Files
Arkadiusz Sygulski b090f2f624 HPA* Pathfinding (#2815)
## 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`
2026-01-08 13:34:18 -08:00

225 lines
5.8 KiB
TypeScript

import { readdirSync, readFileSync } from "fs";
import { dirname, join } from "path";
import { fileURLToPath } from "url";
import { Game } from "../../../../src/core/game/Game.js";
import { TileRef } from "../../../../src/core/game/GameMap.js";
import { NavMesh } from "../../../../src/core/pathfinding/navmesh/NavMesh.js";
import { setupFromPath } from "../../utils.js";
export interface MapInfo {
name: string;
displayName: string;
}
export interface MapCache {
game: Game;
navMesh: NavMesh;
}
const cache = new Map<string, MapCache>();
/**
* Global configuration for map loading
*/
let config = {
cachePaths: true,
};
/**
* Set configuration options
*/
export function setConfig(options: { cachePaths?: boolean }) {
config = { ...config, ...options };
}
/**
* Get the resources/maps directory path
*/
function getMapsDirectory(): string {
return join(
dirname(fileURLToPath(import.meta.url)),
"../../../../resources/maps",
);
}
/**
* Format map name to title case with proper spacing
* Handles: underscores, camelCase, existing spaces, and parentheses
*/
function formatMapName(name: string): string {
return (
name
// Replace underscores with spaces
.replace(/_/g, " ")
// Add space before capital letters (for camelCase)
.replace(/([a-z])([A-Z])/g, "$1 $2")
// Convert to lowercase first
.toLowerCase()
// Capitalize first letter of string
.replace(/^\w/, (char) => char.toUpperCase())
// Capitalize after spaces and opening parentheses
.replace(/(\s+|[(])\w/g, (match) => match.toUpperCase())
);
}
/**
* Get list of available maps by reading the resources/maps directory
*/
export function listMaps(): MapInfo[] {
const mapsDir = getMapsDirectory();
const maps: MapInfo[] = [];
try {
const entries = readdirSync(mapsDir, { withFileTypes: true });
for (const entry of entries) {
if (entry.isDirectory()) {
const name = entry.name;
let displayName = formatMapName(name);
// Try to read displayName from manifest.json
try {
const manifestPath = join(mapsDir, name, "manifest.json");
const manifestData = JSON.parse(readFileSync(manifestPath, "utf-8"));
if (manifestData.name) {
displayName = formatMapName(manifestData.name);
}
} catch (e) {
// If manifest doesn't exist or doesn't have name, use formatted folder name
console.warn(
`Could not read manifest for ${name}:`,
e instanceof Error ? e.message : e,
);
}
maps.push({ name, displayName });
}
}
} catch (e) {
console.error("Failed to read maps directory:", e);
}
return maps.sort((a, b) => a.displayName.localeCompare(b.displayName));
}
/**
* Load a map from cache or disk
*/
export async function loadMap(mapName: string): Promise<MapCache> {
// Check cache first
if (cache.has(mapName)) {
return cache.get(mapName)!;
}
const mapsDir = getMapsDirectory();
// Use the existing setupFromPath utility to load the map
const game = await setupFromPath(mapsDir, mapName);
// Initialize NavMesh
const navMesh = new NavMesh(game, { cachePaths: config.cachePaths });
navMesh.initialize();
const cacheEntry: MapCache = { game, navMesh };
// Store in cache
cache.set(mapName, cacheEntry);
return cacheEntry;
}
/**
* Get map metadata for client
*/
export async function getMapMetadata(mapName: string) {
const { game, navMesh } = await loadMap(mapName);
// Extract map data
const mapData: number[] = [];
for (let y = 0; y < game.height(); y++) {
for (let x = 0; x < game.width(); x++) {
const tile = game.ref(x, y);
mapData.push(game.isWater(tile) ? 1 : 0);
}
}
// Extract static graph data from NavMesh
const miniMap = game.miniMap();
const navMeshGraph = (navMesh as any).graph;
// Convert gateways from Map to array
const gatewaysArray = Array.from(navMeshGraph.gateways.values());
const allGateways = gatewaysArray.map((gw: any) => ({
id: gw.id,
x: miniMap.x(gw.tile),
y: miniMap.y(gw.tile),
}));
// Create a lookup map from gateway ID to gateway for edge conversion
const gatewayById = new Map(gatewaysArray.map((gw: any) => [gw.id, gw]));
// Convert edges from Map<gatewayId, Edge[]> to flat array
// The edges Map has gateway IDs as keys, and arrays of edges as values
const allEdges: any[] = [];
for (const edgeArray of navMeshGraph.edges.values()) {
allEdges.push(...edgeArray);
}
// Deduplicate edges (they're bidirectional, so each edge appears twice)
const seenEdges = new Set<string>();
const edges = allEdges
.filter((edge: any) => {
const edgeKey =
edge.from < edge.to
? `${edge.from}-${edge.to}`
: `${edge.to}-${edge.from}`;
if (seenEdges.has(edgeKey)) return false;
seenEdges.add(edgeKey);
return true;
})
.map((edge: any) => {
const fromGateway = gatewayById.get(edge.from);
const toGateway = gatewayById.get(edge.to);
return {
fromId: edge.from,
toId: edge.to,
from: fromGateway
? [miniMap.x(fromGateway.tile) * 2, miniMap.y(fromGateway.tile) * 2]
: [0, 0],
to: toGateway
? [miniMap.x(toGateway.tile) * 2, miniMap.y(toGateway.tile) * 2]
: [0, 0],
cost: edge.cost,
path: edge.path
? edge.path.map((tile: TileRef) => [game.x(tile), game.y(tile)])
: null,
};
});
console.log(
`Map ${mapName}: ${allGateways.length} gateways, ${edges.length} edges`,
);
const sectorSize = navMeshGraph.sectorSize;
return {
name: mapName,
width: game.width(),
height: game.height(),
mapData,
graphDebug: {
allGateways,
edges,
sectorSize,
},
};
}
/**
* Clear map cache
*/
export function clearCache() {
cache.clear();
}