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Author SHA1 Message Date
Arkadiusz Sygulski 85def73bd9 Pathfinding Refinement (#2878)
# Pathfinding pt. 3

## Description:

This PR introduces final change to the pathfinding - path refinement. It
optimizes Line of Sight refinement by searching with for the best tile
with a binary search instead of linearly. And then spends the recovered
budget on better refinement of the first and last 50 tiles of the
journey - the place where user is most likely to look at. Additionally
this PR re-introduces magnitude check and makes the ships prefer sailing
close to the coast, but not too close.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## What?

| Before | After |
| :--- | :--- |
| <img width="1097" height="1117" alt="image"
src="https://github.com/user-attachments/assets/4a0b300d-10ef-4151-b6dc-33acfb49f992"
/> | <img width="1093" height="1119" alt="image"
src="https://github.com/user-attachments/assets/cf81c515-c145-40f4-91e5-a4353986907b"
/> |
| <img width="1096" height="1129" alt="image"
src="https://github.com/user-attachments/assets/21b46bce-f961-4259-88f6-fe4a66180270"
/> | <img width="1098" height="1126" alt="image"
src="https://github.com/user-attachments/assets/d92587d1-e6b6-4353-b4a4-1efe71bca43d"
/> |

## Performance

There is actually a severe performance impact of these changes. The path
initial path takes almost 2x as long to generate - this is because pre
processing can only do so much if the initial path is ugly. Luckily in
real gameplay we only need to do this calculation once per edge, so the
actual observed performance impact should be much smaller. Cache FTW.

| | No Cache | Cache |
| :--- | :--- | :--- |
| Before | 277.04ms | 208.58ms |
| After | 498.34ms | 264.27ms |

## DebugSpan

Small utility, it allows any code to be easily instrumented for
performance. The idea is the same as with [OTEL
Spans](https://opentelemetry.io/docs/concepts/signals/traces/). Produce
a span, create sub-spans, measure whatever you need. Works only when
`globalThis.__DEBUG_SPAN_ENABLED__ === true`, otherwise no-op.

Cool stuff, try it out:
```ts
// Convenient wrapper, small performance impact
return DebugSpan.wrap('add', () => a + b)

// Synchronous API, basically free
DebugSpan.start('work')
work()
DebugSpan.end()

// Create sub spans
DebugSpan.wrap('complex', () => {
  const aPlusB = DebugSpan.wrap('add', () => a + b)
  DebugSpan.set('additionResult', () => aPlusB)  // Store data
  return aPlusB * c
})

// Access spans, data and timing
const span = DebugSpan.getLast()
const compelxSpan = DebugSpan.getLast('complex')

console.log(complexSpan.duration, complexSpan.data['additionResult'])
```

These are virtually free and can be enabled on-demand **in production**
and available in the devtools. Under the hood devtools integration is
just a wrapper around [Performance
API](https://developer.mozilla.org/en-US/docs/Web/API/Performance_API).
For clarity data keys not prefixed by `$` are omitted from the
integration. Every key prefixed with `$` must be fully JSON
serializable.

<img width="977" height="799" alt="image"
src="https://github.com/user-attachments/assets/b4d43506-1639-4f78-a611-30e61de12a07"
/>
2026-01-13 12:39:54 -08:00
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