the-nexus/modules/scene-setup.js

// === SCENE SETUP + LIGHTING + SHADOWS + STAR FIELD + CONSTELLATION LINES ===
import * as THREE from 'three';
import { NEXUS } from './constants.js';

// === SCENE SETUP ===
export const scene = new THREE.Scene();

export const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 2000);
camera.position.set(0, 6, 11);

export const raycaster = new THREE.Raycaster();
export const forwardVector = new THREE.Vector3();

// === LIGHTING ===
export const ambientLight = new THREE.AmbientLight(0x0a1428, 1.4);
scene.add(ambientLight);

export const overheadLight = new THREE.SpotLight(0x8899bb, 0.6, 80, Math.PI / 3.5, 0.5, 1.0);
overheadLight.position.set(0, 25, 0);
overheadLight.target.position.set(0, 0, 0);
overheadLight.castShadow = true;
overheadLight.shadow.mapSize.set(2048, 2048);
overheadLight.shadow.camera.near = 5;
overheadLight.shadow.camera.far = 60;
overheadLight.shadow.bias = -0.001;
scene.add(overheadLight);
scene.add(overheadLight.target);

export const renderer = new THREE.WebGLRenderer({ antialias: true, alpha: true });
renderer.setClearColor(0x000000, 0);
renderer.setPixelRatio(window.devicePixelRatio);
renderer.setSize(window.innerWidth, window.innerHeight);
// === SHADOW SYSTEM ===
renderer.shadowMap.enabled = true;
renderer.shadowMap.type = THREE.PCFSoftShadowMap;
document.body.appendChild(renderer.domElement);

// === STAR FIELD ===
const STAR_COUNT = 800;
const STAR_SPREAD = 400;
const CONSTELLATION_DISTANCE = 30;

const starPositions = [];
const starGeo = new THREE.BufferGeometry();
const posArray = new Float32Array(STAR_COUNT * 3);
const sizeArray = new Float32Array(STAR_COUNT);

for (let i = 0; i < STAR_COUNT; i++) {
  const x = (Math.random() - 0.5) * STAR_SPREAD;
  const y = (Math.random() - 0.5) * STAR_SPREAD;
  const z = (Math.random() - 0.5) * STAR_SPREAD;
  posArray[i * 3] = x;
  posArray[i * 3 + 1] = y;
  posArray[i * 3 + 2] = z;
  sizeArray[i] = Math.random() * 2.5 + 0.5;
  starPositions.push(new THREE.Vector3(x, y, z));
}

starGeo.setAttribute('position', new THREE.BufferAttribute(posArray, 3));
starGeo.setAttribute('size', new THREE.BufferAttribute(sizeArray, 1));

export const starMaterial = new THREE.PointsMaterial({
  color: NEXUS.colors.starCore,
  size: 0.6,
  sizeAttenuation: true,
  transparent: true,
  opacity: 0.9,
});

export const stars = new THREE.Points(starGeo, starMaterial);
scene.add(stars);

// Star pulse state
export const STAR_BASE_OPACITY = 0.3;
export const STAR_PEAK_OPACITY = 1.0;
export const STAR_PULSE_DECAY = 0.012;

// === CONSTELLATION LINES ===
function buildConstellationLines() {
  const linePositions = [];
  const MAX_CONNECTIONS_PER_STAR = 3;
  const connectionCount = new Array(STAR_COUNT).fill(0);

  for (let i = 0; i < STAR_COUNT; i++) {
    if (connectionCount[i] >= MAX_CONNECTIONS_PER_STAR) continue;

    const neighbors = [];
    for (let j = i + 1; j < STAR_COUNT; j++) {
      if (connectionCount[j] >= MAX_CONNECTIONS_PER_STAR) continue;
      const dist = starPositions[i].distanceTo(starPositions[j]);
      if (dist < CONSTELLATION_DISTANCE) {
        neighbors.push({ j, dist });
      }
    }

    neighbors.sort((a, b) => a.dist - b.dist);
    const toConnect = neighbors.slice(0, MAX_CONNECTIONS_PER_STAR - connectionCount[i]);

    for (const { j } of toConnect) {
      linePositions.push(
        starPositions[i].x, starPositions[i].y, starPositions[i].z,
        starPositions[j].x, starPositions[j].y, starPositions[j].z
      );
      connectionCount[i]++;
      connectionCount[j]++;
    }
  }

  const lineGeo = new THREE.BufferGeometry();
  lineGeo.setAttribute('position', new THREE.BufferAttribute(new Float32Array(linePositions), 3));

  const lineMat = new THREE.LineBasicMaterial({
    color: NEXUS.colors.constellationLine,
    transparent: true,
    opacity: 0.18,
  });

  return new THREE.LineSegments(lineGeo, lineMat);
}

export const constellationLines = buildConstellationLines();
scene.add(constellationLines);