Rook

Based on game build 714014 | Last updated: 2026-03-07

Overview

The rook is a boss-level hostile entity implemented as a prefab using the Entity Component System (ECS). It is designed for the Chess set in DST and features aggressive movement (including platform hopping), collision-based ground destruction, sleeping/waking behavior, and two variants: standard and nightmare mode. The prefab uses clockwork_common utilities for shared logic (e.g., retargeting, sleep/wake tests), integrates with the combat, health, locomotor, sleeper, and lootdropper components, and supports both client- and server-side behaviors (e.g., ground FX).

Usage example

-- Standard Rook prefab
local rook = Prefab("rook", ...) -- instantiation handled by engine via return values in source file

-- nightmare variant
local nightmare_rook = Prefab("rook_nightmare", ...)

-- The `SpawnGroundFx()` method is exposed publicly on the instance:
-- rook_instance.SpawnGroundFx()

Dependencies & tags

Components used: combat, follower, health, inspectable, knownlocations, lootdropper, locomotor, embarker, drownable, sleeper, acidinfusible (nightmare only).
Tags added: monster, hostile, chess, rook, largecreature (normal only), cavedweller (nightmare only), shadow_aligned (nightmare only).
Tags checked: None directly via HasTag, but IsAsleep() and state graph tags (running, running_collides) are used in logic.

Properties

Property	Type	Default Value	Description
groundfx	net_event	nil (assigned at runtime)	Network event used to trigger ground FX on clients.
recentlycharged	table	{} (empty table)	Tracks entities recently collided with to avoid repeated collisions within 3 seconds.
override_combat_fx_size	string	"med"	Controls size of combat hit FX.
kind	string	""	Unused (commented as unused?); likely legacy.
soundpath	string	""	Sound base path (set per variant).
effortsound	string	""	Effort sound path (set per variant).

Main functions

SpawnGroundFx(inst)

• Description: Triggers client-side ground FX for the rook. Pushes a networked event and spawns a one-time FX entity only on non-dedicated clients.
• Parameters: inst (Entity instance) — the rook instance calling the function.
• Returns: Nothing.
• Error states: No FX is spawned on dedicated servers (TheNet:IsDedicated() returns true).

InitGroundFx_Client(inst)

• Description: Registers the listener for the rook.groundfx event on the client to trigger OnGroundFx_Client.
• Parameters: inst (Entity instance) — the rook instance.
• Returns: Nothing.

OnGroundFx_Client(inst)

• Description: Client-side FX spawner. Constructs and positions a collapse_small-style FX entity at the rook's location and plays a sound.
• Parameters: inst (Entity instance) — the rook instance.
• Returns: Nothing.

DoCollideShake(inst)

• Description: Triggers a camera shake effect for all clients when the rook collides at high speed.
• Parameters: inst (Entity instance).
• Returns: Nothing.

oncollide(inst, other)

• Description: Collision callback. Detects high-speed collisions with destructible workables, triggers shake, schedules onothercollide, and caches collision time to prevent spam.
• Parameters:
  inst (Entity) — the rook.
  other (Entity) — the collided object.
• Returns: Nothing.
• Error states: Early exits if state graph is not running_collides, target is invalid/player, or collision speed < sqrt(42).

onothercollide(inst, other)

• Description: Handles actual destruction of destructible objects (workable with valid action ≠ NET) upon collision; otherwise clears the collision cache.
• Parameters:
  inst (Entity) — the rook.
  other (Entity) — the collided workable.
• Returns: Nothing.

Retarget(inst)

• Description: Helper used by combat:SetRetargetFunction. Delegates to clockwork_common.Retarget with TUNING.ROOK_TARGET_DIST.
• Parameters: inst (Entity) — the rook instance.
• Returns: Boolean — whether a new target should be selected.

KeepTarget(inst, target)

• Description: Helper used by combat:SetKeepTargetFunction. Allows target retention while running or per clockwork_common.KeepTarget.
• Parameters:
  inst (Entity) — the rook.
  target (Entity) — the current target.
• Returns: Boolean — whether to retain the target.

MakeRook(...)

• Description: Core prefab factory function. Returns a Prefab closure that instantiates the entity and attaches all required components, sets state graph/brain, and runs variant-specific post-init logic.
• Parameters:
  name (string) — prefab name (e.g., "rook", "rook_nightmare").
  common_postinit (function?) — per-variant initialization (e.g., build setup, tags).
  master_postinit (function?) — server-only initialization (e.g., loot tables, regen).
  _assets, _prefabs — arrays for asset and sub-prefab dependencies.
• Returns: Prefab — the resulting prefab factory.

MakeRook nested factory fn()

• Description: Inner instantiation function called by the Prefab system. Sets up transform, physics, components, tags, state graph, brain, and listeners.
• Parameters: None (called internally by Prefab).
• Returns: Entity — fully constructed and initialized rook instance.

normal_common_postinit(inst), normal_master_postinit(inst)

• Description: Standard rook post-initialization logic. Sets build, tag largecreature, loot table, and health regen.
• Parameters: inst (Entity) — the rook instance.
• Returns: Nothing.

nightmare_common_postinit(inst), nightmare_master_postinit(inst)

• Description: Nightmare rook post-initialization. Adds cavedweller/shadow tags, sets acid infusibility, updates sound paths, and sets nightmare loot table.
• Parameters: inst (Entity) — the rook instance.
• Returns: Nothing.

onruinsrespawn(inst, respawner)

• Description: Callback for RuinsRespawner. Forces the rook into the "ruinsrespawn" state if the respawner is awake.
• Parameters:
  inst (Entity) — the rook instance.
  respawner (Entity) — the ruins respawner triggering the callback.
• Returns: Nothing.

Events & listeners

• Listens to:
  attacked — triggers clockwork_common.OnAttacked for status effects.
  newcombattarget — triggers clockwork_common.OnNewCombatTarget for AI updates.
  rook.groundfx (client only) — triggers OnGroundFx_Client for visual FX.
  animover — on FX entity, triggers inst.Remove.
• Pushes:
  rook.groundfx (client-side net event) — triggers FX rendering.
  (Events are pushed by other components or via PushEvent in clockwork_common, not directly in rook code.)