the server steers it the same way. Between attacks the server steers at the target the player last reported.
Steering Mode, Attack Facing and the Targeting Config do not replicate. Set Steering Mode and the config on every machine (another player's view stops an attack where the server did only under the same values) and Attack Facing on the server and the player's machine; a style's fragments on Every Machine do both. The server turns the body only when its own Attack Facing says to, then takes the facing the player sent.
Keep Distance runs on the server, the player's machine and the copies others show, and the server sends the copies the attack's target, so against a still target all stop in one place. Against a target moving along the attack line, stops differ by its speed over a round trip.
An attack whose start reaches the server late, after a lost packet, starts the server's glide late, and the player can see one correction toward it.
A move's own Stop Distance is read on the player's machine and the server. Another player's view of the character stops that attack at the distance -1 would give and follows the server's position updates.
Make Room: the player's machine predicts the step back with the attack, and the server works out its own by the same rule. While the step runs, the character base's UPC Character Movement has the server take the player's stepped position, so an attack reaching the server late does not pull the player back toward the enemy. Make Room Seconds does not replicate; the style's Approach fragment on Every Machine sets it on both.

C++C++

UUPCAttackApproachComponent subclasses UUPCApproachComponent and turns KeepDistance on. It answers the drawn weapon's Attack Stop Distance through GetFallbackStopDistance() (read through IUPCAttackReachProvider, which the equipment manager implements) and the Targeting component's candidates through GatherKeepDistanceBodies().
An action graph node's ability pins its attack through IUPCActionSteeringProvider::PinAttack, handing it the move's Stop Distance, Make Room Seconds and turn to the stick in FUPCAttackPinOptions, and lets it go through ReleaseAttackPin; the ability finds the component with FindComponentByInterface.
ComputeWarpTransform is a BlueprintNativeEvent (ComputeWarpTransform_Implementation(AActor* Target)).
The Approach Or Move Window answers the approach's GetMoveWithoutTarget(FVector&, float&); a window subclass of your own can answer it the same way.

AdvancedTroubleshooting

When an attack does not steer

Symptom	Cause
No turn and no glide.	Steering is Off, the config picks no target, the attack plays from an ability rather than an action graph node, or the window's name differs from the component's.
A turn but no glide.	The target stands beyond Max Approach Distance, or the window's Mode is Face Only.
A root motion attack overshoots or spins.	The warp is the engine's Skew Warp, its name is not `UPCTarget`, or the character has no Motion Warping component.
It stops too far away.	The move's Stop Distance, a weapon's Attack Stop Distance or a window's Stop Distance Override exceeds the style's Stop Distance.
A short move beside a long weapon backs off and misses, such as a shield bash beside a sword.	The move takes the weapon's Attack Stop Distance; set the move's own Stop Distance on its Play Montage node.
It slides into the enemy.	The enemy's UPC Targetable is missing or off, its capsule lets characters through, or the character has no Targeting Config.
A Distance Only dash plays its own travel.	Its warp is a UPC Skew Warp, or no enemy stands on the body's facing line.