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Spawning static meshes server-side on EVRIMA

Short practical guide for spawning visible static meshes (decor, nests, gore, plants, skeletons) from UE4SS Lua on The Isle EVRIMA dedicated server.

The one thing you need to know

Don't try to use AStaticMeshActor + SetStaticMesh() from Lua. It looks like it should work, but the static mesh assignment is NOT a replicated UProperty in Unreal, the server has your cube, the client sees an invisible empty actor. The SetReplicates(true) flag doesn't help because there's no replication path for the mesh field.

DO this instead: spawn a Blueprint class that has the mesh baked into its class default. "Spawn class X" replicates fine because the client already knows what mesh class X uses by name.

This is what BodyDrop does for corpses, and what every working "spawn a thing" mod on EVRIMA does.

The basic spawn recipe

-- 1. Resolve the class by full object path
local classObj = StaticFindObject("/Game/TheIsle/.../BP_SomeThing.BP_SomeThing_C")
if classObj == nil then return false, "class not loaded" end

-- 2. Get a UWorld reference (any pawn or game-mode works)
local world = pawn:GetWorld()  -- or gameMode:GetWorld()
if world == nil then return false, "no world" end

-- 3. Spawn it
local loc = { X = 0, Y = 0, Z = 0 }
local rot = { Pitch = 0, Yaw = 0, Roll = 0 }
local okSpawn, actor = pcall(function() return world:SpawnActor(classObj, loc, rot) end)
if not okSpawn or actor == nil then return false, "spawn threw" end

-- 4. CRITICAL: validate the actor wrapper is not a nullptr
-- Terrain collision causes SpawnActor to return a non-nil Lua wrapper
-- around a NULLPTR UObject. Calling methods on that crashes the server.
local addr
pcall(function() addr = actor:GetAddress() end)
if addr == nil or addr == 0 then
    return false, "SpawnActor returned nullptr (terrain or invalid location)"
end

-- 5. Flip network flags so clients receive the actor.
-- SetReplicates + ForceNetUpdate are what a normal actor needs; it then
-- replicates on native distance relevancy. Do NOT reflexively add
-- bAlwaysRelevant (see Gotcha 3) — for a high-count/replicated spawn it is a
-- client load-in-crash amplifier, and it does nothing for ordinary decor.
pcall(function() actor:SetReplicates(true) end)
pcall(function() actor:ForceNetUpdate() end)

return true, actor

If SpawnActor fails (nullptr), resample a fresh XY near the target and re-derive ground (see Gotcha 2). Do not retry with an untraced vertical offset — an actor spawned into the void below the landscape reports success too.

Useful BP classes you can spawn

All paths verified to exist on the EVRIMA build. Get the full path by appending .BP_<Name>_C to the file path.

Nests

/Game/TheIsle/Core/Nests/BP_Nest_*, 11 variants:

  • BP_Nest_Mound_Large_H (large herbivore nest)
  • BP_Nest_Mound_Medium_H, BP_Nest_Mound_Small_H
  • BP_Nest_Burrow_* (burrow variants)
  • Plus carnivore variants

These have functional gameplay (eggs, breeding mechanics). Use cautiously.

Gore decor (/Game/TheIsle/Core/PickablePieces/)

Physics-enabled chunks for decoration or gore scenes:

  • BP_GoreEggCarnivoreSmall, BP_GoreEggCarnivoreMedium, BP_GoreEggCarnivoreLarge
  • BP_GoreEggHerbivoreSmall, BP_GoreEggHerbivoreMedium, BP_GoreEggHerbivoreLarge
  • BP_GoreHeart, BP_GoreIntestines
  • BP_GoreLungeLeft, BP_GoreLungeRight
  • BP_GoreMeat, BP_GoreMeatStretch, BP_GoreStomach

Edible by carnivores. Physics-active so they fall and rest.

Edible plants (/Game/TheIsle/Core/Spawnables/EdiblePlants/)

30+ variants, herbivore food + decor:

  • Common: BP_Agave_*, BP_Fiddlehead_*, BP_Fireweed_*, BP_Marigold_*, BP_Russula_*, BP_Sumac_*, BP_Trillium_*
  • Tropical trees (StaticSpawner pattern, these spawn a base + interactive pieces):
    • BP_BananaTreeStaticSpawner
    • BP_BrazilnutsTreeStaticSpawner
    • BP_CashewStaticSpawner
    • BP_CoconutTreeStaticSpawner
    • BP_JackfruitTreeStaticSpawner
    • BP_MangoTreeStaticSpawner
    • BP_PapayaTreeStaticSpawner
    • BP_PumpkinStaticSpawner
    • BP_HornedMelonStaticSpawner
    • BP_VariegatedOrangeStaticSpawner
  • Mushrooms: BP_ChanterelleMushroom_*, BP_JuvMushroom_*
  • Apollan trifoliums (lore plants): BP_AzureApollanK*, BP_CrimsonApollanK*, BP_VioletApollanK*
  • Roots: BP_RadishRoot_*, BP_WildPotatoRoot_*, BP_SunchokeRoot_*

Dino corpse decor

Spawning a dino BP and immediately killing/ragdolling it produces a usable corpse mesh (see BodyDrop pattern for the full recipe). Cheaper than running live AI. The species set BodyDrop ships with:

/Game/TheIsle/Core/Characters/Dinosaurs/<Species>/BP_<Species>.BP_<Species>_C

Species: allosaurus, beipiaosaurus, carnotaurus, ceratosaurus, compsognathus, deinosuchus, diabloceratops, dilophosaurus, dryosaurus, gallimimus, herrerasaurus, hypsilophodon, maiasaura, omniraptor, pachycephalosaurus, pteranodon, stegosaurus, tenontosaurus, triceratops, troodon, tyrannosaurus.

Skeleton meshes (untested but probable)

Every dino has a SK_<Species>_Bones skeletal mesh asset at /Game/TheIsle/Characters/Dinosaurs/<Species>/Mesh/. These are the skeleton-only mesh assets used by death/decay states.

You can't spawn them directly as an actor (they're meshes, not BPs), you'd need a custom BP wrapper that uses one of these meshes as its baked class default. Building that BP requires Unreal Editor and a .pak asset pack.

Burrow construction kit (/Game/TheIsle/BurrowConcept/)

Unreleased prototype set, could be assembled into a custom underground sandbox:

  • BP_BurrowActor (container)
  • BP_BurrowEntrance (surface entry)
  • BP_BurrowConnectorCorridor (hallway)
  • BP_BurrowConnectorNoExit (dead end)
  • BP_BurrowConnectorRoomAllSides (4-way junction)
  • BP_GeneratedVoxelMeshActor + BPI_VoxelInterface (procedural voxel terrain)
  • BP_InternalInteractor (in-burrow interactables)

Misc

  • BP_NameWidgetActor, floating name tags
  • BP_AmbZone, ambient sound zone
  • BP_SpawnBounds, defines spawn zones
  • BP_AdminPawn, admin spectator pawn
  • BP_FishSchool_*, fish school spawners (6 variants)

Gotchas

  1. Always validate actor:GetAddress() ~= 0 after SpawnActor. Terrain collision returns a non-nil Lua wrapper around a nullptr UObject, and calling methods on it crashes the server with a 30-second-delayed AV that pcall cannot catch.

  2. Find real ground; don't spawn at a blind vertical offset. EVRIMA's heightmap is uneven, and spawning at a naive ground Z can clip the actor into a hill — but the fix is a downward trace to the true surface at your XY, not a fixed +1500. A blind offset is the trap the corpse-spawner (BodyDrop) had to remove: SpawnActor succeeds in the empty void below the landscape, so an untraced offset over the wrong spot buries the actor under the map. Trace from a high ceiling Z straight down, take the hit, spawn just above it. Note the old "+1500 and let it fall" advice only ever did anything for a physics/ragdoll actor (a corpse); a static decor mesh spawned at +1500 just floats at +1500.

  3. Network flags for client visibility:

    actor:SetReplicates(true)
actor:ForceNetUpdate()

    These two are what an actor needs; it then replicates on native distance relevancy like anything else. bAlwaysRelevant = true is optional and usually wrong here: it forces the actor into every joining client's initial replication burst, which at scale (many spawned actors, e.g. corpses) is a documented client load-in crash — BodyDrop v004 removed it for exactly that reason. Reach for it only for a single, must-always-see actor, never as a blanket "make it visible" flag.

  4. DO NOT call K2_DestroyActor to clean up server-side. If gameplay destroyed the actor independently (corpse-eaten, decay timer, etc.), your destroy call fires a native AV on freed memory. Even checking GetAddress() ~= 0 first isn't safe, freed-but-not-yet-reused memory passes the check and the destroy itself crashes. For cleanup, restart the server. For tracking, use a write-once table you read for stats but never use to destroy from.

  5. Don't call FindFirstOf("BP_Class_Name") on a class with no live instances. That call can crash UE4SS internally. Use StaticFindObject("/Game/full/path.BP_Name_C") instead, that always works as long as the class is loaded into UObject space.

  6. Custom meshes need a .pak, not Lua. If you want to add a NEW mesh that isn't in the game already, you have to build a custom BP in Unreal Editor wrapping that mesh, package it as a .pak file, and drop it in the server's Paks/ directory. Server-side Lua can only spawn classes that already exist in the game build.

What about VFX / particle effects?

Mostly doesn't work server-side from Lua. The dedicated server has no renderer, so UNiagaraFunctionLibrary:SpawnSystemAtLocation returns nullptr.

BP-wrapped effect actors (like BP_SmiteEffect, BP_BloodSplat, BP_Footprint) DO spawn via world:SpawnActor, but their effect playback is gated by client-side execution paths the server can't trigger. Result: invisible empty actors.

The ONE exception is BP_HallucinationFog, it's wired into the venom/dilo hallucination gameplay state machine, so its replication path is fully built. You can spawn that and clients will see the fog. Other 7+ effect actors spawn-but-don't-render.

For real visual effects mods, you need a .pak-based asset pack with custom Niagara systems baked in.