godot-game-loop-waves

name	godot-game-loop-waves
description	Expert patterns for managing combat waves, difficulty scaling, and automated enemy spawning in Godot 4. Use when building wave-based shooters, tower defense, or arena games.

Architectural Thinking: The "Wave-State" Pattern

A Master implementation treats waves as Data-Driven Transitions. Instead of hardcoding spawn counts, use a WaveResource to define "Encounters" that the WaveManager processes sequentially.

Core Responsibilities

• Manager: Orchestrates the timeline. Handles delays between waves and tracks "Victory" conditions (all enemies dead).
• Spawner: Decoupled nodes that provide spatial context for where enemies appear (wave_spawner.gd / wave_weighted_spawner.gd).
• Resource: Immutable data containers that allow designers to rebalance the game without touching code.

Density Decision Tree (pick scale before coding)

Live density	Approach	MANDATORY loads
Under ~80 SceneTree enemies	Node manager + Marker spawners	wave_manager.gd, wave_spawner.gd, wave_resource.gd
Swarm visuals / hundreds	MultiMesh + weighted composition	wave_loop_patterns.gd (MultiMesh / async path), wave_weighted_spawner.gd
~10k bodies	PhysicsServer / NavigationServer RIDs (no per-mob Node)	wave_loop_patterns.gd server-RID patterns; do not scale wave_manager node spawns

wave_manager.gd is the SceneTree golden path (deferred add_child, group/signal clear counts, optional pool). Treat it as prototype→mid-scale — for RID swarms, follow wave_loop_patterns.gd instead of instantiating thousands of nodes.

Composition Golden Path

1. Author a wave_resource.gd composition table.
2. Place wave_spawner.gd Markers (or wave_weighted_spawner.gd when variety weights matter).
3. Point wave_manager.gd spawner at that Marker; manager defers spawn and clears via &"enemies" group + signals.
4. When weights replace fixed counts, call WaveWeightedSpawner.spawn_enemy() from the composition loop (or set manager spawner to the weighted node).

Expert Code Patterns

1. The Async Wave Trigger

Use await timers in wave_manager.gd — MANDATORY read before writing a custom timeline. Spawns use call_deferred(&"add_child", …); clear via signals/groups (not get_children() scans).

2. Composition-Based Spawning

Define variety in wave_resource.gd; place units with wave_spawner.gd / wave_weighted_spawner.gd. Do not hardcode scene paths in the manager.

Master Decision Matrix: Progression

Pattern	Best For	Logic
Linear	Story missions	Hand-crafted list of WaveResource.
Endless	Survival modes	Code-generated WaveResource with multiplier math.
Triggered	RPG Encounters	Wave starts only when player enters an Area3D.

NEVER Do

• NEVER iterate through get_children() to find all enemies — This is extremely slow. Always add enemies to an "enemies" group and use get_tree().get_nodes_in_group(&"enemies") for efficient access.
• NEVER constantly instantiate() and queue_free() hundreds of enemies — This causes garbage collection stutters. Use an object pool to reuse existing enemy instances.
• NEVER spawn thousands of separate MeshInstance3D nodes for swarms — This will tank your draw calls. Use MultiMeshInstance3D to batch thousands of meshes into a single GPU call.
• NEVER calculate pathfinding for hundreds of agents on the main thread — This will freeze your game. Enable use_async_iterations on your navigation regions or use NavigationServer3D.query_path().
• NEVER forget to check is_inside_tree() before adding a child — If the spawner is queued for deletion, adding a child will crash. Always verify the spawner is still active in the tree.
• NEVER assign a preloaded resource (like stats.tres) directly to spawned mobs — They will all share the exact same health/stats. Always call base_stats.duplicate_deep() to give each mob its own unique data.
• NEVER use standard strings for high-frequency group calls — Always use StringName (&"enemies", &"take_damage") for optimal hash performance and to avoid unnecessary string allocations.
• NEVER spawn entities directly inside physics callbacks synchronously — Instantiating nodes during physics steps can corrupt the physics state. Always use call_deferred(&"add_child", enemy).
• NEVER leave CollisionShapes on dead enemies active — Corpses will block towers and navigation. Use set_deferred("disabled", true) immediately upon death.
• NEVER synchronize complex Object types via MultiplayerSynchronizer — It only supports primitive types. For complex data, sync a UID or ID and look up the data locally on the client.
• NEVER auto-start waves without player feedback — Always provide a UI countdown, a visual "Wave Incoming" effect, or a start button to maintain player agency.
• NEVER hardcode spawn positions at (0,0,0) — Use Marker3D nodes in the editor so you can visually adjust spawn points without digging into code.
• NEVER check wave completion by counting children every frame — It's too expensive. Maintain a local counter or use a signal-based system to track active enemy counts.

---

Available Scripts

MANDATORY: Read the appropriate script before implementing the corresponding pattern.

wave_loop_patterns.gd

10 Expert patterns: MultiMesh swarms, async pathfinding, background preloading, and server-side physics mobs.

wave_manager.gd

Orchestrates the timeline, delays between waves, and tracks clear via group counts + signals. Uses call_deferred add_child; optional pool via use_pool / recycle_enemy.

wave_resource.gd

Data containers for wave compositions and difficulty settings.

wave_spawner.gd

Marker3D spatial portal — get_spawn_position() with optional radius jitter. Wire as WaveManager.spawner.

wave_weighted_spawner.gd

Weighted random enemy selection at a Marker. Use when composition variety is probability-driven rather than fixed counts.

---

Expert Wave Patterns

1. Occlusion Culling for Swarms

To optimize performance with hundreds of enemies, enable Occlusion Culling.

• Setup: Add an OccluderInstance3D to your arena and bake it.
• Result: Enemies completely hidden behind walls/pillars won't be processed by the GPU, significantly boosting FPS.

2. Wave UI Architecture

Decouple your wave data from the UI using a CanvasLayer and signals.

• Wave Counter: Display current/total waves.
• Health Bars: Use a TextureProgressBar on a CanvasLayer for bosses, or Sprite3D with a viewport texture for individual enemy health bars.

Expert knowledge (on demand)

LLM-ignorance rule: If a general agent would not know it before reading, load the reference — never delete expert deltas.

• wave-expert-patterns.md — restored baseline pedagogy (architecture, WHY, implementation depth)

Reference

Progressive disclosure: open Official Documentation links only when researching a specific API; load Related Skills when routing to a peer domain — do not preload the whole lattice.

Official Documentation

• Resources — WaveResource compositions and delays stay designer-editable without hardcoding spawn tables in managers.
• Nodes and scene instances — PackedScene.instantiate() plus add_child / call_deferred is the safe spawn path for wave enemies.
• Groups — track live mobs with StringName groups and get_node_count_in_group instead of scanning children every frame.
• Idle and Physics Processing — keep pacing on timers/await; never instantiate mid-physics callback without deferring.
• SceneTreeTimer — pre-wave delays and spawn-rate gaps via create_timer without a forever _process countdown.
• Using signals — wave_started / wave_cleared / all_waves_complete decouple UI, audio, and combat from the manager timeline.
• Background loading — ResourceLoader.load_threaded_request bosses/heavy waves so first spawn does not hitch.
• Random number generation — weighted composition and spawn jitter with RandomNumberGenerator.rand_weighted.
• Using MultiMesh — batch swarm visuals when hundreds of minions would explode draw calls.
• Occlusion culling — hide off-camera arena mobs so dense waves stay GPU-affordable.
• Navigation introduction (3D) — async agent paths and separate maps for flying vs walking wave units.
• Using Servers — PhysicsServer3D/NavigationServer3D RID swarms when SceneTree nodes cannot scale.

Related Skills

Prerequisites

• godot-project-foundations — scene tree, exports, and groups before wiring a WaveManager into an arena.
• godot-gdscript-mastery — typed await, signals, and call_deferred patterns the async wave trigger depends on.
• godot-resource-data-patterns — Resource/@export composition and duplicate_deep so spawned mobs do not share stats.

Complements

• godot-signal-architecture — ownership of wave/UI/combat signals so countdown and clear events stay leak-free.
• godot-combat-system — hitboxes, death, and damage that decrement active-enemy counters when a wave unit dies.
• godot-navigation-pathfinding — NavigationServer queries, avoidance masks, and maps for pathing hundreds of wave agents.
• godot-scene-management — pools, threaded loads, and safe add/remove when waves churn PackedScenes.
• godot-performance-optimization — MultiMesh, occlusion, and server-side bodies for swarm density budgets.
• godot-monte-carlo-balancer — style-matrix sampling of spawn counts, rates, and difficulty curves before shipping endless modes.

Downstream / consumers

• godot-genre-tower-defense — lane/portal waves driven by WaveResource sequences and clear-win conditions.
• godot-genre-shooter — arena/horde spawn pacing and enemy variety for wave shooters.
• godot-genre-survival — endless multiplier waves and pressure ramps built on the same manager loop.

Master

• godot-master — library router and mirrored module entry for cross-skill discovery.