Integrating TerraInk into a fresh Lyra project.

• UE 5.6 or newer (5.8 recommended, used during plugin development).
• Lyra Sample Game source available. LyraGame module compiles cleanly before any TerraInk edits.
• Engine-side plugins TerraInk depends on are enabled: Niagara, PCG, PCGFastGeoInterop, FastGeoStreaming. The TerraInk .uplugin already declares them.

Copy the entire TerraInk folder to:

<YourProject>/Plugins/TerraInk/

The plugin ships six modules:

<YourProject>.uproject does not need a manual edit; the plugin registers itself when the engine scans Plugins/.

Open Source/LyraGame/LyraGame.Build.cs and add "TerraInk" to PublicDependencyModuleNames:

PublicDependencyModuleNames.AddRange(
    new string[] {
        // ...existing entries...
        "TerraInk",
    }
);

This is the only Lyra-side build dependency required. The other TerraInk modules (TerraInkPCGBridge, etc.) load themselves; LyraGame only needs the runtime module.

4a. Header: add three authored fields

In Source/LyraGame/Weapons/LyraGameplayAbility_RangedWeapon.h:

#include <TerraInkTypes.h>   // up with the other includes

// inside the class, in the public block
UPROPERTY(BlueprintReadWrite, EditAnywhere, Category="Lyra|Net Paint")
float PaintRadius = 289.f;

UPROPERTY(BlueprintReadWrite, EditAnywhere, Category="Lyra|Net Paint")
ETerraInkPaintLayer PaintLayer = ETerraInkPaintLayer::PaintLayer_R;

UPROPERTY(BlueprintReadWrite, EditAnywhere, Category="Lyra|Net Paint")
float PaintIntensity = .15f;

PaintLayer is the fallback layer used when the avatar is not on a team (solo / no-team modes). Team-tagged avatars override it at runtime.

4b. Cpp: includes

Near the top of LyraGameplayAbility_RangedWeapon.cpp:

// TerraInk: weapon impact painting
#include <TerraInkSubsystem.h>
#include <TerraInkTypes.h>

#include "Teams/LyraTeamSubsystem.h"

4c. Cpp: paint at every blocking hit, server-authoritative

Inside OnTargetDataReadyCallback (or wherever OnRangedWeaponTargetDataReady is invoked), gate on authority and call PaintZoneAtHit for each blocking hit:

if (HasAuthority(&CurrentActivationInfo))
{
    if (UTerraInkSubsystem* TerraInkSub = GetWorld()->GetSubsystem<UTerraInkSubsystem>())
    {
        // Resolve team -> layer once per shot. Falls back to the ability's authored
        // PaintLayer for solo/no-team avatars
        ETerraInkPaintLayer ResolvedLayer = PaintLayer;
        if (const ULyraTeamSubsystem* Teams = GetWorld()->GetSubsystem<ULyraTeamSubsystem>())
        {
            const int32 TeamId = Teams->FindTeamFromObject(GetAvatarActorFromActorInfo());
            const ETerraInkPaintLayer Mapped = TerraInk::GetPaintLayerForTeamIndex(TeamId);
            if (Mapped != ETerraInkPaintLayer::None)
            {
                ResolvedLayer = Mapped;
            }
        }

        for (int32 TargetIdx = 0; TargetIdx < LocalTargetDataHandle.Num(); ++TargetIdx)
        {
            if (const FGameplayAbilityTargetData_SingleTargetHit* HitData =
                static_cast<const FGameplayAbilityTargetData_SingleTargetHit*>(LocalTargetDataHandle.Get(TargetIdx)))
            {
                if (HitData->HitResult.bBlockingHit)
                {
                    TerraInkSub->PaintZoneAtHit(
                        HitData->HitResult,
                        PaintRadius,
                        ResolvedLayer,
                        PaintIntensity);
                }
            }
        }
    }
}

4d. Optional: per-shot style override

If you want different scatter/decals/VFX per weapon, pass a FGameplayTag as the 5th arg:

TerraInkSub->PaintZoneAtHit(HitData->HitResult, PaintRadius, ResolvedLayer, PaintIntensity, WeaponStyleTag);

WeaponStyleTag lives wherever the weapon stores it (PlayerState, weapon instance, ability spec). Empty tag = use the layer's DefaultStyleTag.

Add a few tags via Project Settings > Project > GameplayTags (or in Config/DefaultGameplayTags.ini):

+GameplayTagList=(Tag="Paint.Style.Default")
+GameplayTagList=(Tag="Paint.Style.Pistol")
+GameplayTagList=(Tag="Paint.Style.Rifle")
+GameplayTagList=(Tag="Paint.Style.Grenade")

Picking a Paint.Style.* namespace makes the meta = (Categories = "Paint.Style") filters on DefaultStyleTag and entry tags surface only relevant choices in the editor picker.

For a 2-team layout (Splatoon-style) you need two UTerraInkPaintConfig assets:

Each config carries a Styles map. One entry minimum (the Paint.Style.Default you set above) with at least one tier. Example tier:

Styles
  Paint.Style.Default
    Tiers
      [0]
        MinIntensity = 0.0
        Meshes.ScatterMeshes [optional]
        VFX.Systems          [optional]
        Decals.Materials     [optional]
        PCG.Graphs           [optional]
        bInstantOnHit = true (for one-shot hit scatter)

For per-weapon variation add Paint.Style.Pistol, Paint.Style.Rifle, etc. inside the same map. Both team configs share the same tag scheme; each has its own visuals.

7a. Recommended: drop ATerraInkWorldSetup in the level

ATerraInkWorldSetup is an optional convenience actor. It is not required, only the easiest entry point. Drop it into your gameplay map (or the persistent level for World Partition setups) and configure:

The actor's BeginPlay registers each config with the subsystem and calls InitializePaintSystem. No further setup required.

7b. Alternative: manual init from a game mode / experience component

If you do not want a placed actor, do the same handful of calls yourself – for example on your ALyraGameMode::InitGame or an experience-action component's activation:

UTerraInkSubsystem* TerraInkSub = World->GetSubsystem<UTerraInkSubsystem>();
TerraInkSub->SetArenaBounds(MyArenaBounds);
TerraInkSub->RegisterPaintLayerConfig(TeamAConfig);
TerraInkSub->RegisterPaintLayerConfig(TeamBConfig);
TerraInkSub->InitializePaintSystem();

This is the path to take when arena bounds are computed from streamed-in level data, or when the game mode wants to swap configs based on selected map / mode.

• Server authority on paint events. The authority gate in step 4c is required. ATerraInkReplicator (auto-spawned by the subsystem) handles the multicast.
• Late-joining clients. Existing paint state on the zone-map RTs replicates via the standard replication graph; the splat cell texture follows the same path. New clients see the current paint state when they join.
• Config swap mid-session. ATerraInkWorldSetup::SwitchToConfig(Tag) is server-only authority and multicasts to all clients. Used for phase changes (Day → BloodMoon, Calm → Storm).

• LyraEditor compiles clean: Engine/Build/BatchFiles/Build.bat LyraEditor Win64 Development -Project=<...>.uproject.
• Right-click DA_TeamA_PaintConfig > Validate Asset shows no errors.
• PIE single-player: equipped weapon paints the ground at impacts; tier scatter spawns once intensity exceeds tier 0.
• PIE 2-client: each client's avatar paints in its own team color (Team 0 → R, Team 1 → G). Both clients see both teams' paint.
• terraink.DumpStats console command prints non-zero ISM / scatter counts after a few shots.
• No log warnings from LogTerraInk matching *PaintZone called before InitializePaintSystem* (means the world setup actor never ran).

• Forgot authority gate.

  Symptom: double scatter, doubled paint intensity per shot. Fix: wrap the call in if (HasAuthority(&CurrentActivationInfo)) as shown in step 4c.

• PaintLayerConfigs empty on the world setup actor.

  Symptom: warnings on every paint hit "no config registered for layer N". Either wire the configs or accept the placeholder default config.

• Team subsystem lookup returns INDEX_NONE.

  Solo modes hit this; the fallback to authored PaintLayer keeps the weapon working. Verify your game mode actually assigns teams via ULyraTeamSubsystem::ChangeTeamForActor (or your own equivalent).

• DefaultStyleTag is unset on a config.

  Symptom: paint paints the RT but no scatter / VFX / decals spawn. Validator flags this as a Warning at edit time.

• Tags missing from the gameplay tag manager.

  Tag pickers show empty lists. Add the Paint.Style.* entries to DefaultGameplayTags.ini before authoring configs.