feat: track visible items

Author: agviegas

packages/fragments/src/FragmentsModels/src/model/fragments-model.ts

@@ -26,7 +26,7 @@ import { FragmentsConnection } from "../multithreading/fragments-connection";
 import { MeshManager } from "./mesh-manager";
 
 import { AlignmentsManager } from "./alignments-manager";
-import { DataMap, EditRequest } from "../../../Utils";
+import { DataMap, EditRequest, Event } from "../../../Utils";
 import { SetupManager } from "./setup-manager";
 import { BoxManager } from "./box-manager";
 import { CoordinatesManager } from "./coordinates-manager";
@@ -69,6 +69,20 @@ export class FragmentsModel {
    */
   readonly tiles = new DataMap<string | number, BIMMesh>();
 
+  /**
+   * Event triggered after a view update cycle finishes processing.
+   * Listeners receive this FragmentsModel instance, allowing queries
+   * like {@link getItemsByVisibility} to retrieve seen/unseen elements.
+   */
+  readonly onViewUpdated = new Event<FragmentsModel>();
+
+  /**
+   * A set of item IDs that are currently visible (i.e. have at least
+   * one tile rendered on screen). Updated automatically as tiles are
+   * created and deleted by the mesh manager.
+   */
+  readonly visibleItems = new Set<number>();
+
   /**
    * The object that represents the model in the Three.js scene.
    */
@@ -204,6 +218,8 @@ export class FragmentsModel {
    */
   async dispose() {
     this._isLoaded = false;
+    this.visibleItems.clear();
+    this.onViewUpdated.reset();
     await this._dataManager.dispose(
       this,
       this._meshManager,
@@ -887,6 +903,7 @@ export class FragmentsModel {
    */
   _finishProcessing() {
     this._isProcessing = false;
+    this.onViewUpdated.trigger(this);
   }
 
   _setDeltaModel(modelId: string) {

packages/fragments/src/FragmentsModels/src/model/mesh-manager.ts

@@ -80,8 +80,15 @@ export class MeshManager {
       if (request.objectClass === undefined) return;
       const tile = this.create(request);
       this.setTileData(tile, request);
+      const uniqueIds = this.extractUniqueItemIds(request.itemIds);
+      tile.userData.itemIds = uniqueIds;
+      this.trackVisibleItems(model, uniqueIds, true);
       model.tiles.set(tile.userData.tileId, tile);
     } else if (tileRequestClass === TileRequestClass.DELETE) {
+      const tile = model.tiles.get(tileId);
+      if (tile?.userData.itemIds) {
+        this.trackVisibleItems(model, tile.userData.itemIds, false);
+      }
       model.tiles.delete(tileId);
     } else if (tileRequestClass === TileRequestClass.UPDATE) {
       const tileObject = model.tiles.get(tileId);
@@ -91,6 +98,29 @@ export class MeshManager {
     }
   }
 
+  private extractUniqueItemIds(itemIds: any): Set<number> {
+    const unique = new Set<number>();
+    if (!itemIds) return unique;
+    for (let i = 0; i < itemIds.length; i++) {
+      unique.add(itemIds[i]);
+    }
+    return unique;
+  }
+
+  private trackVisibleItems(
+    model: FragmentsModel,
+    itemIds: Set<number>,
+    added: boolean,
+  ) {
+    for (const itemId of itemIds) {
+      if (added) {
+        model.visibleItems.add(itemId);
+      } else {
+        model.visibleItems.delete(itemId);
+      }
+    }
+  }
+
   private createMesh(request: any) {
     const { indices, positions, normals, itemIds, faceIds } = request;
     const geometry = new THREE.BufferGeometry();