---
name: godot-game-loop-harvest
description: Data-driven resource harvesting system (mining, logging, foraging) for Godot 4. Use when implementing gathering mechanics with tool/tier validation, health depletion, item spawning, and persistence.
---

# Godot Game Loop: Harvest

Implement decoupled, data-driven gathering mechanics. This system handles tool validation, depletion, and respawning.

## 1. Component Reference

| Component | Asset | Description |
| :--- | :--- | :--- |
| **Resource Data** | [resource_data.gd](scripts/resource_data.gd) | `Resource`: Defines health, yield, and tool requirements. |
| **Tool Data** | [harvest_tool_data.gd](scripts/harvest_tool_data.gd) | `Resource`: Defines damage, type, and tier. |
| **Harvestable Node** | [harvestable_node.gd](scripts/harvestable_node.gd) | `StaticBody3D`: The world interaction entity. |
| **Respawn Manager** | [harvest_respawn_manager.gd](scripts/harvest_respawn_manager.gd) | `Node`: (Singleton) Manages world persistence. |
| **Inventory Manager**| [harvest_inventory_manager.gd](scripts/harvest_inventory_manager.gd) | `Node`: Hub for resource collection. |

## 2. Implementation Guide

### Step 1: Resource Setup
- Create a `HarvestResourceData` resource in the inspector.
- Configure `Required Tool Type` (e.g., "pickaxe", "axe") and `Required Tier`.
- Set `Yield Range` (Vector2i) and optional `Item Scene` for physical drops.

### Step 2: Node Configuration
- Attach `harvestable_node.gd` to a `StaticBody3D` node.
- Assign the `ResourceData` from Step 1.
- Assign a child `Node3D` (e.g., a Mesh) to `mesh_to_shake` for visual feedback.
- **Physics**: Ensure the node is on **Layer 1** for interaction.

### Step 3: Global Systems (Recommended)
- Add `harvest_respawn_manager.gd` as an **Autoload** named `HarvestRespawnManager`.
- The `HarvestableNode` will automatically use this manager if it is found at `/root/HarvestRespawnManager`.

## 3. Interaction & Signals

### Calling Hits
When a player interacts (e.g., via RayCast), call `apply_hit(tool_data)`.

```gdscript
if collider is HarvestableNode:
    collider.apply_hit(player_tool)
```

### Signal Map
| Signal | Payload | Integration |
| :--- | :--- | :--- |
| `harvested` | `(data, amount)` | Connect to `InventoryManager.add_resource`. |
| `took_damage` | `(curr, max)` | Connect to a Progress Bar or Damage Popups. |
| `interaction_failed`| `(reason: String)` | Handles `"wrong_tool"` or `"low_tier"` UI feedback. |

## NEVER Do

- **NEVER use float variables to store massively accumulated harvest resources** — Large floats lose precision, which can lead to "missing" resources in idle/clicker games. Always use `int` for core counts.
- **NEVER process gathering logic in _process() without multiplying rates by delta** — If you don't use `delta`, the harvesting speed will fluctuate wildly based on the player's hardware performance/framerate.
- **NEVER run heavy array mathematics for thousands of resources on the main thread** — This will cause micro-stutters. Distribute heavy calculations using `WorkerThreadPool`.
- **NEVER leave a gathering game running at full GPU utilization** — For UI-heavy harvest games, enable `OS.low_processor_usage_mode` to drastically reduce battery drain on mobile/laptops.
- **NEVER trust OS.get_ticks_msec() for offline progress** — This only tracks system uptime. Rely on `Time.get_unix_time_from_system()` to calculate real-world time passed between sessions.
- **NEVER use Timer nodes for precise audio-visual harvesting synchronization** — Timer nodes are subject to framerate variations. For frame-perfect sync, use code-based timers or the animation system.
- **NEVER couple your resource logic directly to UI counters** — Use a signal bus or event system to notify the UI of changes, keeping the game logic decoupled from the presentation.
- **NEVER constantly instantiate and destroy Label nodes for "floating numbers"** — Frequent allocation/deallocation leads to memory fragmentation. Use an object pool for damage/harvest popups.
- **NEVER modify a globally shared Resource without calling duplicate()** — If you modify a shared `Resource` (like a base crop yield), every instance using that resource will be updated. Use `duplicate(true)`.
- **NEVER access shared harvest data from background threads without a Mutex** — Simultaneous access will eventually corrupt your inventory data. Always use a `Mutex` to lock sensitive blocks.
- **NEVER hardcode yield values in your gathering scripts** — Use exports and custom `Resource` files so designers can balance the economy without touching the code.
- **NEVER use queue_free() on a harvested node before the VFX/SFX finish** — You'll cut off the "juice." Hide the mesh and disable collision, then `queue_free()` once the effect signals completion.
- **NEVER check tool requirements via string comparisons if possible** — Use enums or class types. Strings are prone to typos and are slower for high-frequency checks.
- **NEVER neglect to save the UNIX timestamp on exit** — If you forget this, you lose the ability to calculate offline earnings when the player returns.
- **NEVER scale collision shapes non-uniformly for harvestable objects** — This breaks the underlying physics calculations. Adjust the shape resource dimensions instead.

---

## Available Scripts

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

### [harvest_loop_patterns.gd](scripts/harvest_loop_patterns.gd)
Expert patterns for idle optimization, UNIX-based offline gains, and threaded resource processing.

### [resource_data.gd](scripts/resource_data.gd)
`Resource` container: Defines health, yield, and tool requirements for a harvestable object.

### [harvestable_node.gd](scripts/harvestable_node.gd)
`StaticBody3D`: The world interaction entity that handles hits, shakes, and depletion.


---
Source attribution: ahmet-cetinkaya
Original project: https://github.com/ahmet-cetinkaya/dotfiles/blob/d9f3fdbf2e031523a2ac030ab769b095193b5a03/agent-ctrl/profiles/godot/skills/godot-game-loop-harvest/SKILL.md
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Mega AI Hub.

## Upstream license notice

MIT License

Copyright (c) 2026 Ahmet Çetinkaya

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Mega AI Hub resource metadata

Creator / publisher: ahmet-cetinkaya
Original project: https://github.com/ahmet-cetinkaya/dotfiles/blob/d9f3fdbf2e031523a2ac030ab769b095193b5a03/agent-ctrl/profiles/godot/skills/godot-game-loop-harvest/SKILL.md
Attribution basis: Source repository record

Fields of work: Development & Engineering, Product Management
Roles: Game Developer, Product Manager
Specialties: Backend
Tools: Godot
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: 5f2f529c391df401a30a4244f7cd7512b0b275f341645ecf6cfc16fc9d97341f