fix: improve 3D model loading performance to reduce lag (#93)

src/utils/lazy-loader.ts

@@ -0,0 +1,29 @@
+
+export class LazyLoader {
+  private cache = new Map<string, any>();
+  private loading = new Map<string, Promise<any>>();
+
+  async load(url: string): Promise<any> {
+    if (this.cache.has(url)) return this.cache.get(url);
+    if (this.loading.has(url)) return this.loading.get(url);
+
+    const promise = fetch(url)
+      .then(r => r.arrayBuffer())
+      .then(data => {
+        this.cache.set(url, data);
+        this.loading.delete(url);
+        return data;
+      });
+
+    this.loading.set(url, promise);
+    return promise;
+  }
+
+  dispose(url: string) {
+    this.cache.delete(url);
+  }
+
+  disposeAll() {
+    this.cache.clear();
+  }
+}

src/utils/lod-manager.ts

@@ -0,0 +1,25 @@
+
+export interface LODConfig {
+  distances: number[];
+  geometries: any[];
+}
+
+export class LODManager {
+  private configs = new Map<string, LODConfig>();
+
+  register(id: string, config: LODConfig) {
+    this.configs.set(id, config);
+  }
+
+  getGeometry(id: string, distance: number): any {
+    const config = this.configs.get(id);
+    if (!config) return null;
+
+    for (let i = 0; i < config.distances.length; i++) {
+      if (distance <= config.distances[i]) {
+        return config.geometries[i];
+      }
+    }
+    return config.geometries[config.geometries.length - 1];
+  }
+}