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Arkadiusz Sygulski
b090f2f624
## Pathfinding with HPA*
Hi! The primary objective of this PR is to replace per-tile A* with
hierarchical pathfinding - HPA*. In practice, this means we create an
abstract graph on top of the actual map with far fewer points and use it
to decide on general path structure. Only then we go back to tile-level
and build path between selected waypoints. This speeds up long distance
pathfinding by over 1000x in some cases. To make the review easier, it
comes with a benchmark and visual playground.
## PREPROCESSING
H part of HPA* means "hierarchical" and requires preprocessing.
This PR includes pre-processing as part inside `new Game()` constructor.
It takes about 135ms for `giantworldmap` on my machine, which increases
the effective initialization from ~95ms to ~230ms. This time could be
reduced in different ways, which are **out of scope** for this PR.
After confirming the initialization time is bearable on low-end devices,
I argue merging this PR as-is is acceptable tradeoff. It creates small
lag at the beginning of a round but pays for itself in the first minute
of the match.
## Nerdy details
**Architecture**
- HPA*-style hierarchical pathfinding
- 32×32 sectors on minimap with gateway nodes on borders
- Gateway graph built via BFS during preprocessing
- Water component optimization skips unreachable gateway pairs
- A* on gateway graph → local A* within sectors → Bresenham path
smoothing
- Minimap upscaling identical to currently used in MiniAStar
**Key Optimizations**
- Typed arrays instead of high-level primitives
- Stamp-based visited tracking (no need to recreate buffers, O(1)
clearing)
- Optional - enabled by default - caching of tile paths between gateways
- Line of sight smoothing for the final path
## Review Focus
Play with included tools, benchmark and visualization. Pathfinding
should be safe to merge as a black box - you do not need to understand
the details. Outcomes can be tested empirically in-game. Visualize (and
share!) edge cases with included playground. Confirm the 100x speedup is
real with benchmark.
If you plan to dive into the code, I suggest the following order:
- Pathfinding abstraction in `src/core/pathfinding/`
- Pathfinding tests in `tests/core/pathfinding/`
- NavMesh in `src/core/pathfinding/navmesh/` + integration with
`Game.ts`
- Benchmark in `tests/pathfinding/benchmark/`
Do not look at playground's code, it has been created with a clanker.
The design is 100% mine and I spent way too long polishing it, but I
haven't even once edited the code manually. There is probably no
abstraction whatsoever, just do not look at the code, let it play.
## Core Changes
#### Pathfinding (`src/core/pathfinding/navmesh/`)
- HPA* + refinement -> three phased pathfinding: A* over the graph ->
naive path -> refinement
- comes with A* and BFS optimized for for specific needs
#### Pre-Processing (`src/core/pathfinding/navmesh/`)
- identify water bodies to avoid pathfinding between disconnected nodes
- create high-level graph of gateways on top of tile map
#### Abstraction (`src/core/pathfinding/`)
- common `PathFinder` interface that can return full path and also act
as state machine (`.next()`)
- adapters for both new and legacy algorithm with fallback to legacy if
navigation mesh not available
#### Benchmark (`tests/pathfinding/benchmark/`)
- `npx tsx tests/pathfinding/benchmark/run.ts` - no guesswork, numbers
- `npx tsx tests/pathfinding/benchmark/run.ts --synthetic` - 1000s of
synthetic paths
- `npx tsc tests/pathfinding/benchmark/generate.ts` - generate more as
needed, test new maps
- includes ONE synthetic scenario to avoid PR bloat, generate more
locally / later
#### Playground (`tests/pathfinding/playground/`)
- `npx tsx tests/pathfinding/playground/server.ts` - visualize paths
with both new and legacy algorithm
## Benchmarks
### Compared with legacy in default - hand picked - scenario:
```
Initialization: 95.95ms -> 227.29ms
Pathfinding: 3038.43ms -> 6.45ms
Distance: 26972 -> 26810 tiles
```
### 42,000 synthetic routes across all maps
```
Running 42 synthetic scenarios with hpa.cached adapter...
✅ synthetic/achiran | Init: 93.42ms | Path: 139.07ms | Dist: 1481630 tiles | Routes: 1000/1000
✅ synthetic/africa | Init: 87.14ms | Path: 155.08ms | Dist: 1829414 tiles | Routes: 1000/1000
✅ synthetic/asia | Init: 57.60ms | Path: 112.55ms | Dist: 1204082 tiles | Routes: 1000/1000
✅ synthetic/australia | Init: 78.18ms | Path: 77.12ms | Dist: 978375 tiles | Routes: 1000/1000
✅ synthetic/baikal | Init: 78.26ms | Path: 152.14ms | Dist: 1600016 tiles | Routes: 1000/1000
✅ synthetic/baikalnukewars | Init: 81.44ms | Path: 165.90ms | Dist: 1699283 tiles | Routes: 1000/1000
✅ synthetic/betweentwoseas | Init: 29.29ms | Path: 114.99ms | Dist: 1338075 tiles | Routes: 1000/1000
✅ synthetic/blacksea | Init: 30.66ms | Path: 93.14ms | Dist: 949217 tiles | Routes: 1000/1000
✅ synthetic/britannia | Init: 74.12ms | Path: 85.62ms | Dist: 866752 tiles | Routes: 1000/1000
✅ synthetic/deglaciatedantarctica | Init: 105.49ms | Path: 192.93ms | Dist: 1574684 tiles | Routes: 1000/1000
✅ synthetic/didier | Init: 81.51ms | Path: 153.70ms | Dist: 1734876 tiles | Routes: 1000/1000
✅ synthetic/eastasia | Init: 49.29ms | Path: 128.63ms | Dist: 1410270 tiles | Routes: 1000/1000
✅ synthetic/europe | Init: 92.55ms | Path: 178.35ms | Dist: 1525216 tiles | Routes: 1000/1000
✅ synthetic/europeclassic | Init: 33.50ms | Path: 104.40ms | Dist: 1209759 tiles | Routes: 1000/1000
✅ synthetic/falklandislands | Init: 63.00ms | Path: 107.41ms | Dist: 1080251 tiles | Routes: 1000/1000
✅ synthetic/faroeislands | Init: 71.91ms | Path: 49.52ms | Dist: 604613 tiles | Routes: 1000/1000
✅ synthetic/fourislands | Init: 45.75ms | Path: 78.91ms | Dist: 937439 tiles | Routes: 1000/1000
✅ synthetic/gatewaytotheatlantic | Init: 81.00ms | Path: 257.06ms | Dist: 2555551 tiles | Routes: 1000/1000
✅ synthetic/giantworldmap | Init: 214.25ms | Path: 220.42ms | Dist: 1976693 tiles | Routes: 1000/1000
✅ synthetic/gulfofstlawrence | Init: 45.16ms | Path: 96.05ms | Dist: 1014604 tiles | Routes: 1000/1000
✅ synthetic/halkidiki | Init: 74.68ms | Path: 149.39ms | Dist: 1546781 tiles | Routes: 1000/1000
✅ synthetic/iceland | Init: 58.72ms | Path: 78.16ms | Dist: 1001554 tiles | Routes: 1000/1000
✅ synthetic/italia | Init: 29.78ms | Path: 139.93ms | Dist: 1412024 tiles | Routes: 1000/1000
✅ synthetic/japan | Init: 161.07ms | Path: 118.65ms | Dist: 1154393 tiles | Routes: 1000/1000
✅ synthetic/lemnos | Init: 52.59ms | Path: 136.69ms | Dist: 1481101 tiles | Routes: 1000/1000
✅ synthetic/lisbon | Init: 49.27ms | Path: 86.53ms | Dist: 1032011 tiles | Routes: 1000/1000
✅ synthetic/manicouagan | Init: 53.74ms | Path: 110.52ms | Dist: 1307630 tiles | Routes: 1000/1000
✅ synthetic/mars | Init: 29.39ms | Path: 80.55ms | Dist: 1091702 tiles | Routes: 1000/1000
✅ synthetic/mena | Init: 26.37ms | Path: 120.09ms | Dist: 1272751 tiles | Routes: 1000/1000
✅ synthetic/montreal | Init: 26.08ms | Path: 106.77ms | Dist: 1187736 tiles | Routes: 1000/1000
✅ synthetic/newyorkcity | Init: 56.60ms | Path: 181.19ms | Dist: 1753875 tiles | Routes: 1000/1000
✅ synthetic/northamerica | Init: 96.29ms | Path: 123.02ms | Dist: 1217221 tiles | Routes: 1000/1000
✅ synthetic/oceania | Init: 52.81ms | Path: 51.96ms | Dist: 482373 tiles | Routes: 1000/1000
✅ synthetic/pangaea | Init: 21.29ms | Path: 56.58ms | Dist: 716189 tiles | Routes: 1000/1000
✅ synthetic/pluto | Init: 53.89ms | Path: 141.62ms | Dist: 1304362 tiles | Routes: 1000/1000
✅ synthetic/southamerica | Init: 85.19ms | Path: 123.03ms | Dist: 1301403 tiles | Routes: 1000/1000
✅ synthetic/straitofgibraltar | Init: 76.68ms | Path: 108.30ms | Dist: 1304592 tiles | Routes: 1000/1000
✅ synthetic/straitofhormuz | Init: 38.97ms | Path: 67.78ms | Dist: 754920 tiles | Routes: 1000/1000
✅ synthetic/surrounded | Init: 95.35ms | Path: 90.18ms | Dist: 1017142 tiles | Routes: 1000/1000
✅ synthetic/svalmel | Init: 60.58ms | Path: 104.75ms | Dist: 1235501 tiles | Routes: 1000/1000
✅ synthetic/twolakes | Init: 62.05ms | Path: 94.54ms | Dist: 1140807 tiles | Routes: 1000/1000
✅ synthetic/world | Init: 41.43ms | Path: 93.42ms | Dist: 873406 tiles | Routes: 1000/1000
Completed 42 scenarios
Total Initialization Time: 2796.32ms
Total Pathfinding Time: 5026.64ms
Total Distance: 53160274 tiles
```
## Playground
**That's the fun part**. Watch NavMesh running circles around legacy
`PathFinder.Mini` in real time. Debug inner workings, test edge cases,
share URLs for debugging.
https://github.com/user-attachments/assets/34e2e3f5-fbc1-4b1f-917d-820766e98d5d
## Discord Tag
`moleole`
OpenFront.io is an online real-time strategy game focused on territorial control and alliance building. Players compete to expand their territory, build structures, and form strategic alliances in various maps based on real-world geography.
This is a fork/rewrite of WarFront.io. Credit to https://github.com/WarFrontIO.
License
OpenFront source code is licensed under the GNU Affero General Public License v3.0
Current copyright notices appear in:
- Footer: "© OpenFront and Contributors"
- Loading screen: "© OpenFront and Contributors"
Modified versions must preserve these notices in reasonably visible locations.
See the LICENSE for complete requirements.
For asset licensing, see LICENSE-ASSETS.
For license history, see LICENSING.md.
🌟 Features
- Real-time Strategy Gameplay: Expand your territory and engage in strategic battles
- Alliance System: Form alliances with other players for mutual defense
- Multiple Maps: Play across various geographical regions including Europe, Asia, Africa, and more
- Resource Management: Balance your expansion with defensive capabilities
- Cross-platform: Play in any modern web browser
📋 Prerequisites
- npm (v10.9.2 or higher)
- A modern web browser (Chrome, Firefox, Edge, etc.)
🚀 Installation
-
Clone the repository
git clone https://github.com/openfrontio/OpenFrontIO.git cd OpenFrontIO -
Install dependencies
npm run instDo NOT use
npm installnornpm ibut instead use ournpm run inst. It runs the safernpm ci --ignore-scriptsto install dependencies exactly according to the versions inpackage-lock.jsonand doesn't run scripts. This can prevent being hit by a supply chain attack.
🎮 Running the Game
Development Mode
Run both the client and server in development mode with live reloading:
npm run dev
This will:
- Start the webpack dev server for the client
- Launch the game server with development settings
- Open the game in your default browser (to disable this behavior, set
SKIP_BROWSER_OPEN=truein your environment)
Client Only
To run just the client with hot reloading:
npm run start:client
Server Only
To run just the server with development settings:
npm run start:server-dev
Connecting to staging or production backends
Sometimes it's useful to connect to production servers when replaying a game, testing user profiles, purchases, or login flow.
To replay a production game, make sure you're on the same commit that the game you want to replay was executed on, you can find the
gitCommitvalue viahttps://api.openfront.io/game/[gameId]. Unfinished games cannot be replayed on localhost.
To connect to staging api servers:
npm run dev:staging
To connect to production api servers:
npm run dev:prod
🛠️ Development Tools
-
Format code:
npm run format -
Lint code:
npm run lint -
Lint and fix code:
npm run lint:fix -
Testing
npm test
🏗️ Project Structure
/src/client- Frontend game client/src/core- Shared game logic/src/server- Backend game server/resources- Static assets (images, maps, etc.)
🤝 Contributing
Contributions are welcome! Please feel free to submit a Pull Request.
- Request to join the development Discord.
- Fork the repository
- Create your feature branch (
git checkout -b amazing-feature) - Commit your changes (
git commit -m 'Add some amazing feature') - Push to the branch (
git push origin amazing-feature) - Open a Pull Request
🌐 Translation
Translators are welcome! Please feel free to help translate into your language. How to help?
- Join the translation Discord
- Go to the project's Crowdin translation page: https://crowdin.com/project/openfront-mls
- Login if you already have an account / Sign up if you don't have one
- Join the project
- Select the language you want to translate in. If your language isn't on the list, click the "Request New Language" button and enter the language you want added there.
- Translate the strings
Feel free to ask questions in the translation Discord server!
Project Governance
- The project maintainer (evan) has final authority on all code changes and design decisions
- All pull requests require maintainer approval before merging
- The maintainer reserves the right to reject contributions that don't align with the project's vision or quality standards
Contribution Path for New Contributors
To ensure code quality and project stability, we use a progressive contribution system:
-
New Contributors: Limited to UI improvements and small bug fixes only
- This helps you become familiar with the codebase
- UI changes are easier to review and less likely to break core functionality
- Small, focused PRs have a higher chance of being accepted
-
Established Contributors: After several successful PRs and demonstrating understanding of the codebase, you may work on more complex features
-
Core Contributors: Only those with extensive experience with the project may modify critical game systems
How to Contribute Successfully
-
Before Starting Work:
- Open an issue describing what you want to contribute
- Wait for maintainer feedback before investing significant time
- Small improvements can proceed directly to PR stage
-
Code Quality Requirements:
- All code must be well-commented and follow existing style patterns
- New features should not break existing functionality
- Code should be thoroughly tested before submission
- All code changes in src/core MUST be tested.
-
Pull Request Process:
- Keep PRs focused on a single feature or bug fix
- Include screenshots for UI changes
- Describe what testing you've performed
- Be responsive to feedback and requested changes
-
Testing Requirements:
- Verify your changes work as expected
- Test on multiple systems/browsers if applicable
- Document your testing process in the PR
Communication
- Be respectful and constructive in all project interactions
- Questions are welcome, but please search existing issues first
- For major changes, discuss in an issue before starting work
Final Notes
Remember that maintaining this project requires significant effort. The maintainer appreciates your contributions but must prioritize long-term project health and stability. Not all contributions will be accepted, and that's okay.
Thank you for helping make OpenFront better!