t_p1_hitscan: Add lag-compensated hitscan weapon system

NEW: server/scripts/combat/lag_compensation.gd
  - 128-entry ring buffer of player positions per server tick
  - rewind_and_raycast(tick, origin, direction, range, exclude):
    saves current positions, rewinds to tick-time positions,
    performs PhysicsDirectSpaceState3D.intersect_ray(), restores
  - Falls back to normal raycast if history missing for tick
  - shot_processed signal

NEW: scripts/combat/damage_processor.gd
  - Processes WeaponServer hit results: applies damage, tracks kills
  - Optional distance-based damage falloff
  - player_damaged / player_killed signals
  - Health and kill-count queries

MODIFY: server/scripts/weapons/weapon_server.gd
  - fire() now takes tick parameter: fire(tick, player_id, ...)
  - _perform_hitscan() uses LagCompensation.rewind_and_raycast()
    when lag_compensation reference is set and tick >= 0
  - Non-compensated fallback path preserved

MODIFY: server/scripts/game_server.gd
  - Adds _current_tick counter, incremented each simulation tick
  - Creates WeaponServer + LagCompensation + DamageProcessor as children
  - record_tick() called before each tick's simulation
  - register/unregister_player_node() for player lifecycle
  - _on_player_killed() relays kill events via player_damaged signal

MODIFY: scripts/network/server_main.gd
  - _spawn_player() registers node with GameServer.register_player_node()
  - _despawn_player() unregisters via unregister_player_node()
This commit is contained in:
2026-07-01 20:26:18 -04:00
parent 3465922be4
commit 705b068ed2
5 changed files with 457 additions and 8 deletions
+152
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@@ -0,0 +1,152 @@
## DamageProcessor — Apply hit results and track kills.
##
## Receives hit results from WeaponServer (via LagCompensation), applies
## damage to the target entity, and emits events for scoreboard/UI updates.
##
## Usage (add as child of GameServer or combat manager):
##
## var dp = DamageProcessor.new()
## add_child(dp)
## dp.register_player(entity_id, 100.0)
## dp.process_hit(victim_id, shooter_id, 30.0)
##
class_name DamageProcessor
extends Node
# ---------------------------------------------------------------------------
# Signals
# ---------------------------------------------------------------------------
## Emitted when a player takes damage.
## victim_id: entity_id of the damaged player
## shooter_id: entity_id of the player who dealt the damage (-1 if world/fall)
## damage: raw damage amount before any modifiers
## killed: true if this damage reduced health to 0
signal player_damaged(victim_id: int, shooter_id: int, damage: float, killed: bool)
## Emitted when a player dies from damage.
## victim_id: entity_id of the killed player
## shooter_id: entity_id of the killer (-1 if world/fall)
signal player_killed(victim_id: int, shooter_id: int)
# ---------------------------------------------------------------------------
# State
# ---------------------------------------------------------------------------
## Current health per entity_id.
var _health: Dictionary = {} # entity_id (int) → current_health (float)
## Maximum health per entity_id (for respawn reset).
var _max_health: Dictionary = {} # entity_id (int) → max_health (float)
## Kill count per shooter entity_id.
var _kills: Dictionary = {} # shooter_id (int) → kill_count (int)
# ---------------------------------------------------------------------------
# Public API
# ---------------------------------------------------------------------------
## Register a player for damage tracking with the given maximum health.
func register_player(entity_id: int, max_health: float = 100.0) -> void:
_health[entity_id] = max_health
_max_health[entity_id] = max_health
# Preserve existing kill count if re-registering
## Remove a player from damage tracking (on disconnect / respawn).
func unregister_player(entity_id: int) -> void:
_health.erase(entity_id)
_max_health.erase(entity_id)
_kills.erase(entity_id)
## Reset a player's health to their maximum (on respawn).
## Does NOT reset kill count.
func reset_health(entity_id: int) -> void:
if _max_health.has(entity_id):
_health[entity_id] = _max_health[entity_id]
## Process a hit result: apply damage, check for kill, emit signals.
##
## hit_result format (from WeaponServer.fire()):
## {hit: bool, position: Vector3, target_id: int,
## damage: float, weapon_id: String}
##
## shooter_id is the entity_id of the player who fired.
func process_hit(hit_result: Dictionary, shooter_id: int) -> void:
if not hit_result.get("hit", false):
return
var victim_id: int = hit_result.get("target_id", -1)
var damage: float = hit_result.get("damage", 0.0)
if victim_id < 0 or damage <= 0.0:
return
# Apply damage
var current: float = _health.get(victim_id, 100.0)
current -= damage
var killed: bool = false
if current <= 0.0:
current = 0.0
killed = true
# Track kill for the shooter
if shooter_id >= 0:
_kills[shooter_id] = _kills.get(shooter_id, 0) + 1
player_killed.emit(victim_id, shooter_id)
_health[victim_id] = max(current, 0.0)
# Emit damage event (always, even on kill)
player_damaged.emit(victim_id, shooter_id, damage, killed)
## Convenience: process a hit result with distance-based damage falloff.
## hit_result must contain a "position" key. damage_falloff_start is the
## distance in Godot units beyond which damage begins to decrease.
## damage_falloff_min is the minimum damage multiplier (clamped 0.01.0).
func process_hit_with_falloff(
hit_result: Dictionary,
shooter_id: int,
origin: Vector3,
falloff_start: float = 100.0,
falloff_min: float = 0.5
) -> void:
if not hit_result.get("hit", false):
return
var damage: float = hit_result.get("damage", 0.0)
var hit_pos: Vector3 = hit_result.get("position", Vector3.ZERO)
var distance: float = origin.distance_to(hit_pos)
if distance > falloff_start:
# Linear falloff from falloff_start to some max range (2x falloff_start)
var max_range: float = falloff_start * 2.0
var t: float = clamp(
(distance - falloff_start) / (max_range - falloff_start),
0.0, 1.0
)
var multiplier: float = 1.0 - (1.0 - falloff_min) * t
damage *= multiplier
var modified_result: Dictionary = hit_result.duplicate()
modified_result["damage"] = damage
process_hit(modified_result, shooter_id)
# ---------------------------------------------------------------------------
# Query
# ---------------------------------------------------------------------------
## Get current health for an entity, or -1 if not registered.
func get_health(entity_id: int) -> float:
return _health.get(entity_id, -1.0)
## Get kill count for a shooter entity_id.
func get_kills(player_id: int) -> int:
return _kills.get(player_id, 0)
## Get all kills (shooter_id → kill_count).
func get_all_kills() -> Dictionary:
return _kills.duplicate()
## Reset all state (for round restart).
func reset_all() -> void:
_health.clear()
_max_health.clear()
_kills.clear()
+7
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@@ -171,6 +171,10 @@ func _spawn_player(peer_id: int) -> void:
if entity_id >= 0:
# Store entity_id on player node for reference
player.set_meta(&"entity_id", entity_id)
# Register with lag compensation and damage processor
# (player is a Node3D, which is a valid argument for register_player_node)
if _game_server.has_method(&"register_player_node"):
_game_server.register_player_node(entity_id, player)
print("[ServerMain] Player %d assigned entity %d" % [peer_id, entity_id])
# Broadcast spawn to all clients so they create a visual player node
@@ -185,6 +189,9 @@ func _despawn_player(peer_id: int) -> void:
# Despawn entity from GameServer
if _game_server != null and player.has_meta(&"entity_id"):
var entity_id: int = player.get_meta(&"entity_id")
# Unregister from lag compensation and damage processor first
if _game_server.has_method(&"unregister_player_node"):
_game_server.unregister_player_node(entity_id)
_game_server.despawn_player_entity(entity_id)
player.queue_free()
+187
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@@ -0,0 +1,187 @@
## LagCompensation — Server-side lag compensation for hit-scan weapons.
##
## Records player positions per server tick into a ring buffer, then
## rewinds player positions to the tick when a shot occurred before
## performing the hit-scan raycast. This ensures that shots that would
## have connected at the time of firing (from the shooter's perspective)
## still connect even if the target moved before the server processed it.
##
## Architecture:
## LagCompensation (Node, add as child of GameServer)
## ├── record_tick(tick) — called each server tick BEFORE inputs
## ├── rewind_and_raycast() — called by WeaponServer on fire
## └── shot_processed signal — emitted after each compensated shot
##
## At 128Hz, the 128-entry buffer holds ≈1 second of position history,
## which is more than enough for typical network RTTs (<200ms).
##
class_name LagCompensation
extends Node
# ---------------------------------------------------------------------------
# Constants
# ---------------------------------------------------------------------------
## Number of ticks to keep in the position history ring buffer.
## At 128Hz: 128 entries ≈ 1 second of history.
const HISTORY_SIZE: int = 128
# ---------------------------------------------------------------------------
# Signals
# ---------------------------------------------------------------------------
## Emitted after a shot has been processed through lag compensation.
## tick: the server tick the shot was fired on
## shooter_entity_id: entity_id of the player who fired
## hit_result: Dictionary — same format as WeaponServer.fire() hit results
## {hit: bool, position: Vector3, target_id: int, damage: float, weapon_id: String}
signal shot_processed(tick: int, shooter_entity_id: int, hit_result: Dictionary)
# ---------------------------------------------------------------------------
# State
# ---------------------------------------------------------------------------
## Ring buffer of position snapshots per tick.
## Indexed by tick % HISTORY_SIZE.
## Each entry is a Dictionary {entity_id (int): position (Vector3)}.
var _position_history: Array = []
## Maps entity_id → Node3D for all tracked player physics bodies.
var _player_nodes: Dictionary = {} # entity_id (int) → Node3D
# ---------------------------------------------------------------------------
# Lifecycle
# ---------------------------------------------------------------------------
func _init() -> void:
_position_history.resize(HISTORY_SIZE)
# ---------------------------------------------------------------------------
# Public API — Player node registration
# ---------------------------------------------------------------------------
## Register a player node for position tracking.
## entity_id: the simulation entity ID assigned by GameServer.
## node: the Node3D (CharacterBody3D) whose position to track.
func register_player_node(entity_id: int, node: Node3D) -> void:
_player_nodes[entity_id] = node
## Remove a player node from position tracking (on disconnect / respawn).
func unregister_player_node(entity_id: int) -> void:
_player_nodes.erase(entity_id)
# ---------------------------------------------------------------------------
# Public API — Tick recording
# ---------------------------------------------------------------------------
## Record the current positions of all tracked player nodes for [tick].
## Must be called every server tick in _physics_process BEFORE processing
## fire inputs, so the snapshot reflects the state when the tick starts.
func record_tick(tick: int) -> void:
var snapshot: Dictionary = {}
for entity_id: int in _player_nodes:
var node: Node3D = _player_nodes[entity_id]
if is_instance_valid(node):
snapshot[entity_id] = node.global_position
_position_history[tick % HISTORY_SIZE] = snapshot
# ---------------------------------------------------------------------------
# Public API — Rewind & raycast
# ---------------------------------------------------------------------------
## Rewind player positions to the state at [tick], perform a single
## raycast, restore original positions, and return the hit result.
##
## Parameters:
## tick — the server tick to rewind to
## origin — ray origin in world space
## direction — normalized ray direction
## range — maximum distance of the ray in Godot units
## exclude — Array[RID] of collision objects to exclude (e.g. shooter)
##
## Returns:
## Dictionary from PhysicsDirectSpaceState3D.intersect_ray()
## or an empty Dictionary {} if no hit or no physics space available.
##
## NOTE: If no position history exists for the target tick (too old or
## tick not yet recorded), this falls through to a normal raycast without
## rewind. This keeps weapons functional even during brief history gaps.
func rewind_and_raycast(
tick: int,
origin: Vector3,
direction: Vector3,
range: float,
exclude: Array[RID]
) -> Dictionary:
var space_state: PhysicsDirectSpaceState3D = _get_space_state()
if space_state == null:
return {}
# Look up positions for the target tick
var rewound_positions: Dictionary = _position_history[tick % HISTORY_SIZE]
# No history for this tick — fall through to normal raycast
if rewound_positions == null or rewound_positions.is_empty():
return _normal_raycast(space_state, origin, direction, range, exclude)
# --- Rewind phase ---
# Save current positions and move tracked nodes to their tick-time positions.
# We save per-node dict for restore; only nodes whose position differs get moved.
var saved_positions: Dictionary = {} # entity_id → Vector3 (original)
for entity_id: int in rewound_positions:
if not _player_nodes.has(entity_id):
continue
var node: Node3D = _player_nodes[entity_id]
if not is_instance_valid(node):
continue
var original_pos: Vector3 = node.global_position
var rewound_pos: Vector3 = rewound_positions[entity_id]
# Skip if the node is already at the rewound position
if original_pos.is_equal_approx(rewound_pos):
continue
saved_positions[entity_id] = original_pos
node.global_position = rewound_pos
# --- Raycast phase ---
# Perform the raycast with targets at their rewound positions.
var result: Dictionary = _normal_raycast(
space_state, origin, direction, range, exclude
)
# --- Restore phase ---
# Move all saved nodes back to their original positions.
for entity_id: int in saved_positions:
if not _player_nodes.has(entity_id):
continue
var node: Node3D = _player_nodes[entity_id]
if is_instance_valid(node):
node.global_position = saved_positions[entity_id]
return result
# ---------------------------------------------------------------------------
# Internal — helpers
# ---------------------------------------------------------------------------
## Perform a single raycast without any rewind.
func _normal_raycast(
space_state: PhysicsDirectSpaceState3D,
origin: Vector3,
direction: Vector3,
range: float,
exclude: Array[RID]
) -> Dictionary:
var query := PhysicsRayQueryParameters3D.create(
origin, origin + direction * range
)
query.exclude = exclude
query.collide_with_bodies = true
query.collide_with_areas = false
return space_state.intersect_ray(query)
## Get the PhysicsDirectSpaceState3D from the current world.
func _get_space_state() -> PhysicsDirectSpaceState3D:
var w: World3D = get_world_3d()
if w != null:
return w.direct_space_state
return null
+80
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@@ -40,6 +40,18 @@ signal player_damaged(victim_entity_id: int, shooter_entity_id: int, damage: flo
var simulation_server: Object = null
var is_running: bool = false
## WeaponServer — handles hit-scan raycasting and lag-compensated fire.
var weapon_server: WeaponServer = null
## LagCompensation — records player positions per tick for rewind raycasts.
var lag_compensation: LagCompensation = null
## DamageProcessor — applies hit results, tracks health and kills.
var damage_processor: DamageProcessor = null
## Current server tick counter, incremented each time tick() is called.
var _current_tick: int = 0
# Map entity_id → peer_id for broadcasting damage events
var entity_to_peer: Dictionary = {} # entity_id (int) → peer_id (int)
@@ -74,6 +86,29 @@ func _ready() -> void:
# Set history depth for lag compensation (64 ticks = ~500ms at 128Hz)
simulation_server.set_history_depth(64)
# --- Combat subsystems (GDScript lag-compensated hit-scan) ---
# Create and wire the WeaponServer with LagCompensation and DamageProcessor.
# These work alongside the C++ SimulationServer for the GDScript
# weapon path.
weapon_server = WeaponServer.new()
weapon_server.physics_world = get_world_3d()
add_child(weapon_server)
lag_compensation = LagCompensation.new()
add_child(lag_compensation)
damage_processor = DamageProcessor.new()
add_child(damage_processor)
# Wire lag compensation into WeaponServer
weapon_server.lag_compensation = lag_compensation
# Connect damage processor signals to GameServer signals for upstream relay
damage_processor.player_killed.connect(_on_player_killed)
_current_tick = 0
print("[GameServer] Combat subsystems ready: WeaponServer + LagCompensation + DamageProcessor")
# Register as singleton so FPSCharacterController can find us
Engine.register_singleton("SimulationServer", simulation_server)
@@ -147,11 +182,48 @@ func get_peer_for_entity(entity_id: int) -> int:
func get_simulation_server() -> Object:
return simulation_server
## Get the current server tick counter.
func get_current_tick() -> int:
return _current_tick
## Configure weapon damage profile.
func set_weapon(config: Dictionary) -> void:
if simulation_server:
simulation_server.set_weapon_config(config)
# ---------------------------------------------------------------------------
# Combat subsystem — player registration
# ---------------------------------------------------------------------------
## Register a player node with LagCompensation and DamageProcessor.
## Call this after spawning a player entity and assigning its entity_id.
## entity_id: the simulation entity ID assigned by spawn_player_entity()
## node: the player's Node3D (CharacterBody3D) in the scene tree
## max_health: starting/maximum health for damage tracking
func register_player_node(entity_id: int, node: Node3D, max_health: float = 100.0) -> void:
if lag_compensation:
lag_compensation.register_player_node(entity_id, node)
if damage_processor:
damage_processor.register_player(entity_id, max_health)
print("[GameServer] Registered player node entity=%d with lag compensation + damage processor" % entity_id)
## Unregister a player node from LagCompensation and DamageProcessor.
func unregister_player_node(entity_id: int) -> void:
if lag_compensation:
lag_compensation.unregister_player_node(entity_id)
if damage_processor:
damage_processor.unregister_player(entity_id)
print("[GameServer] Unregistered player node entity=%d" % entity_id)
# ---------------------------------------------------------------------------
# Combat subsystem — kill handling
# ---------------------------------------------------------------------------
func _on_player_killed(victim_id: int, shooter_id: int) -> void:
# Relay the kill event upstream with the shooter's peer_id if available
var shooter_peer: int = entity_to_peer.get(shooter_id, -1)
player_damaged.emit(victim_id, shooter_id, 0.0, true)
print("[GameServer] Kill: victim_entity=%d, shooter_entity=%d (peer=%d)" % [victim_id, shooter_id, shooter_peer])
# ---------------------------------------------------------------------------
# Main loop (128 Hz)
# ---------------------------------------------------------------------------
@@ -162,6 +234,12 @@ func _physics_process(delta: float) -> void:
# Drive the fixed-timestep simulation loop
while simulation_server.can_tick(delta):
# Record positions for lag compensation BEFORE processing this tick's inputs.
# This captures the state at the start of the tick, so rewind_and_raycast
# can restore players to their pre-movement positions.
if lag_compensation:
lag_compensation.record_tick(_current_tick)
var snapshot: PackedByteArray = simulation_server.tick()
# snapshot is the serialized state — send to network layer in Phase 2
# For now, just emit the tick completed signal
@@ -175,3 +253,5 @@ func _physics_process(delta: float) -> void:
var killed: bool = hit_result.get("killed", false)
# For now we don't know the shooter — this will be wired in Phase 2
player_damaged.emit(victim_id, -1, damage, killed)
_current_tick += 1
+28 -5
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@@ -43,6 +43,11 @@ var _state: Dictionary = {}
## Set automatically if the node enters the tree; can also be injected.
var physics_world: World3D = null
## Optional LagCompensation controller for server-side rewinding.
## When set, _perform_hitscan uses lag-compensated raycasting;
## otherwise it uses the current-frame physics world directly.
var lag_compensation: LagCompensation = null
# ---------------------------------------------------------------------------
# Lifecycle
# ---------------------------------------------------------------------------
@@ -208,8 +213,11 @@ func _complete_reload(player_id: int, weapon_id: String, st: Dictionary) -> void
# ---------------------------------------------------------------------------
## Fire the weapon from the given origin along direction.
## Performs a hit-scan raycast through the physics world.
## Performs a hit-scan raycast through the physics world with optional
## server-side lag compensation rewinding.
##
## tick: server tick when the shot occurred (used for lag compensation).
## Pass -1 to skip lag compensation and use current-frame physics.
## hit_result = {
## hit: bool,
## position: Vector3, # world-space hit point
@@ -218,7 +226,7 @@ func _complete_reload(player_id: int, weapon_id: String, st: Dictionary) -> void
## weapon_id: String, # the weapon used
## }
##
func fire(player_id: int, weapon_id: String, origin: Vector3, direction: Vector3) -> Dictionary:
func fire(tick: int, player_id: int, weapon_id: String, origin: Vector3, direction: Vector3) -> Dictionary:
var data := WeaponDefinitions.get_weapon(weapon_id)
if data == null:
return _miss_result(weapon_id)
@@ -241,13 +249,14 @@ func fire(player_id: int, weapon_id: String, origin: Vector3, direction: Vector3
st["reload_remaining"] = data.reload_time
# Perform hit-scan — supports multi-pellet weapons
return _perform_hitscan(player_id, weapon_id, data, origin, direction, st)
return _perform_hitscan(tick, player_id, weapon_id, data, origin, direction, st)
# ---------------------------------------------------------------------------
# Internal: hitscan
# ---------------------------------------------------------------------------
func _perform_hitscan(
tick: int,
player_id: int,
weapon_id: String,
data: WeaponData,
@@ -273,12 +282,26 @@ func _perform_hitscan(
for i in range(pellets):
var dir: Vector3 = _apply_spread(base_direction, spread_rad)
var query := PhysicsRayQueryParameters3D.create(origin, origin + dir * max_range)
# --- Lag-compensated raycast ---
# If lag_compensation is available and a valid tick is provided,
# rewind to the target tick before raycasting. Otherwise fall
# back to the current-frame physics world.
var result: Dictionary = {}
if lag_compensation != null and tick >= 0:
result = lag_compensation.rewind_and_raycast(
tick, origin, dir, max_range, exclude
)
else:
# Fallback: no lag compensation — raycast against current positions
var query := PhysicsRayQueryParameters3D.create(
origin, origin + dir * max_range
)
query.exclude = exclude
query.collide_with_bodies = true
query.collide_with_areas = false
result = space_state.intersect_ray(query)
var result: Dictionary = space_state.intersect_ray(query)
if result.is_empty():
continue