draw busses

src/VehicleSystem.js

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+import * as THREE from 'three';
+
+export class VehicleSystem {
+  constructor(scene) {
+    this.scene = scene;
+    this.buses = []; // { mesh, points, dists, totalLen, currentDist, speed, direction }
+
+    this.busGeom = new THREE.BoxGeometry(3.5, 4.0, 10.0);
+    this.busGeom.translate(0, 3.5, 0);
+
+    this.busMat = new THREE.MeshStandardMaterial({
+      color: 0xF59E0B,      // Amber body
+      emissive: 0xB45309,   // Slight orange glow so they don't get lost in shadow
+      emissiveIntensity: 0.4,
+      roughness: 0.2
+    });
+  }
+
+  addBusToRoute(routePathPoints) {
+    if (!routePathPoints || routePathPoints.length < 2) return;
+
+    // Clone points to ensure they aren't affected by outside changes
+    const points = routePathPoints.map(p => p.clone());
+
+    const mesh = new THREE.Mesh(this.busGeom, this.busMat);
+    mesh.position.copy(points[0]);
+    mesh.castShadow = true;
+    this.scene.add(mesh);
+
+    // Pre-calculate cumulative distances for smooth interpolation
+    let totalLen = 0;
+    const dists = [0];
+    for (let i = 0; i < points.length - 1; i++) {
+      const d = points[i].distanceTo(points[i + 1]);
+      totalLen += d;
+      dists.push(totalLen);
+    }
+
+    this.buses.push({
+      mesh: mesh,
+      points: points,
+      dists: dists,
+      totalLen: totalLen,
+      currentDist: 0,
+      speed: 40, // Speed in units/sec
+      direction: 1 // 1 = Forward, -1 = Backward
+    });
+  }
+
+  update(deltaTime) {
+    this.buses.forEach(bus => {
+      // 1. Move
+      bus.currentDist += bus.speed * deltaTime * bus.direction;
+
+      // 2. Check Bounds & Reversal
+      if (bus.currentDist >= bus.totalLen) {
+        bus.currentDist = bus.totalLen;
+        bus.direction = -1;
+      } else if (bus.currentDist <= 0) {
+        bus.currentDist = 0;
+        bus.direction = 1;
+      }
+
+      // 3. Find current segment index
+      let i = 0;
+      // Simple linear search (efficient enough for small N points)
+      while (i < bus.dists.length - 2 && bus.currentDist > bus.dists[i + 1]) {
+        i++;
+      }
+
+      // 4. Interpolate Position
+      const startDist = bus.dists[i];
+      const endDist = bus.dists[i + 1];
+      const segmentLen = endDist - startDist;
+
+      // Avoid divide by zero if 2 points are identical
+      const alpha = segmentLen > 0.0001 ? (bus.currentDist - startDist) / segmentLen : 0;
+
+      const pStart = bus.points[i];
+      const pEnd = bus.points[i + 1];
+
+      bus.mesh.position.lerpVectors(pStart, pEnd, alpha);
+
+      // 5. Rotation (Look at target)
+      const lookTarget = bus.direction === 1 ? pEnd : pStart;
+      bus.mesh.lookAt(lookTarget);
+    });
+  }
+}