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OpenFrontIO/tests/pathfinding
Arkadiusz Sygulski 0e3ced3bfa Pathfinding Refactor pt. 2 (#2866)
## Playtest

https://pf-pt-2.openfront.dev/

## Pathfinding Refactor pt. 2

<img width="1536" height="1024" alt="image"
src="https://github.com/user-attachments/assets/9477958e-54b7-4c83-b317-ba789e809e9e"
/>


This is a follow-up to a previous PR introducing pathfinding changes.
This time, it introduces a complete refactor of `pathfinding` directory
and breakdown into composable pieces.

### Unified PathFinder interface

`PathFinder<T>` and `SteppingPathFinder<T>` are introduced to unify
**all** pathfinding across the application. First one exposes complete
path, while stepping variant allows the callee to iterate over the path
by calling `.next`. All pathfinders share this one common interface,
which makes them easy to use in any scenario -
`PathFinding.Water(game).search(from, to)`.

`SteppingPathFinder<T>` extends `PathFinder<T>` with an ability to
iterate over the path. It handles caching, storing current index and
invalidation. This allows the units to not care about the inner workings
of the pathfinder and just call `pf.next(current, target)` and receive
instructions on what to do next.

### Common entry point

All pathfinders are now exposed from common `PathFinding` entrypoint:

- `PathFinding.Water`
- `PathFinding.Rail`
- `PathFinding.Stations`
- `PathFinding.Rail`

Additional entry point is introduced for pathfinders which need to work
both in the worker, but also on the frontend, which lacks `Game`
interface. Currently only `UniversalPathFinding.Parabola` is available.

### Spatial Query

New module has been introduced close to `pathfinding` - `SpatialQuery`.
It aims to resolve any questions game may have about finding tiles
meeting criteria. Currently `SpatialQuery.closestShore(player, target)`
and `SpatialQuery.closestShoreByWater(player, target)` are available -
they help answering questions about naval invasion: "What is the best
landing location from user's click?" and "Which our tile should be used
to launch the transport ship?". Under the hood they use very similar
mechanics to pathfinding, so it felt right to put them close by.

### Modular architecture

Pathfinders now support transformers: `MiniMapTransformer`,
`ShoreCoercingTransformer`, `ComponentCheckTransformer`,
`SmoothingTransformer`. Transformers functions like a middleware in the
pathfinding chain. They wrap around the pathfinder and provide
additional functionality. This allows the pathfinder to focus on
actually finding the path instead of doing unrelated things.

Example chain for simple (A*) water pathfinding:
```ts
static WaterSimple(game: Game): SteppingPathFinder<TileRef> {
  const miniMap = game.miniMap();
  const pf = new AStarWater(miniMap);

  return PathFinderBuilder.create(pf)
    .wrap((pf) => new ShoreCoercingTransformer(pf, miniMap))
    .wrap((pf) => new MiniMapTransformer(pf, game.map(), miniMap))
    .buildWithStepper(tileStepperConfig(game));
}
```

The Pathfinder - here `AStarWater` - does not care about the conversion
between minimap and main map tiles. It also does not care if the source
or destination is a land tile. The transformers take care of that. The
pathfinder gets a set of valid coordinates and produces the path -
that's it.

Modular approach makes working on a particular set of utilities much
easier - for example map upscaling is handled consistently across all
pathfinders. Additionally, the pathfinders are not tied to the
particular map resolution used. Pass them a different map and they will
work the same.

### Algorithms

Algorithms used are neatly organized inside
`src/core/pathfinding/algorithms`. They are prefixed with the algorithm
name and suffixed with the use case. File without suffix exposes generic
version ready to traverse any graph with adapters. Specialized versions
either use an adapter or inline logic when performance is critical -
using adapters leads to 20-30% performance loss.

The directory includes `A*` and `BFS` but also other useful utils, such
as `AbstractGraph` used to generate... an abstract graph on top of the
tile map and `ConnectedComponents` helping to identify whether two tiles
are connected by a path without actually computing the path.

### Playground

The playground have been updated with new algorithms, including tweaked
very greedy `A*`.

<img width="2175" height="1424" alt="image"
src="https://github.com/user-attachments/assets/1f833651-0024-4299-bf86-882f5368358c"
/>

### Tests

Yeah, there are some, a little too many if I say so myself. But there
are no useless tests. I had to ensure refactored code works somehow
reliably. This PR comes with trust me bro guarantee, but I would
appreciate someone confirming **naval invasions, nukes (esp. MIRV) and
warships**.

### Discord
`moleole`

GL & HF
2026-01-11 20:11:14 -08:00
..
2026-01-08 13:34:18 -08:00
2026-01-11 20:11:14 -08:00

Pathfinding Tests

This directory contains benchmarking tools, scenario generators, and an interactive playground for testing and optimizing pathfinding algorithms in OpenFrontIO.

TLDR

npx tsx tests/pathfinding/benchmark/run.ts --synthetic --all
npx tsx tests/pathfinding/playground/server.ts

Directory Structure

tests/pathfinding/
├── benchmark.ts          # Benchmarking tool
├── scenarios/            # Scenarios for benchmarks
│   ├── default.ts        # Hand-picked scenario
│   └── synthetic/        # Auto-generated synthetic scenarios
└── playground/           # Interactive web-based visualization

Available algorithms

  • NavSat - future implementation - NavigationSatellite (HPA*)
  • PF.Mini - current implementation - PathFinder.Mini (A*)

Benchmarking

Running a Single Scenario

# Run default scenario with default adapter (NavSat)
npx tsx tests/pathfinding/benchmark/run.ts

# Run specific scenario
npx tsx tests/pathfinding/benchmark/run.ts default

# Run with specific adapter
npx tsx tests/pathfinding/benchmark/run.ts default legacy

Running Synthetic Scenarios

Synthetic scenarios are auto-generated from maps with random port selections and routes.

# Run single synthetic scenario
npx tsx tests/pathfinding/benchmark/run.ts --synthetic iceland

# Run single synthetic scenario with specific adapter
npx tsx tests/pathfinding/benchmark/run.ts --synthetic iceland legacy

# Run ALL synthetic scenarios (comprehensive benchmark)
npx tsx tests/pathfinding/benchmark/run.ts --synthetic --all

# Run all with specific adapter
npx tsx tests/pathfinding/benchmark/run.ts --synthetic --all legacy

Benchmark Metrics

The benchmark measures three key metrics:

  1. Initialization Time - How long it takes to preprocess the map
  2. Path Distance - Total distance across all routes (quality metric)
  3. Pathfinding Time - How long it takes to compute paths (performance metric)

Example Output

================================================================================
METRIC 1: INITIALIZATION TIME
================================================================================

Initialization time: 45.32ms

================================================================================
METRIC 2: PATH DISTANCE
================================================================================

Route                                    Path Length
Miami → Boston                           346 tiles
Miami → Houston                          212 tiles
...

Total distance: 52432 tiles
Routes completed: 22 / 22

================================================================================
METRIC 3: PATHFINDING TIME
================================================================================

Route                                    Time
Miami → Boston                           2.45ms
Miami → Houston                          1.82ms
...

Total time: 156.34ms
Average time: 7.11ms
Routes benchmarked: 22 / 22

================================================================================
SUMMARY
================================================================================

Adapter: default
Scenario: default

Scores:
  Initialization: 45.32ms
  Pathfinding: 156.34ms
  Distance: 52432 tiles

Generating Scenarios

Generate Synthetic Scenarios

Synthetic scenarios are generated by:

  1. Finding all water shoreline tiles on a map
  2. Randomly selecting 200 ports
  3. Creating 1000 routes connecting nearby ports
# Generate scenario for a single map
npx tsx tests/pathfinding/benchmark/generate.ts iceland

# Generate scenarios for all maps
npx tsx tests/pathfinding/benchmark/generate.ts --all

# Force overwrite existing scenarios
npx tsx tests/pathfinding/benchmark/generate.ts iceland --force
npx tsx tests/pathfinding/benchmark/generate.ts --all --force

Interactive Playground

The playground provides a web-based UI for visualizing pathfinding results, comparing algorithms, and debugging.

Starting the Playground

# Start with path caching enabled (default)
npx tsx tests/pathfinding/playground/server.ts

# Start without path caching (to measure uncached performance)
npx tsx tests/pathfinding/playground/server.ts --no-cache

Then open http://localhost:5555 in your browser.