Add neat arena

This commit is contained in:
Peter Stockings
2026-01-12 08:58:45 +11:00
parent e9cb8b52df
commit 840e597413
39 changed files with 5717 additions and 193 deletions

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import Phaser from 'phaser';
import type { SimulationState } from './types';
import { SIMULATION_CONFIG } from './types';
/**
* Phaser scene for rendering the NEAT Arena.
*
* This scene is ONLY for visualization - the actual simulation runs separately.
* The scene receives simulation state updates and renders them.
*/
export class ArenaScene extends Phaser.Scene {
private simulationState: SimulationState | null = null;
private showRays: boolean = true;
// Graphics objects
private wallGraphics!: Phaser.GameObjects.Graphics;
private agentGraphics!: Phaser.GameObjects.Graphics;
private bulletGraphics!: Phaser.GameObjects.Graphics;
private rayGraphics!: Phaser.GameObjects.Graphics;
constructor() {
super({ key: 'ArenaScene' });
}
create() {
// Create graphics layers (back to front)
this.wallGraphics = this.add.graphics();
this.rayGraphics = this.add.graphics();
this.bulletGraphics = this.add.graphics();
this.agentGraphics = this.add.graphics();
// Set background
this.cameras.main.setBackgroundColor(0x1a1a2e);
}
update() {
if (!this.simulationState) return;
this.render();
}
/**
* Update the simulation state to render
*/
public updateSimulation(state: SimulationState) {
this.simulationState = state;
}
/**
* Toggle ray visualization
*/
public setShowRays(show: boolean) {
this.showRays = show;
}
/**
* Render the current simulation state
*/
private render() {
if (!this.simulationState) return;
// Clear graphics
this.wallGraphics.clear();
this.agentGraphics.clear();
this.bulletGraphics.clear();
this.rayGraphics.clear();
// Render walls
this.renderWalls();
// Render rays (if enabled)
if (this.showRays) {
this.renderRays();
}
// Render bullets
this.renderBullets();
// Render agents
this.renderAgents();
}
private renderWalls() {
if (!this.simulationState) return;
const { walls } = this.simulationState.map;
this.wallGraphics.fillStyle(0x4a5568, 1);
this.wallGraphics.lineStyle(2, 0x64748b, 1);
for (const wall of walls) {
const { minX, minY, maxX, maxY } = wall.rect;
this.wallGraphics.fillRect(minX, minY, maxX - minX, maxY - minY);
this.wallGraphics.strokeRect(minX, minY, maxX - minX, maxY - minY);
}
}
private renderAgents() {
if (!this.simulationState) return;
const agents = this.simulationState.agents;
const colors = [0x667eea, 0xf093fb]; // Purple and pink
for (let i = 0; i < agents.length; i++) {
const agent = agents[i];
const color = colors[i];
// Agent body (circle)
if (agent.invulnTicks > 0) {
// Flash when invulnerable
const alpha = agent.invulnTicks % 4 < 2 ? 0.5 : 1;
this.agentGraphics.fillStyle(color, alpha);
} else {
this.agentGraphics.fillStyle(color, 1);
}
this.agentGraphics.fillCircle(agent.position.x, agent.position.y, agent.radius);
// Border
this.agentGraphics.lineStyle(2, 0xffffff, 0.8);
this.agentGraphics.strokeCircle(agent.position.x, agent.position.y, agent.radius);
// Aim direction indicator
const aimLength = 20;
const aimEndX = agent.position.x + Math.cos(agent.aimAngle) * aimLength;
const aimEndY = agent.position.y + Math.sin(agent.aimAngle) * aimLength;
this.agentGraphics.lineStyle(3, 0xffffff, 1);
this.agentGraphics.lineBetween(agent.position.x, agent.position.y, aimEndX, aimEndY);
}
}
private renderBullets() {
if (!this.simulationState) return;
this.bulletGraphics.fillStyle(0xfbbf24, 1); // Yellow
this.bulletGraphics.lineStyle(1, 0xffffff, 0.8);
for (const bullet of this.simulationState.bullets) {
this.bulletGraphics.fillCircle(bullet.position.x, bullet.position.y, 3);
this.bulletGraphics.strokeCircle(bullet.position.x, bullet.position.y, 3);
}
}
private renderRays() {
if (!this.simulationState) return;
// TODO: This will be implemented when we integrate sensor visualization
// For now, rays will be rendered when we have a specific agent's observation to display
}
}
/**
* Create and initialize a Phaser game instance for the arena
*/
export function createArenaViewer(parentElement: HTMLElement): Phaser.Game {
const config: Phaser.Types.Core.GameConfig = {
type: Phaser.AUTO,
width: SIMULATION_CONFIG.WORLD_SIZE,
height: SIMULATION_CONFIG.WORLD_SIZE,
parent: parentElement,
backgroundColor: '#1a1a2e',
scene: ArenaScene,
physics: {
default: 'arcade',
arcade: {
debug: false,
},
},
scale: {
mode: Phaser.Scale.FIT,
autoCenter: Phaser.Scale.CENTER_BOTH,
},
};
return new Phaser.Game(config);
}
/**
* Get the scene instance from a Phaser game
*/
export function getArenaScene(game: Phaser.Game): ArenaScene {
return game.scene.getScene('ArenaScene') as ArenaScene;
}

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import type { AgentAction } from './types';
import { SeededRandom } from './utils';
/**
* Baseline scripted bots for testing and benchmarking.
*
* These provide simple strategies that can be used to:
* - Test the simulation mechanics
* - Provide initial training opponents
* - Benchmark evolved agents
*/
/**
* Random bot - takes random actions
*/
export function randomBotAction(rng: SeededRandom): AgentAction {
return {
moveX: rng.nextFloat(-1, 1),
moveY: rng.nextFloat(-1, 1),
turn: rng.nextFloat(-1, 1),
shoot: rng.next(),
};
}
/**
* Idle bot - does nothing
*/
export function idleBotAction(): AgentAction {
return {
moveX: 0,
moveY: 0,
turn: 0,
shoot: 0,
};
}
/**
* Spinner bot - spins in place and shoots
*/
export function spinnerBotAction(): AgentAction {
return {
moveX: 0,
moveY: 0,
turn: 1,
shoot: 1,
};
}
/**
* Circle strafe bot - moves in circles and shoots
*/
export function circleStrafeBotAction(tick: number): AgentAction {
const angle = (tick / 20) * Math.PI * 2;
return {
moveX: Math.cos(angle),
moveY: Math.sin(angle),
turn: 0.3,
shoot: tick % 15 === 0 ? 1 : 0,
};
}

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import type { Genome, InnovationTracker } from './genome';
import { cloneGenome } from './genome';
/**
* NEAT Crossover
*
* Produces offspring by crossing over two parent genomes.
* Follows the NEAT crossover rules:
* - Matching genes are randomly inherited
* - Disjoint/excess genes are inherited from the fitter parent
* - Disabled genes have a chance to stay disabled
*/
const DISABLED_GENE_INHERITANCE_RATE = 0.75;
/**
* Perform crossover between two genomes
* @param parent1 First parent (should be fitter or equal)
* @param parent2 Second parent
* @param innovationTracker Not used in crossover, but kept for consistency
* @returns Offspring genome
*/
export function crossover(
parent1: Genome,
parent2: Genome,
innovationTracker?: InnovationTracker
): Genome {
// Ensure parent1 is fitter (or equal)
if (parent2.fitness > parent1.fitness) {
[parent1, parent2] = [parent2, parent1];
}
const offspring = cloneGenome(parent1);
offspring.connections = [];
offspring.fitness = 0;
// Build innovation maps
const p1Connections = new Map(
parent1.connections.map(c => [c.innovation, c])
);
const p2Connections = new Map(
parent2.connections.map(c => [c.innovation, c])
);
// Get all innovation numbers
const allInnovations = new Set([
...p1Connections.keys(),
...p2Connections.keys(),
]);
for (const innovation of allInnovations) {
const conn1 = p1Connections.get(innovation);
const conn2 = p2Connections.get(innovation);
if (conn1 && conn2) {
// Matching gene - randomly choose from either parent
const chosen = Math.random() < 0.5 ? conn1 : conn2;
const newConn = { ...chosen };
// Handle disabled gene inheritance
if (!conn1.enabled || !conn2.enabled) {
if (Math.random() < DISABLED_GENE_INHERITANCE_RATE) {
newConn.enabled = false;
}
}
offspring.connections.push(newConn);
} else if (conn1) {
// Disjoint/excess gene from parent1 (fitter)
offspring.connections.push({ ...conn1 });
}
// Genes only in parent2 are not inherited (parent1 is fitter)
}
return offspring;
}

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import { InnovationTracker, type Genome } from './genome';
import type { Species } from './speciation';
import type { ReproductionConfig } from './reproduction';
import { createMinimalGenome } from './genome';
import {
speciate,
adjustCompatibilityThreshold,
applyFitnessSharing,
DEFAULT_COMPATIBILITY_CONFIG,
type CompatibilityConfig,
} from './speciation';
import { reproduce, DEFAULT_REPRODUCTION_CONFIG } from './reproduction';
/**
* NEAT Evolution Engine
*
* Coordinates the entire evolution process:
* - Population management
* - Speciation
* - Fitness evaluation
* - Reproduction
*/
export interface EvolutionConfig {
populationSize: number;
inputCount: number;
outputCount: number;
compatibilityConfig: CompatibilityConfig;
reproductionConfig: ReproductionConfig;
}
export const DEFAULT_EVOLUTION_CONFIG: EvolutionConfig = {
populationSize: 40,
inputCount: 53, // Ray sensors + extra inputs
outputCount: 5, // moveX, moveY, turn, shoot, reserved
compatibilityConfig: DEFAULT_COMPATIBILITY_CONFIG,
reproductionConfig: DEFAULT_REPRODUCTION_CONFIG,
};
export interface Population {
genomes: Genome[];
species: Species[];
generation: number;
compatibilityThreshold: number;
innovationTracker: InnovationTracker;
bestGenomeEver: Genome | null;
bestFitnessEver: number;
}
/**
* Create initial population
*/
export function createPopulation(config: EvolutionConfig): Population {
const innovationTracker = new InnovationTracker();
const genomes: Genome[] = [];
for (let i = 0; i < config.populationSize; i++) {
genomes.push(createMinimalGenome(
config.inputCount,
config.outputCount,
innovationTracker
));
}
return {
genomes,
species: [],
generation: 0,
compatibilityThreshold: 1.5, // Balanced to target 6-10 species
innovationTracker,
bestGenomeEver: null,
bestFitnessEver: -Infinity,
};
}
/**
* Evolve the population by one generation
*
* Note: This assumes genomes have already been evaluated and have fitness values.
*/
export function evolveGeneration(population: Population, config: EvolutionConfig): Population {
// 1. Speciate
const species = speciate(
population.genomes,
population.species,
population.compatibilityThreshold,
config.compatibilityConfig
);
// 2. Apply fitness sharing
applyFitnessSharing(species);
// 3. Remove stagnant species (optional for now)
// TODO: Implement staleness checking and removal
// 4. Track best genome
let bestGenome = population.bestGenomeEver;
let bestFitness = population.bestFitnessEver;
for (const genome of population.genomes) {
if (genome.fitness > bestFitness) {
bestFitness = genome.fitness;
bestGenome = genome;
}
}
// 5. Reproduce
const newGenomes = reproduce(
species,
config.populationSize,
population.innovationTracker,
config.reproductionConfig
);
// 6. Adjust compatibility threshold
const newThreshold = adjustCompatibilityThreshold(
population.compatibilityThreshold,
species.length
);
return {
genomes: newGenomes,
species,
generation: population.generation + 1,
compatibilityThreshold: newThreshold,
innovationTracker: population.innovationTracker,
bestGenomeEver: bestGenome,
bestFitnessEver: bestFitness,
};
}
/**
* Get statistics for the current population
*/
export function getPopulationStats(population: Population) {
const fitnesses = population.genomes.map(g => g.fitness);
const avgFitness = fitnesses.reduce((a, b) => a + b, 0) / fitnesses.length;
const maxFitness = Math.max(...fitnesses);
const minFitness = Math.min(...fitnesses);
// When population comes from worker, innovationTracker is a plain object
// Access the private property directly instead of calling method
const totalInnovations = (population.innovationTracker as any).currentInnovation || 0;
return {
generation: population.generation,
speciesCount: population.species.length,
avgFitness,
maxFitness,
minFitness,
bestFitnessEver: population.bestFitnessEver,
totalInnovations,
};
}

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import type { Genome } from './genome';
import type { EvolutionConfig } from './evolution';
/**
* Export/Import system for trained genomes.
*
* Allows saving champion genomes as JSON files and loading them back
* for exhibition matches or continued training.
*/
export interface ExportedGenome {
version: string;
timestamp: number;
config: {
inputCount: number;
outputCount: number;
};
genome: Genome;
metadata?: {
generation?: number;
fitness?: number;
speciesCount?: number;
};
}
const EXPORT_VERSION = '1.0.0';
/**
* Export a genome to a downloadable JSON format
*/
export function exportGenome(
genome: Genome,
config: EvolutionConfig,
metadata?: ExportedGenome['metadata']
): ExportedGenome {
return {
version: EXPORT_VERSION,
timestamp: Date.now(),
config: {
inputCount: config.inputCount,
outputCount: config.outputCount,
},
genome: {
nodes: genome.nodes,
connections: genome.connections,
fitness: genome.fitness,
},
metadata,
};
}
/**
* Import a genome from JSON
*/
export function importGenome(exported: ExportedGenome): {
genome: Genome;
config: { inputCount: number; outputCount: number };
} {
// Version check
if (exported.version !== EXPORT_VERSION) {
console.warn(`Imported genome version ${exported.version} may be incompatible with current version ${EXPORT_VERSION}`);
}
return {
genome: exported.genome,
config: exported.config,
};
}
/**
* Download genome as JSON file
*/
export function downloadGenomeAsFile(exported: ExportedGenome, filename?: string): void {
const json = JSON.stringify(exported, null, 2);
const blob = new Blob([json], { type: 'application/json' });
const url = URL.createObjectURL(blob);
const link = document.createElement('a');
link.href = url;
link.download = filename || `neat-champion-${Date.now()}.json`;
document.body.appendChild(link);
link.click();
document.body.removeChild(link);
URL.revokeObjectURL(url);
}
/**
* Upload and parse genome from file
*/
export function uploadGenomeFromFile(): Promise<ExportedGenome> {
return new Promise((resolve, reject) => {
const input = document.createElement('input');
input.type = 'file';
input.accept = 'application/json,.json';
input.onchange = (e) => {
const file = (e.target as HTMLInputElement).files?.[0];
if (!file) {
reject(new Error('No file selected'));
return;
}
const reader = new FileReader();
reader.onload = (event) => {
try {
const json = event.target?.result as string;
const exported = JSON.parse(json) as ExportedGenome;
resolve(exported);
} catch (err) {
reject(new Error('Failed to parse genome file'));
}
};
reader.onerror = () => reject(new Error('Failed to read file'));
reader.readAsText(file);
};
input.click();
});
}

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import type { SimulationState } from './types';
import { hasLineOfSight } from './sensors';
/**
* Fitness calculation for NEAT Arena.
*
* Fitness rewards:
* - +10 per hit on opponent
* - -10 per being hit
* - -0.002 per tick (time penalty to encourage aggression)
* - -0.2 per shot fired (ammo management)
* - +0.01 per tick when aiming well at visible opponent
*/
export interface FitnessTracker {
agentId: number;
fitness: number;
// For incremental calculation
lastKills: number;
lastHits: number;
shotsFired: number;
}
/**
* Create a new fitness tracker
*/
export function createFitnessTracker(agentId: number): FitnessTracker {
return {
agentId,
fitness: 0,
lastKills: 0,
lastHits: 0,
shotsFired: 0,
};
}
/**
* Update fitness based on current simulation state
*/
export function updateFitness(tracker: FitnessTracker, state: SimulationState): FitnessTracker {
const agent = state.agents.find(a => a.id === tracker.agentId)!;
const opponent = state.agents.find(a => a.id !== tracker.agentId)!;
const newTracker = { ...tracker };
// Reward for new kills
const newKills = agent.kills - tracker.lastKills;
newTracker.fitness += newKills * 10;
newTracker.lastKills = agent.kills;
// Penalty for being hit
const newHits = agent.hits - tracker.lastHits;
newTracker.fitness -= newHits * 10;
newTracker.lastHits = agent.hits;
// Time penalty (encourages finishing quickly)
newTracker.fitness -= 0.002;
// Check if agent fired this tick (cooldown just set)
if (agent.fireCooldown === 10) {
newTracker.shotsFired++;
newTracker.fitness -= 0.2;
}
// Reward for aiming at visible opponent
if (hasLineOfSight(agent, opponent, state.map.walls)) {
const dx = opponent.position.x - agent.position.x;
const dy = opponent.position.y - agent.position.y;
const angleToOpponent = Math.atan2(dy, dx);
// Normalize angle difference
let angleDiff = angleToOpponent - agent.aimAngle;
while (angleDiff > Math.PI) angleDiff -= 2 * Math.PI;
while (angleDiff < -Math.PI) angleDiff += 2 * Math.PI;
const cosAngleDiff = Math.cos(angleDiff);
// Reward if aiming close (cos > 0.95 ≈ within ~18°)
if (cosAngleDiff > 0.95) {
newTracker.fitness += 0.01;
}
}
return newTracker;
}

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src/lib/neatArena/genome.ts Normal file
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/**
* NEAT Genome Implementation
*
* Represents a neural network genome with node genes and connection genes.
* Implements the core NEAT genome structure as described in the original paper.
*/
export type NodeType = 'input' | 'hidden' | 'output';
export type ActivationFunction = 'tanh' | 'sigmoid' | 'relu' | 'linear';
/**
* Node gene - represents a neuron
*/
export interface NodeGene {
id: number;
type: NodeType;
activation: ActivationFunction;
}
/**
* Connection gene - represents a synapse
*/
export interface ConnectionGene {
innovation: number;
from: number;
to: number;
weight: number;
enabled: boolean;
}
/**
* Complete genome
*/
export interface Genome {
nodes: NodeGene[];
connections: ConnectionGene[];
fitness: number;
}
/**
* Global innovation tracker for historical markings
*/
export class InnovationTracker {
private currentInnovation: number = 0;
private innovationHistory: Map<string, number> = new Map();
/**
* Get or create innovation number for a connection
*/
getInnovation(from: number, to: number): number {
const key = `${from}->${to}`;
if (this.innovationHistory.has(key)) {
return this.innovationHistory.get(key)!;
}
const innovation = this.currentInnovation++;
this.innovationHistory.set(key, innovation);
return innovation;
}
/**
* Reset innovation tracking (useful for new experiments)
*/
reset(): void {
this.currentInnovation = 0;
this.innovationHistory.clear();
}
/**
* Get current innovation count
*/
getCurrentInnovation(): number {
return this.currentInnovation;
}
}
/**
* Create a minimal genome with only input and output nodes, fully connected
*/
export function createMinimalGenome(
inputCount: number,
outputCount: number,
innovationTracker: InnovationTracker
): Genome {
const nodes: NodeGene[] = [];
const connections: ConnectionGene[] = [];
// Create input nodes (IDs 0 to inputCount-1)
for (let i = 0; i < inputCount; i++) {
nodes.push({
id: i,
type: 'input',
activation: 'linear',
});
}
// Create output nodes (IDs starting from inputCount)
for (let i = 0; i < outputCount; i++) {
nodes.push({
id: inputCount + i,
type: 'output',
activation: 'tanh',
});
}
// Create fully connected minimal genome
for (let i = 0; i < inputCount; i++) {
const inputNode = i; // Assuming inputNode refers to the ID
for (let o = 0; o < outputCount; o++) {
const outputNode = inputCount + o; // Assuming outputNode refers to the ID
const innovation = innovationTracker.getInnovation(inputNode, outputNode);
connections.push({
innovation,
from: inputNode,
to: outputNode,
weight: (Math.random() * 4) - 2, // Random weight in [-2, 2] for initial diversity
enabled: true,
});
}
}
return {
nodes,
connections,
fitness: 0,
};
}
/**
* Clone a genome (deep copy)
*/
export function cloneGenome(genome: Genome): Genome {
return {
nodes: genome.nodes.map(n => ({ ...n })),
connections: genome.connections.map(c => ({ ...c })),
fitness: genome.fitness,
};
}
/**
* Get next available node ID
*/
export function getNextNodeId(genome: Genome): number {
return Math.max(...genome.nodes.map(n => n.id)) + 1;
}
/**
* Check if a connection already exists
*/
export function connectionExists(genome: Genome, from: number, to: number): boolean {
return genome.connections.some(c => c.from === from && c.to === to);
}
/**
* Check if adding a connection would create a cycle (for feedforward networks)
*/
export function wouldCreateCycle(genome: Genome, from: number, to: number): boolean {
// Build adjacency list
const adj = new Map<number, number[]>();
for (const node of genome.nodes) {
adj.set(node.id, []);
}
for (const conn of genome.connections) {
if (!conn.enabled) continue;
if (!adj.has(conn.from)) adj.set(conn.from, []);
adj.get(conn.from)!.push(conn.to);
}
// Add the proposed connection
if (!adj.has(from)) adj.set(from, []);
adj.get(from)!.push(to);
// DFS to detect cycle
const visited = new Set<number>();
const recStack = new Set<number>();
const hasCycle = (nodeId: number): boolean => {
visited.add(nodeId);
recStack.add(nodeId);
const neighbors = adj.get(nodeId) || [];
for (const neighbor of neighbors) {
if (!visited.has(neighbor)) {
if (hasCycle(neighbor)) return true;
} else if (recStack.has(neighbor)) {
return true;
}
}
recStack.delete(nodeId);
return false;
};
// Check from the 'from' node
return hasCycle(from);
}
/**
* Serialize genome to JSON
*/
export function serializeGenome(genome: Genome): string {
return JSON.stringify(genome, null, 2);
}
/**
* Deserialize genome from JSON
*/
export function deserializeGenome(json: string): Genome {
return JSON.parse(json);
}

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import type { ArenaMap, Wall, SpawnPoint, AABB, Vec2 } from './types';
import { SIMULATION_CONFIG } from './types';
import { SeededRandom } from './utils';
/**
* Generates a symmetric arena map with procedurally placed walls.
*
* The map is generated by creating walls on the left half, then mirroring them
* to the right half for perfect symmetry.
*
* Spawn points are placed symmetrically as well.
*/
export function generateArenaMap(seed: number): ArenaMap {
const rng = new SeededRandom(seed);
const { WORLD_SIZE } = SIMULATION_CONFIG;
const walls: Wall[] = [];
const spawnPoints: SpawnPoint[] = [];
// Add boundary walls
const wallThickness = 16;
walls.push(
// Top
{ rect: { minX: 0, minY: 0, maxX: WORLD_SIZE, maxY: wallThickness } },
// Bottom
{ rect: { minX: 0, minY: WORLD_SIZE - wallThickness, maxX: WORLD_SIZE, maxY: WORLD_SIZE } },
// Left
{ rect: { minX: 0, minY: 0, maxX: wallThickness, maxY: WORLD_SIZE } },
// Right
{ rect: { minX: WORLD_SIZE - wallThickness, minY: 0, maxX: WORLD_SIZE, maxY: WORLD_SIZE } }
);
// Generate interior walls on left half, then mirror
const numInteriorWalls = rng.nextInt(3, 6);
const leftHalfWalls: AABB[] = [];
for (let i = 0; i < numInteriorWalls; i++) {
const width = rng.nextFloat(30, 80);
const height = rng.nextFloat(30, 80);
// Keep walls in left half (with margin)
const minX = rng.nextFloat(wallThickness + 20, WORLD_SIZE / 2 - width - 20);
const minY = rng.nextFloat(wallThickness + 20, WORLD_SIZE - height - wallThickness - 20);
const wall: AABB = {
minX,
minY,
maxX: minX + width,
maxY: minY + height,
};
leftHalfWalls.push(wall);
walls.push({ rect: wall });
}
// Mirror walls to right half
for (const leftWall of leftHalfWalls) {
const centerX = WORLD_SIZE / 2;
const distFromCenter = centerX - ((leftWall.minX + leftWall.maxX) / 2);
const mirroredCenterX = centerX + distFromCenter;
const wallWidth = leftWall.maxX - leftWall.minX;
const mirroredWall: AABB = {
minX: mirroredCenterX - wallWidth / 2,
maxX: mirroredCenterX + wallWidth / 2,
minY: leftWall.minY,
maxY: leftWall.maxY,
};
walls.push({ rect: mirroredWall });
}
// Generate 5 symmetric spawn point pairs
// Spawn points should be clear of walls
for (let pairId = 0; pairId < 5; pairId++) {
let leftSpawn: Vec2;
let attempts = 0;
// Find a valid spawn point on the left
do {
leftSpawn = {
x: rng.nextFloat(wallThickness + 40, WORLD_SIZE / 2 - 40),
y: rng.nextFloat(wallThickness + 40, WORLD_SIZE - wallThickness - 40),
};
attempts++;
} while (isPositionInWall(leftSpawn, walls) && attempts < 50);
// Mirror to right
const rightSpawn: Vec2 = {
x: WORLD_SIZE - leftSpawn.x,
y: leftSpawn.y,
};
spawnPoints.push(
{ position: leftSpawn, pairId, side: 0 },
{ position: rightSpawn, pairId, side: 1 }
);
}
return {
walls,
spawnPoints,
seed,
};
}
/**
* Check if a position overlaps with any wall
*/
function isPositionInWall(pos: Vec2, walls: Wall[]): boolean {
const margin = 20; // give some breathing room
for (const wall of walls) {
if (
pos.x >= wall.rect.minX - margin &&
pos.x <= wall.rect.maxX + margin &&
pos.y >= wall.rect.minY - margin &&
pos.y <= wall.rect.maxY + margin
) {
return true;
}
}
return false;
}

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import type { Genome, InnovationTracker } from './genome';
import {
cloneGenome,
getNextNodeId,
connectionExists,
wouldCreateCycle,
} from './genome';
/**
* NEAT Mutations
*
* Implements the core mutation operations:
* - Weight perturbation (80%)
* - Weight reset (10%)
* - Add connection (5%)
* - Add node (3%)
* - Toggle connection (2%)
*/
export interface MutationRates {
mutateWeightsProb: number;
resetWeightProb: number;
addConnectionProb: number;
addNodeProb: number;
toggleConnectionProb: number;
perturbationPower: number;
resetRange: number;
}
/**
* Default mutation probabilities
*/
export const DEFAULT_MUTATION_RATES: MutationRates = {
mutateWeightsProb: 0.50, // Reduced from 0.8 to allow more structural mutations
resetWeightProb: 0.05, // Reduced from 0.1
addConnectionProb: 0.20, // Increased from 0.05 for more diversity
addNodeProb: 0.15, // Increased from 0.03 for more complexity
toggleConnectionProb: 0.10, // Increased from 0.02
// Weight mutation parameters
perturbationPower: 0.5, // Increased from 0.1 for stronger weight changes
resetRange: 2.0, // Weight reset range
};
/**
* Apply mutations to a genome
*/
export function mutate(genome: Genome, tracker: InnovationTracker, rates = DEFAULT_MUTATION_RATES): void {
let addedConnections = 0;
let addedNodes = 0;
let toggledConnections = 0;
// Mutate weights
if (Math.random() < rates.mutateWeightsProb) {
mutateWeights(genome, rates);
}
// Reset a random weight
if (Math.random() < rates.resetWeightProb) {
resetWeight(genome, rates);
}
// Add connection
if (Math.random() < rates.addConnectionProb) {
if (addConnection(genome, tracker)) {
addedConnections++;
}
}
// Add node
if (Math.random() < rates.addNodeProb) {
if (addNode(genome, tracker)) {
addedNodes++;
}
}
// Toggle connection
if (Math.random() < rates.toggleConnectionProb) {
if (toggleConnection(genome)) {
toggledConnections++;
}
}
// Log structural mutations (only if any happened)
if (addedConnections > 0 || addedNodes > 0 || toggledConnections > 0) {
console.log(`[Mutation] +${addedConnections} conn, +${addedNodes} nodes, ${toggledConnections} toggled`);
}
}
/**
* Perturb weights slightly
*/
function mutateWeights(genome: Genome, rates: MutationRates): void {
for (const conn of genome.connections) {
if (Math.random() < 0.9) {
// Small perturbation
conn.weight += (Math.random() * 2 - 1) * rates.perturbationPower;
// Clamp to reasonable range
conn.weight = Math.max(-5, Math.min(5, conn.weight));
}
}
}
/**
* Reset a random weight to a new random value
*/
function resetWeight(genome: Genome, rates: MutationRates): void {
if (genome.connections.length === 0) return;
const conn = genome.connections[Math.floor(Math.random() * genome.connections.length)];
conn.weight = (Math.random() * 2 - 1) * rates.resetRange;
}
/**
* Add a new connection between two nodes
*/
function addConnection(genome: Genome, innovationTracker: InnovationTracker): boolean {
const inputNodes = genome.nodes.filter(n => n.type === 'input');
const nonInputNodes = genome.nodes.filter(n => n.type !== 'input');
if (inputNodes.length === 0 || nonInputNodes.length === 0) return false;
// Try to find a valid connection
let attempts = 0;
const maxAttempts = 20;
while (attempts < maxAttempts) {
// Random from node (any node)
const fromNode = genome.nodes[Math.floor(Math.random() * genome.nodes.length)];
// Random to node (not input)
const toNode = nonInputNodes[Math.floor(Math.random() * nonInputNodes.length)];
// Can't connect to itself
if (fromNode.id === toNode.id) {
attempts++;
continue;
}
// Check if connection already exists
if (connectionExists(genome, fromNode.id, toNode.id)) {
attempts++;
continue;
}
// Check if it would create a cycle
if (wouldCreateCycle(genome, fromNode.id, toNode.id)) {
attempts++;
continue;
}
// Valid connection!
genome.connections.push({
innovation: innovationTracker.getInnovation(fromNode.id, toNode.id),
from: fromNode.id,
to: toNode.id,
weight: (Math.random() * 2 - 1) * 2, // [-2, 2]
enabled: true,
});
return true;
}
return false;
}
/**
* Add a new node by splitting an existing connection
*/
function addNode(genome: Genome, innovationTracker: InnovationTracker): boolean {
const enabledConnections = genome.connections.filter(c => c.enabled);
if (enabledConnections.length === 0) return false;
// Pick a random enabled connection
const conn = enabledConnections[Math.floor(Math.random() * enabledConnections.length)];
// Disable the old connection
conn.enabled = false;
// Create new node
const newNodeId = getNextNodeId(genome);
genome.nodes.push({
id: newNodeId,
type: 'hidden',
activation: 'tanh',
});
// Create two new connections:
// 1. from -> newNode (weight = 1.0)
genome.connections.push({
innovation: innovationTracker.getInnovation(conn.from, newNodeId),
from: conn.from,
to: newNodeId,
weight: 1.0,
enabled: true,
});
// 2. newNode -> to (weight = old connection's weight)
genome.connections.push({
innovation: innovationTracker.getInnovation(newNodeId, conn.to),
from: newNodeId,
to: conn.to,
weight: conn.weight,
enabled: true,
});
return true;
}
/**
* Toggle a random connection's enabled state
*/
function toggleConnection(genome: Genome): boolean {
if (genome.connections.length === 0) return false;
const conn = genome.connections[Math.floor(Math.random() * genome.connections.length)];
conn.enabled = !conn.enabled;
return true;
}

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import type { Genome, NodeGene, ConnectionGene, ActivationFunction } from './genome';
/**
* Feedforward neural network built from a NEAT genome.
*
* The network is built by topologically sorting the nodes and
* evaluating them in order to ensure feedforward behavior.
*/
interface NetworkNode {
id: number;
activation: ActivationFunction;
inputs: { weight: number; sourceId: number }[];
value: number;
}
export class NeuralNetwork {
private inputNodes: number[];
private outputNodes: number[];
private nodes: Map<number, NetworkNode>;
private evaluationOrder: number[];
constructor(genome: Genome) {
this.inputNodes = [];
this.outputNodes = [];
this.nodes = new Map();
this.evaluationOrder = [];
this.buildNetwork(genome);
}
/**
* Build the network from the genome
*/
private buildNetwork(genome: Genome): void {
// Create network nodes
for (const nodeGene of genome.nodes) {
this.nodes.set(nodeGene.id, {
id: nodeGene.id,
activation: nodeGene.activation,
inputs: [],
value: 0,
});
if (nodeGene.type === 'input') {
this.inputNodes.push(nodeGene.id);
} else if (nodeGene.type === 'output') {
this.outputNodes.push(nodeGene.id);
}
}
// Add connections
for (const conn of genome.connections) {
if (!conn.enabled) continue;
const targetNode = this.nodes.get(conn.to);
if (targetNode) {
targetNode.inputs.push({
weight: conn.weight,
sourceId: conn.from,
});
}
}
// Compute evaluation order (topological sort)
this.evaluationOrder = this.topologicalSort(genome);
}
/**
* Topological sort to determine evaluation order
*/
private topologicalSort(genome: Genome): number[] {
const inDegree = new Map<number, number>();
const adj = new Map<number, number[]>();
// Initialize
for (const node of genome.nodes) {
inDegree.set(node.id, 0);
adj.set(node.id, []);
}
// Build adjacency list and in-degrees
for (const conn of genome.connections) {
if (!conn.enabled) continue;
adj.get(conn.from)!.push(conn.to);
inDegree.set(conn.to, (inDegree.get(conn.to) || 0) + 1);
}
// Kahn's algorithm
const queue: number[] = [];
const order: number[] = [];
// Start with nodes that have no incoming edges
for (const [nodeId, degree] of inDegree.entries()) {
if (degree === 0) {
queue.push(nodeId);
}
}
while (queue.length > 0) {
const nodeId = queue.shift()!;
order.push(nodeId);
for (const neighbor of adj.get(nodeId) || []) {
inDegree.set(neighbor, inDegree.get(neighbor)! - 1);
if (inDegree.get(neighbor) === 0) {
queue.push(neighbor);
}
}
}
return order;
}
/**
* Activate the network with inputs and return outputs
*/
activate(inputs: number[]): number[] {
if (inputs.length !== this.inputNodes.length) {
throw new Error(`Expected ${this.inputNodes.length} inputs, got ${inputs.length}`);
}
// Reset all node values
for (const node of this.nodes.values()) {
node.value = 0;
}
// Set input values
for (let i = 0; i < this.inputNodes.length; i++) {
const node = this.nodes.get(this.inputNodes[i])!;
node.value = inputs[i];
}
// Evaluate nodes in topological order
for (const nodeId of this.evaluationOrder) {
const node = this.nodes.get(nodeId)!;
// Skip input nodes (already set)
if (this.inputNodes.includes(nodeId)) continue;
// Sum weighted inputs
let sum = 0;
for (const input of node.inputs) {
const sourceNode = this.nodes.get(input.sourceId);
if (sourceNode) {
sum += sourceNode.value * input.weight;
}
}
// Apply activation function
node.value = this.applyActivation(sum, node.activation);
}
// Collect output values
return this.outputNodes.map(id => this.nodes.get(id)!.value);
}
/**
* Apply activation function
*/
private applyActivation(x: number, activation: ActivationFunction): number {
switch (activation) {
case 'tanh':
return Math.tanh(x);
case 'sigmoid':
return 1 / (1 + Math.exp(-x));
case 'relu':
return Math.max(0, x);
case 'linear':
return x;
default:
return Math.tanh(x);
}
}
}
/**
* Create a neural network from a genome
*/
export function createNetwork(genome: Genome): NeuralNetwork {
return new NeuralNetwork(genome);
}

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import type { Genome, InnovationTracker } from './genome';
import type { Species } from './speciation';
import { cloneGenome } from './genome';
import { crossover } from './crossover';
import { mutate, DEFAULT_MUTATION_RATES, type MutationRates } from './mutations';
/**
* NEAT Reproduction
*
* Handles species-based selection, crossover, and offspring generation.
* Implements elitism and proper offspring allocation.
*/
export interface ReproductionConfig {
elitePerSpecies: number;
crossoverRate: number;
interspeciesMatingRate: number;
mutationRates: MutationRates;
}
export const DEFAULT_REPRODUCTION_CONFIG: ReproductionConfig = {
elitePerSpecies: 1,
crossoverRate: 0.75,
interspeciesMatingRate: 0.001,
mutationRates: DEFAULT_MUTATION_RATES,
};
/**
* Reproduce a new generation from species
*/
export function reproduce(
species: Species[],
populationSize: number,
innovationTracker: InnovationTracker,
config: ReproductionConfig = DEFAULT_REPRODUCTION_CONFIG
): Genome[] {
const newGenomes: Genome[] = [];
// Calculate total adjusted fitness
const totalAdjustedFitness = species.reduce((sum, s) => {
return sum + s.members.reduce((sSum, g) => sSum + g.fitness, 0);
}, 0);
if (totalAdjustedFitness === 0) {
// If all fitness is 0, allocate equally
const genomesPerSpecies = Math.floor(populationSize / species.length);
for (const spec of species) {
const offspring = reproduceSpecies(
spec,
genomesPerSpecies,
innovationTracker,
config
);
newGenomes.push(...offspring);
}
} else {
// Allocate offspring based on adjusted fitness
for (const spec of species) {
const speciesFitness = spec.members.reduce((sum, g) => sum + g.fitness, 0);
const offspringCount = Math.max(
1,
Math.floor((speciesFitness / totalAdjustedFitness) * populationSize)
);
const offspring = reproduceSpecies(
spec,
offspringCount,
innovationTracker,
config
);
newGenomes.push(...offspring);
}
}
// If we don't have enough genomes, fill with random mutations of best
while (newGenomes.length < populationSize) {
const bestGenome = getBestGenomeFromSpecies(species);
const mutated = mutate(bestGenome, innovationTracker, config.mutationRates);
newGenomes.push(mutated);
}
// If we have too many, trim the worst
if (newGenomes.length > populationSize) {
newGenomes.sort((a, b) => b.fitness - a.fitness);
newGenomes.length = populationSize;
}
return newGenomes;
}
/**
* Reproduce offspring within a species
*/
function reproduceSpecies(
species: Species,
offspringCount: number,
innovationTracker: InnovationTracker,
config: ReproductionConfig
): Genome[] {
const offspring: Genome[] = [];
// Sort members by fitness
const sorted = [...species.members].sort((a, b) => b.fitness - a.fitness);
// Elitism: keep best genomes unchanged
const eliteCount = Math.min(config.elitePerSpecies, sorted.length, offspringCount);
for (let i = 0; i < eliteCount; i++) {
offspring.push(cloneGenome(sorted[i]));
}
// Generate rest through crossover and mutation
while (offspring.length < offspringCount) {
let child: Genome;
// Select parents
const parent1 = selectParent(sorted);
const parent2 = sorted.length >= 2 ? selectParent(sorted) : null;
// Crossover if we have two different parents, otherwise clone
if (parent2 && parent1 !== parent2 && Math.random() < config.crossoverRate) {
child = crossover(parent1, parent2, innovationTracker);
} else {
child = cloneGenome(parent1);
}
// Always mutate (except elites)
mutate(child, innovationTracker, config.mutationRates);
offspring.push(child);
}
return offspring;
}
/**
* Select a parent using fitness-proportionate selection
*/
function selectParent(sortedGenomes: Genome[]): Genome {
// Simple tournament selection (top 50%)
const tournamentSize = Math.max(2, Math.floor(sortedGenomes.length * 0.5));
const index = Math.floor(Math.random() * tournamentSize);
return sortedGenomes[index];
}
/**
* Get the best genome from all species
*/
function getBestGenomeFromSpecies(species: Species[]): Genome {
let best: Genome | null = null;
for (const spec of species) {
for (const genome of spec.members) {
if (!best || genome.fitness > best.fitness) {
best = genome;
}
}
}
return best || species[0].members[0];
}

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import type { Genome } from './genome';
import type { Population } from './evolution';
import type { AgentAction } from './types';
import { createSimulation, stepSimulation } from './simulation';
import { createNetwork } from './network';
import { generateObservation, observationToInputs } from './sensors';
import { createFitnessTracker, updateFitness } from './fitness';
import { SeededRandom } from './utils';
/**
* Self-Play Scheduler
*
* Orchestrates training matches between genomes.
* Each genome plays K opponents, with side swapping for fairness.
*/
export interface MatchConfig {
matchesPerGenome: number; // K
mapSeed: number;
maxTicks: number;
}
export const DEFAULT_MATCH_CONFIG: MatchConfig = {
matchesPerGenome: 4,
mapSeed: 12345,
maxTicks: 600,
};
interface MatchPairing {
genome1Index: number;
genome2Index: number;
spawnPairId: number;
swapSides: boolean;
}
/**
* Evaluate entire population using self-play
*/
export function evaluatePopulation(
population: Population,
config: MatchConfig = DEFAULT_MATCH_CONFIG
): Population {
const genomes = population.genomes;
const K = config.matchesPerGenome;
// Initialize fitness trackers
const fitnessTrackers = genomes.map((_, i) => ({
totalFitness: 0,
matchCount: 0,
}));
// Generate deterministic pairings
const pairings = generatePairings(genomes.length, K, population.generation);
// Run all matches
for (const pairing of pairings) {
const result = runMatch(
genomes[pairing.genome1Index],
genomes[pairing.genome2Index],
pairing,
config
);
// Accumulate fitness
fitnessTrackers[pairing.genome1Index].totalFitness += result.fitness1;
fitnessTrackers[pairing.genome1Index].matchCount++;
fitnessTrackers[pairing.genome2Index].totalFitness += result.fitness2;
fitnessTrackers[pairing.genome2Index].matchCount++;
}
console.log('[SelfPlay] Ran', pairings.length, 'matches for', genomes.length, 'genomes');
console.log('[SelfPlay] Sample fitness from first genome:', fitnessTrackers[0].totalFitness, '/', fitnessTrackers[0].matchCount);
// Average fitness across matches
for (let i = 0; i < genomes.length; i++) {
const tracker = fitnessTrackers[i];
genomes[i].fitness = tracker.matchCount > 0
? tracker.totalFitness / tracker.matchCount
: 0;
}
return { ...population, genomes };
}
/**
* Generate deterministic match pairings
*/
function generatePairings(
populationSize: number,
K: number,
seed: number
): MatchPairing[] {
const pairings: MatchPairing[] = [];
const rng = new SeededRandom(seed);
for (let i = 0; i < populationSize; i++) {
for (let k = 0; k < K; k++) {
// Pick a random opponent (not self)
let opponentIndex;
do {
opponentIndex = rng.nextInt(0, populationSize);
} while (opponentIndex === i);
// Random spawn pair (0-4)
const spawnPairId = rng.nextInt(0, 5);
// Each match is played twice with swapped sides
pairings.push({
genome1Index: i,
genome2Index: opponentIndex,
spawnPairId,
swapSides: false,
});
pairings.push({
genome1Index: i,
genome2Index: opponentIndex,
spawnPairId,
swapSides: true,
});
}
}
return pairings;
}
/**
* Run a single match between two genomes
*/
function runMatch(
genome1: Genome,
genome2: Genome,
pairing: MatchPairing,
config: MatchConfig
): { fitness1: number; fitness2: number } {
// Swap genomes if needed for side fairness
const g1 = pairing.swapSides ? genome2 : genome1;
const g2 = pairing.swapSides ? genome1 : genome2;
// Create networks
const network1 = createNetwork(g1);
const network2 = createNetwork(g2);
// Create simulation
let sim = createSimulation(config.mapSeed + pairing.spawnPairId, pairing.spawnPairId);
// Create fitness trackers
let tracker1 = createFitnessTracker(0);
let tracker2 = createFitnessTracker(1);
// Run simulation
while (!sim.isOver && sim.tick < config.maxTicks) {
// Get observations
const obs1 = generateObservation(0, sim);
const obs2 = generateObservation(1, sim);
// Get actions from networks
const inputs1 = observationToInputs(obs1);
const inputs2 = observationToInputs(obs2);
const outputs1 = network1.activate(inputs1);
const outputs2 = network2.activate(inputs2);
const action1: AgentAction = {
moveX: outputs1[0],
moveY: outputs1[1],
turn: outputs1[2],
shoot: outputs1[3],
};
const action2: AgentAction = {
moveX: outputs2[0],
moveY: outputs2[1],
turn: outputs2[2],
shoot: outputs2[3],
};
// Step simulation
sim = stepSimulation(sim, [action1, action2]);
// Update fitness
tracker1 = updateFitness(tracker1, sim);
tracker2 = updateFitness(tracker2, sim);
}
// Swap fitness back if sides were swapped
if (pairing.swapSides) {
return {
fitness1: tracker2.fitness,
fitness2: tracker1.fitness,
};
} else {
return {
fitness1: tracker1.fitness,
fitness2: tracker2.fitness,
};
}
}

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import type { Agent, SimulationState, Observation, RayHit, Vec2, Wall } from './types';
import { SIMULATION_CONFIG } from './types';
/**
* Sensor system for NEAT Arena.
*
* Agents perceive the world using 360° raycasting.
* Each ray detects distance and what it hit (nothing, wall, or opponent).
*/
/**
* Generate observation vector for an agent.
*
* Returns a complete observation including:
* - 24 rays (360°) with distance and hit type
* - Agent's velocity
* - Aim direction
* - Fire cooldown
*/
export function generateObservation(agentId: number, state: SimulationState): Observation {
const agent = state.agents.find(a => a.id === agentId)!;
const opponent = state.agents.find(a => a.id !== agentId)!;
const { RAY_COUNT, RAY_RANGE, FIRE_COOLDOWN, AGENT_MAX_SPEED } = SIMULATION_CONFIG;
// Cast rays in 360°
const rays: RayHit[] = [];
const angleStep = (2 * Math.PI) / RAY_COUNT;
for (let i = 0; i < RAY_COUNT; i++) {
const angle = i * angleStep;
const ray = castRay(agent.position, angle, RAY_RANGE, state.map.walls, opponent);
rays.push(ray);
}
// Normalize velocity
const vx = agent.velocity.x / AGENT_MAX_SPEED;
const vy = agent.velocity.y / AGENT_MAX_SPEED;
// Aim direction as sin/cos
const aimSin = Math.sin(agent.aimAngle);
const aimCos = Math.cos(agent.aimAngle);
// Normalize cooldown
const cooldown = agent.fireCooldown / FIRE_COOLDOWN;
return {
rays,
vx,
vy,
aimSin,
aimCos,
cooldown,
};
}
/**
* Cast a single ray from origin in a direction, up to maxDist.
*
* Returns the closest hit: either wall, opponent, or nothing.
*/
function castRay(
origin: Vec2,
angle: number,
maxDist: number,
walls: Wall[],
opponent: Agent
): RayHit {
const dir: Vec2 = {
x: Math.cos(angle),
y: Math.sin(angle),
};
const rayEnd: Vec2 = {
x: origin.x + dir.x * maxDist,
y: origin.y + dir.y * maxDist,
};
let closestDist = maxDist;
let hitType: 'nothing' | 'wall' | 'opponent' = 'nothing';
// Check wall intersections
for (const wall of walls) {
const dist = rayAABBIntersection(origin, rayEnd, wall.rect);
if (dist !== null && dist < closestDist) {
closestDist = dist;
hitType = 'wall';
}
}
// Check opponent intersection (treat as circle)
const opponentDist = rayCircleIntersection(origin, dir, maxDist, opponent.position, opponent.radius);
if (opponentDist !== null && opponentDist < closestDist) {
closestDist = opponentDist;
hitType = 'opponent';
}
return {
distance: closestDist / maxDist, // Normalize to [0, 1]
hitType,
};
}
/**
* Ray-AABB intersection.
* Returns distance to intersection, or null if no hit.
*/
function rayAABBIntersection(
origin: Vec2,
end: Vec2,
aabb: { minX: number; minY: number; maxX: number; maxY: number }
): number | null {
const dir: Vec2 = {
x: end.x - origin.x,
y: end.y - origin.y,
};
const len = Math.sqrt(dir.x * dir.x + dir.y * dir.y);
if (len === 0) return null;
dir.x /= len;
dir.y /= len;
// Slab method
const invDirX = dir.x === 0 ? Infinity : 1 / dir.x;
const invDirY = dir.y === 0 ? Infinity : 1 / dir.y;
const tx1 = (aabb.minX - origin.x) * invDirX;
const tx2 = (aabb.maxX - origin.x) * invDirX;
const ty1 = (aabb.minY - origin.y) * invDirY;
const ty2 = (aabb.maxY - origin.y) * invDirY;
const tmin = Math.max(Math.min(tx1, tx2), Math.min(ty1, ty2));
const tmax = Math.min(Math.max(tx1, tx2), Math.max(ty1, ty2));
if (tmax < 0 || tmin > tmax || tmin > len) return null;
return tmin >= 0 ? tmin : tmax;
}
/**
* Ray-circle intersection.
* Returns distance to intersection, or null if no hit.
*/
function rayCircleIntersection(
origin: Vec2,
dir: Vec2,
maxDist: number,
circleCenter: Vec2,
circleRadius: number
): number | null {
// Vector from ray origin to circle center
const oc: Vec2 = {
x: origin.x - circleCenter.x,
y: origin.y - circleCenter.y,
};
const a = dir.x * dir.x + dir.y * dir.y;
const b = 2 * (oc.x * dir.x + oc.y * dir.y);
const c = oc.x * oc.x + oc.y * oc.y - circleRadius * circleRadius;
const discriminant = b * b - 4 * a * c;
if (discriminant < 0) return null;
const sqrtDisc = Math.sqrt(discriminant);
const t1 = (-b - sqrtDisc) / (2 * a);
const t2 = (-b + sqrtDisc) / (2 * a);
// Return closest positive intersection within range
if (t1 >= 0 && t1 <= maxDist) return t1;
if (t2 >= 0 && t2 <= maxDist) return t2;
return null;
}
/**
* Convert observation to flat array of floats for neural network input.
*
* Total: 24 rays × 2 + 5 extra = 53 inputs
*/
export function observationToInputs(obs: Observation): number[] {
const inputs: number[] = [];
// Rays: distance + hitType as scalar
for (const ray of obs.rays) {
inputs.push(ray.distance);
// Encode hitType as scalar
let hitTypeScalar = 0;
if (ray.hitType === 'wall') hitTypeScalar = 0.5;
else if (ray.hitType === 'opponent') hitTypeScalar = 1.0;
inputs.push(hitTypeScalar);
}
// Extra inputs
inputs.push(obs.vx);
inputs.push(obs.vy);
inputs.push(obs.aimSin);
inputs.push(obs.aimCos);
inputs.push(obs.cooldown);
return inputs;
}
/**
* Check if agent has clear line-of-sight to opponent.
* Used for fitness calculation.
*/
export function hasLineOfSight(agent: Agent, opponent: Agent, walls: Wall[]): boolean {
const dir: Vec2 = {
x: opponent.position.x - agent.position.x,
y: opponent.position.y - agent.position.y,
};
const dist = Math.sqrt(dir.x * dir.x + dir.y * dir.y);
if (dist === 0) return true;
dir.x /= dist;
dir.y /= dist;
// Check if any wall blocks the line
for (const wall of walls) {
const hitDist = rayAABBIntersection(agent.position, opponent.position, wall.rect);
if (hitDist !== null && hitDist < dist) {
return false;
}
}
return true;
}

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import type {
SimulationState,
Agent,
Bullet,
AgentAction,
Vec2,
Wall,
MatchResult,
} from './types';
import { SIMULATION_CONFIG } from './types';
import { generateArenaMap } from './mapGenerator';
/**
* Core simulation engine for the NEAT Arena.
*
* Deterministic, operates at fixed 30Hz timestep.
* Handles agent movement, bullet physics, collisions, respawning, and scoring.
*/
let nextBulletId = 0;
/**
* Create a new simulation instance
*/
export function createSimulation(mapSeed: number, spawnPairId: number): SimulationState {
const map = generateArenaMap(mapSeed);
// Get spawn points for the selected pair
const spawns = map.spawnPoints.filter(sp => sp.pairId === spawnPairId);
const spawn0 = spawns.find(sp => sp.side === 0)!.position;
const spawn1 = spawns.find(sp => sp.side === 1)!.position;
const agents: [Agent, Agent] = [
createAgent(0, spawn0),
createAgent(1, spawn1),
];
return {
tick: 0,
agents,
bullets: [],
map,
isOver: false,
};
}
/**
* Create a new agent
*/
function createAgent(id: number, spawnPoint: Vec2): Agent {
return {
id,
position: { x: spawnPoint.x, y: spawnPoint.y },
velocity: { x: 0, y: 0 },
aimAngle: id === 0 ? 0 : Math.PI, // Face each other initially
radius: SIMULATION_CONFIG.AGENT_RADIUS,
invulnTicks: SIMULATION_CONFIG.RESPAWN_INVULN_TICKS,
fireCooldown: 0,
hits: 0,
kills: 0,
spawnPoint,
};
}
/**
* Step the simulation forward by one tick
*/
export function stepSimulation(
state: SimulationState,
actions: [AgentAction, AgentAction]
): SimulationState {
if (state.isOver) return state;
const newState = { ...state };
newState.tick++;
// Update agents
newState.agents = [
updateAgent(state.agents[0], actions[0], state),
updateAgent(state.agents[1], actions[1], state),
];
// Update bullets
newState.bullets = state.bullets
.map(b => updateBullet(b, state))
.filter(b => b !== null) as Bullet[];
// Check bullet-agent collisions
checkCollisions(newState);
// Check episode termination
if (newState.tick >= SIMULATION_CONFIG.MAX_TICKS) {
newState.isOver = true;
newState.result = createMatchResult(newState);
} else if (newState.agents[0].kills >= SIMULATION_CONFIG.KILLS_TO_WIN ||
newState.agents[1].kills >= SIMULATION_CONFIG.KILLS_TO_WIN) {
newState.isOver = true;
newState.result = createMatchResult(newState);
}
return newState;
}
/**
* Update a single agent
*/
function updateAgent(agent: Agent, action: AgentAction, state: SimulationState): Agent {
const { DT, AGENT_MAX_SPEED, AGENT_TURN_RATE, FIRE_COOLDOWN, BULLET_SPAWN_OFFSET, BULLET_SPEED } = SIMULATION_CONFIG;
const newAgent = { ...agent };
// Decrease timers
if (newAgent.invulnTicks > 0) newAgent.invulnTicks--;
if (newAgent.fireCooldown > 0) newAgent.fireCooldown--;
// Update aim angle
const turnAmount = action.turn * AGENT_TURN_RATE * DT;
newAgent.aimAngle += turnAmount;
// Normalize angle to [-π, π]
newAgent.aimAngle = ((newAgent.aimAngle + Math.PI) % (2 * Math.PI)) - Math.PI;
// Update velocity
const moveLength = Math.sqrt(action.moveX * action.moveX + action.moveY * action.moveY);
if (moveLength > 0) {
newAgent.velocity.x = (action.moveX / moveLength) * AGENT_MAX_SPEED;
newAgent.velocity.y = (action.moveY / moveLength) * AGENT_MAX_SPEED;
} else {
newAgent.velocity.x = 0;
newAgent.velocity.y = 0;
}
// Update position
let newX = newAgent.position.x + newAgent.velocity.x * DT;
let newY = newAgent.position.y + newAgent.velocity.y * DT;
// Check wall collisions and clamp position
const testPos = { x: newX, y: newY };
if (isAgentCollidingWithWalls(testPos, newAgent.radius, state.map.walls)) {
// Simple response: stop movement
newX = newAgent.position.x;
newY = newAgent.position.y;
newAgent.velocity.x = 0;
newAgent.velocity.y = 0;
}
newAgent.position.x = newX;
newAgent.position.y = newY;
// Fire bullet
if (action.shoot > 0.5 && newAgent.fireCooldown === 0) {
newAgent.fireCooldown = FIRE_COOLDOWN;
// Spawn bullet in front of agent
const bulletPos: Vec2 = {
x: newAgent.position.x + Math.cos(newAgent.aimAngle) * BULLET_SPAWN_OFFSET,
y: newAgent.position.y + Math.sin(newAgent.aimAngle) * BULLET_SPAWN_OFFSET,
};
const bullet: Bullet = {
id: nextBulletId++,
position: bulletPos,
velocity: {
x: Math.cos(newAgent.aimAngle) * BULLET_SPEED,
y: Math.sin(newAgent.aimAngle) * BULLET_SPEED,
},
ownerId: newAgent.id,
ttl: SIMULATION_CONFIG.BULLET_TTL,
};
state.bullets.push(bullet);
}
return newAgent;
}
/**
* Update a bullet
*/
function updateBullet(bullet: Bullet, state: SimulationState): Bullet | null {
const { DT } = SIMULATION_CONFIG;
const newBullet = { ...bullet };
newBullet.ttl--;
if (newBullet.ttl <= 0) return null;
// Update position
newBullet.position.x += newBullet.velocity.x * DT;
newBullet.position.y += newBullet.velocity.y * DT;
// Check wall collision
if (isBulletCollidingWithWalls(newBullet.position, state.map.walls)) {
return null; // Bullet destroyed
}
return newBullet;
}
/**
* Check for bullet-agent collisions and handle hits
*/
function checkCollisions(state: SimulationState): void {
const bulletsToRemove = new Set<number>();
for (const bullet of state.bullets) {
for (const agent of state.agents) {
// Can't hit yourself or invulnerable agents
if (bullet.ownerId === agent.id || agent.invulnTicks > 0) continue;
const dx = bullet.position.x - agent.position.x;
const dy = bullet.position.y - agent.position.y;
const distSq = dx * dx + dy * dy;
if (distSq < agent.radius * agent.radius) {
// Hit!
bulletsToRemove.add(bullet.id);
// Update scores
agent.hits++;
const shooter = state.agents.find(a => a.id === bullet.ownerId);
if (shooter) shooter.kills++;
// Respawn agent
agent.position.x = agent.spawnPoint.x;
agent.position.y = agent.spawnPoint.y;
agent.velocity.x = 0;
agent.velocity.y = 0;
agent.invulnTicks = SIMULATION_CONFIG.RESPAWN_INVULN_TICKS;
}
}
}
// Remove bullets
state.bullets = state.bullets.filter(b => !bulletsToRemove.has(b.id));
}
/**
* Check if an agent collides with any walls
*/
function isAgentCollidingWithWalls(pos: Vec2, radius: number, walls: Wall[]): boolean {
for (const wall of walls) {
// AABB vs circle collision
const closestX = Math.max(wall.rect.minX, Math.min(pos.x, wall.rect.maxX));
const closestY = Math.max(wall.rect.minY, Math.min(pos.y, wall.rect.maxY));
const dx = pos.x - closestX;
const dy = pos.y - closestY;
const distSq = dx * dx + dy * dy;
if (distSq < radius * radius) {
return true;
}
}
return false;
}
/**
* Check if a bullet collides with any walls
*/
function isBulletCollidingWithWalls(pos: Vec2, walls: Wall[]): boolean {
for (const wall of walls) {
if (pos.x >= wall.rect.minX && pos.x <= wall.rect.maxX &&
pos.y >= wall.rect.minY && pos.y <= wall.rect.maxY) {
return true;
}
}
return false;
}
/**
* Create match result
*/
function createMatchResult(state: SimulationState): MatchResult {
const [a0, a1] = state.agents;
let winnerId = -1;
if (a0.kills > a1.kills) winnerId = 0;
else if (a1.kills > a0.kills) winnerId = 1;
return {
winnerId,
scores: [a0.kills, a1.kills],
ticks: state.tick,
};
}

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import type { Genome } from './genome';
/**
* NEAT Speciation
*
* Groups genomes into species based on compatibility distance.
* Implements dynamic threshold adjustment to target 6-10 species.
*/
export interface Species {
id: number;
representative: Genome;
members: Genome[];
averageFitness: number;
staleness: number; // Generations without improvement
}
/**
* Compatibility distance coefficients
*/
export interface CompatibilityConfig {
excessCoeff: number; // c1
disjointCoeff: number; // c2
weightDiffCoeff: number; // c3
}
export const DEFAULT_COMPATIBILITY_CONFIG: CompatibilityConfig = {
excessCoeff: 1.0,
disjointCoeff: 1.0,
weightDiffCoeff: 0.4,
};
/**
* Calculate compatibility distance between two genomes
* δ = c1*E/N + c2*D/N + c3*W
*/
export function compatibilityDistance(
genome1: Genome,
genome2: Genome,
config: CompatibilityConfig = DEFAULT_COMPATIBILITY_CONFIG
): number {
const innovations1 = new Set(genome1.connections.map(c => c.innovation));
const innovations2 = new Set(genome2.connections.map(c => c.innovation));
const max1 = Math.max(...Array.from(innovations1), 0);
const max2 = Math.max(...Array.from(innovations2), 0);
const maxInnovation = Math.max(max1, max2);
let matching = 0;
let disjoint = 0;
let excess = 0;
let weightDiff = 0;
const conn1Map = new Map(genome1.connections.map(c => [c.innovation, c]));
const conn2Map = new Map(genome2.connections.map(c => [c.innovation, c]));
// Count matching, disjoint, excess
const allInnovations = new Set([...innovations1, ...innovations2]);
for (const innovation of allInnovations) {
const c1 = conn1Map.get(innovation);
const c2 = conn2Map.get(innovation);
if (c1 && c2) {
// Matching gene
matching++;
weightDiff += Math.abs(c1.weight - c2.weight);
} else {
// Disjoint or excess
// Excess genes are those with innovation > OTHER genome's max
const isInGenome1 = innovations1.has(innovation);
const isInGenome2 = innovations2.has(innovation);
if (isInGenome1 && innovation > max2) {
excess++;
} else if (isInGenome2 && innovation > max1) {
excess++;
} else {
disjoint++;
}
}
}
// Normalize by number of genes in larger genome
const N = Math.max(genome1.connections.length, genome2.connections.length, 1);
// Average weight difference for matching genes
const avgWeightDiff = matching > 0 ? weightDiff / matching : 0;
const delta =
(config.excessCoeff * excess) / N +
(config.disjointCoeff * disjoint) / N +
config.weightDiffCoeff * avgWeightDiff;
return delta;
}
/**
* Assign genomes to species
*/
export function speciate(
genomes: Genome[],
previousSpecies: Species[],
compatibilityThreshold: number,
config: CompatibilityConfig = DEFAULT_COMPATIBILITY_CONFIG
): Species[] {
const newSpecies: Species[] = [];
let nextSpeciesId = previousSpecies.length > 0
? Math.max(...previousSpecies.map(s => s.id)) + 1
: 0;
// Update representatives from previous generation
for (const species of previousSpecies) {
if (species.members.length > 0) {
// Pick a random member as the new representative
species.representative = species.members[Math.floor(Math.random() * species.members.length)];
species.members = [];
}
}
// Assign each genome to a species
for (const genome of genomes) {
let foundSpecies = false;
// Try to match with existing species
for (const species of previousSpecies) {
const distance = compatibilityDistance(genome, species.representative, config);
if (distance < compatibilityThreshold) {
species.members.push(genome);
foundSpecies = true;
break;
}
}
// If no match, create new species
if (!foundSpecies) {
const newSpec: Species = {
id: nextSpeciesId++,
representative: genome,
members: [genome],
averageFitness: 0,
staleness: 0,
};
previousSpecies.push(newSpec);
}
}
// Keep only species with members
for (const species of previousSpecies) {
if (species.members.length > 0) {
// Calculate average fitness
const totalFitness = species.members.reduce((sum, g) => sum + g.fitness, 0);
species.averageFitness = totalFitness / species.members.length;
newSpecies.push(species);
}
}
console.log(`[Speciation] Threshold: ${compatibilityThreshold.toFixed(2)}, Species formed: ${newSpecies.length}`);
if (newSpecies.length > 0) {
console.log(`[Speciation] Species sizes:`, newSpecies.map(s => s.members.length));
}
return newSpecies;
}
/**
* Adjust compatibility threshold to target a certain number of species
*/
export function adjustCompatibilityThreshold(
currentThreshold: number,
currentSpeciesCount: number,
targetMin: number = 6,
targetMax: number = 10
): number {
const adjustmentRate = 0.1;
if (currentSpeciesCount < targetMin) {
// Too few species, make threshold more lenient
return currentThreshold + adjustmentRate;
} else if (currentSpeciesCount > targetMax) {
// Too many species, make threshold stricter
return Math.max(0.1, currentThreshold - adjustmentRate);
}
return currentThreshold;
}
/**
* Apply fitness sharing within species
*/
export function applyFitnessSharing(species: Species[]): void {
for (const spec of species) {
const speciesSize = spec.members.length;
for (const genome of spec.members) {
// Adjusted fitness = raw fitness / species size
genome.fitness = genome.fitness / speciesSize;
}
}
}

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import type { Population } from './evolution';
import type { EvolutionConfig } from './evolution';
import { evaluatePopulation, DEFAULT_MATCH_CONFIG } from './selfPlay';
import { evolveGeneration, createPopulation, getPopulationStats } from './evolution';
/**
* NEAT Training Worker
*
* Runs training in a background thread to prevent UI blocking.
* The main thread only handles visualization and UI updates.
*/
export interface TrainingWorkerMessage {
type: 'start' | 'pause' | 'step' | 'reset' | 'init';
config?: EvolutionConfig;
}
export interface TrainingWorkerResponse {
type: 'update' | 'error' | 'ready';
population?: Population;
stats?: ReturnType<typeof getPopulationStats>;
error?: string;
}
let population: Population | null = null;
let isRunning = false;
let config: EvolutionConfig | null = null;
/**
* Handle messages from main thread
*/
self.onmessage = async (e: MessageEvent<TrainingWorkerMessage>) => {
const message = e.data;
try {
switch (message.type) {
case 'init':
if (message.config) {
config = message.config;
population = createPopulation(config);
sendUpdate();
self.postMessage({ type: 'ready' } as TrainingWorkerResponse);
}
break;
case 'start':
isRunning = true;
runTrainingLoop();
break;
case 'pause':
isRunning = false;
break;
case 'step':
if (population && config) {
const stats = await runSingleGeneration();
sendUpdate(stats);
}
break;
case 'reset':
if (config) {
population = createPopulation(config);
isRunning = false;
sendUpdate();
}
break;
}
} catch (error) {
self.postMessage({
type: 'error',
error: error instanceof Error ? error.message : 'Unknown error',
} as TrainingWorkerResponse);
}
};
/**
* Run continuous training loop
*/
async function runTrainingLoop() {
while (isRunning && population && config) {
const stats = await runSingleGeneration();
sendUpdate(stats);
// Yield to allow pause/stop messages to be processed
await new Promise(resolve => setTimeout(resolve, 0));
}
}
/**
* Run a single generation
*/
async function runSingleGeneration(): Promise<ReturnType<typeof getPopulationStats> | null> {
if (!population || !config) return null;
console.log('[Worker] Starting generation', population.generation);
// Evaluate population
const evaluatedPop = evaluatePopulation(population, DEFAULT_MATCH_CONFIG);
// Check fitness after evaluation
const fitnesses = evaluatedPop.genomes.map(g => g.fitness);
const avgFit = fitnesses.reduce((a, b) => a + b, 0) / fitnesses.length;
const maxFit = Math.max(...fitnesses);
console.log('[Worker] After evaluation - Avg fitness:', avgFit.toFixed(2), 'Max:', maxFit.toFixed(2));
// Evolve to next generation
population = evolveGeneration(evaluatedPop, config);
console.log('[Worker] Generation', population.generation, 'complete');
// IMPORTANT: Send stats from the EVALUATED population, not the evolved one
// (evolved population has fitness reset to 0)
return getPopulationStats(evaluatedPop);
}
/**
* Send population update to main thread
*/
function sendUpdate(stats?: ReturnType<typeof getPopulationStats> | null) {
if (!population) return;
self.postMessage({
type: 'update',
population,
stats: stats || undefined,
} as TrainingWorkerResponse);
}

204
src/lib/neatArena/types.ts Normal file
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/**
* Core types for the NEAT Arena simulation.
*
* The simulation is deterministic and operates at a fixed 30Hz timestep.
* All units are in a 512×512 logic space.
*/
// ============================================================================
// WORLD & MAP
// ============================================================================
export interface Vec2 {
x: number;
y: number;
}
export interface AABB {
minX: number;
minY: number;
maxX: number;
maxY: number;
}
export interface Wall {
rect: AABB;
}
export interface SpawnPoint {
position: Vec2;
/** Which spawn pair this belongs to (0-4) */
pairId: number;
/** Which side of the pair (0 or 1) */
side: 0 | 1;
}
export interface ArenaMap {
/** Rectangular walls */
walls: Wall[];
/** Symmetric spawn point pairs (always 5 pairs = 10 total spawn points) */
spawnPoints: SpawnPoint[];
/** Map generation seed */
seed: number;
}
// ============================================================================
// AGENT
// ============================================================================
export interface Agent {
id: number;
position: Vec2;
velocity: Vec2;
/** Current aim direction in radians */
aimAngle: number;
/** Radius for collision */
radius: number;
/** Invulnerability ticks remaining after respawn */
invulnTicks: number;
/** Cooldown ticks until can fire again */
fireCooldown: number;
/** Number of times hit this episode */
hits: number;
/** Number of times this agent landed a hit */
kills: number;
/** Assigned spawn point */
spawnPoint: Vec2;
}
// ============================================================================
// BULLET
// ============================================================================
export interface Bullet {
id: number;
position: Vec2;
velocity: Vec2;
/** Which agent fired this bullet */
ownerId: number;
/** Ticks until bullet auto-expires */
ttl: number;
}
// ============================================================================
// SIMULATION STATE
// ============================================================================
export interface SimulationState {
/** Current tick (increments at 30Hz) */
tick: number;
/** Agents in the arena (always 2) */
agents: [Agent, Agent];
/** Active bullets */
bullets: Bullet[];
/** The arena map */
map: ArenaMap;
/** Episode over? */
isOver: boolean;
/** Match result after episode ends */
result?: MatchResult;
}
export interface MatchResult {
/** Winner agent ID, or -1 for draw */
winnerId: number;
/** Final scores */
scores: [number, number];
/** Total ticks */
ticks: number;
}
// ============================================================================
// ACTIONS
// ============================================================================
export interface AgentAction {
/** Movement vector (will be normalized) */
moveX: number;
moveY: number;
/** Turn rate [-1..1] (scaled by max turn rate) */
turn: number;
/** Fire bullet if > 0.5 */
shoot: number;
}
// ============================================================================
// OBSERVATIONS / SENSORS
// ============================================================================
export interface RayHit {
/** Distance [0..1] normalized by max range */
distance: number;
/** What the ray hit */
hitType: 'nothing' | 'wall' | 'opponent';
}
export interface Observation {
/** 24 rays × 2 values (distance, hitType) */
rays: RayHit[];
/** Agent's own velocity */
vx: number;
vy: number;
/** Aim direction as unit vector */
aimSin: number;
aimCos: number;
/** Fire cooldown [0..1] */
cooldown: number;
}
// ============================================================================
// SIMULATION CONFIG
// ============================================================================
export const SIMULATION_CONFIG = {
/** Logic world size */
WORLD_SIZE: 512,
/** Fixed timestep (30Hz) */
TICK_RATE: 30,
DT: 1 / 30,
/** Episode termination */
MAX_TICKS: 600, // 20 seconds
KILLS_TO_WIN: 5,
/** Agent physics */
AGENT_RADIUS: 8,
AGENT_MAX_SPEED: 120, // units/sec
AGENT_TURN_RATE: 270 * (Math.PI / 180), // rad/sec
/** Respawn */
RESPAWN_INVULN_TICKS: 15, // 0.5 seconds
/** Bullet physics */
BULLET_SPEED: 260, // units/sec
BULLET_TTL: 60, // 2 seconds
FIRE_COOLDOWN: 10, // ~0.33 seconds
BULLET_SPAWN_OFFSET: 12, // spawn in front of agent
/** Sensors */
RAY_COUNT: 24,
RAY_RANGE: 220,
} as const;
// Re-export Genome type from genome module for convenience
export type { Genome } from './genome';

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/**
* Deterministic random number generator using a linear congruential generator (LCG).
*
* Ensures reproducible results for the same seed.
*/
export class SeededRandom {
private seed: number;
constructor(seed: number) {
this.seed = seed % 2147483647;
if (this.seed <= 0) this.seed += 2147483646;
}
/**
* Returns a float in [0, 1)
*/
next(): number {
this.seed = (this.seed * 16807) % 2147483647;
return (this.seed - 1) / 2147483646;
}
/**
* Returns an integer in [min, max) (max exclusive)
*/
nextInt(min: number, max: number): number {
return Math.floor(this.next() * (max - min)) + min;
}
/**
* Returns a float in [min, max)
*/
nextFloat(min: number, max: number): number {
return this.next() * (max - min) + min;
}
/**
* Returns a random boolean
*/
nextBool(): boolean {
return this.next() < 0.5;
}
}