Keep query tiles loaded until we're done with them.

Cesium3DTilesSelection/src/Tileset.cpp

@@ -377,6 +377,7 @@ Tileset::updateView(const std::vector<ViewState>& frustums, float deltaTime) {
   TilesetHeightRequest::processHeightRequests(
       *this->_pTilesetContentManager,
       this->_options,
+      this->_loadedTiles,
       this->_heightRequests,
       this->_heightQueryLoadQueue);
 

Cesium3DTilesSelection/src/TilesetHeightQuery.cpp

@@ -118,7 +118,10 @@ void TilesetHeightQuery::intersectVisibleTile(
 
 void TilesetHeightQuery::findCandidateTiles(
     Tile* pTile,
+    Tile::LoadedLinkedList& loadedTiles,
     std::vector<std::string>& warnings) {
+  // Make sure this tile is not unloaded until we're done with it.
+  loadedTiles.insertAtTail(*pTile);
 
   // If tile failed to load, this means we can't complete the intersection
   if (pTile->getState() == TileLoadState::Failed) {
@@ -169,14 +172,15 @@ void TilesetHeightQuery::findCandidateTiles(
         continue;
 
       // Child is a candidate, traverse it and its children
-      findCandidateTiles(&child, warnings);
+      findCandidateTiles(&child, loadedTiles, warnings);
     }
   }
 }
 
 /*static*/ void TilesetHeightRequest::processHeightRequests(
     TilesetContentManager& contentManager,
     const TilesetOptions& options,
+    Tile::LoadedLinkedList& loadedTiles,
     std::list<TilesetHeightRequest>& heightRequests,
     std::vector<Tile*>& heightQueryLoadQueue) {
   if (heightRequests.empty())
@@ -190,6 +194,7 @@ void TilesetHeightQuery::findCandidateTiles(
     if (!request.tryCompleteHeightRequest(
             contentManager,
             options,
+            loadedTiles,
             tilesNeedingLoading)) {
       ++it;
     } else {
@@ -207,14 +212,18 @@ void TilesetHeightQuery::findCandidateTiles(
 bool TilesetHeightRequest::tryCompleteHeightRequest(
     TilesetContentManager& contentManager,
     const TilesetOptions& options,
+    Tile::LoadedLinkedList& loadedTiles,
     std::set<Tile*>& tilesNeedingLoading) {
   bool tileStillNeedsLoading = false;
   std::vector<std::string> warnings;
   for (TilesetHeightQuery& query : this->queries) {
     if (query.candidateTiles.empty() && query.additiveCandidateTiles.empty()) {
       // Find the initial set of tiles whose bounding volume is intersected by
       // the query ray.
-      query.findCandidateTiles(contentManager.getRootTile(), warnings);
+      query.findCandidateTiles(
+          contentManager.getRootTile(),
+          loadedTiles,
+          warnings);
     } else {
       // Refine the current set of candidate tiles, in case further tiles from
       // implicit tiling, external tilesets, etc. having been loaded since last
@@ -227,8 +236,12 @@ bool TilesetHeightRequest::tryCompleteHeightRequest(
         TileLoadState loadState = pCandidate->getState();
         if (!pCandidate->getChildren().empty() &&
             loadState >= TileLoadState::ContentLoaded) {
-          query.findCandidateTiles(pCandidate, warnings);
+          query.findCandidateTiles(pCandidate, loadedTiles, warnings);
         } else {
+          // Make sure this tile stays loaded.
+          loadedTiles.insertAtTail(*pCandidate);
+
+          // Check again next frame to see if this tile has children.
           query.candidateTiles.emplace_back(pCandidate);
         }
       }

Cesium3DTilesSelection/src/TilesetHeightQuery.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <Cesium3DTilesSelection/Tile.h>
 #include <CesiumAsync/Future.h>
 #include <CesiumAsync/Promise.h>
 #include <CesiumGeometry/Ray.h>
@@ -13,7 +14,6 @@
 
 namespace Cesium3DTilesSelection {
 
-class Tile;
 class TilesetContentManager;
 struct TilesetOptions;
 struct SampleHeightResult;
@@ -90,10 +90,16 @@ class TilesetHeightQuery {
    * {@link TilesetHeightQuery::additiveCandidateTiles}.
    *
    * @param pTile The tile at which to start traversal.
+   * @param loadedTiles The linked list of loaded tiles, used to ensure that
+   * tiles loaded for height queries stay loaded long enough to complete the
+   * query and no longer.
    * @param outWarnings On return, any warnings that occurred during candidate
    * search.
    */
-  void findCandidateTiles(Tile* pTile, std::vector<std::string>& outWarnings);
+  void findCandidateTiles(
+      Tile* pTile,
+      Tile::LoadedLinkedList& loadedTiles,
+      std::vector<std::string>& outWarnings);
 };
 
 /**
@@ -117,6 +123,9 @@ struct TilesetHeightRequest {
    *
    * @param contentManager The content manager.
    * @param options Options associated with the tileset.
+   * @param loadedTiles The linked list of loaded tiles, used to ensure that
+   * tiles loaded for height queries stay loaded long enough to complete the
+   * query and no longer.
    * @param heightRequests The list of all height requests. Completed requests
    * will be removed from this list.
    * @param heightQueryLoadQueue Tiles that still need to be loaded before all
@@ -125,6 +134,7 @@ struct TilesetHeightRequest {
   static void processHeightRequests(
       TilesetContentManager& contentManager,
       const TilesetOptions& options,
+      Tile::LoadedLinkedList& loadedTiles,
       std::list<TilesetHeightRequest>& heightRequests,
       std::vector<Tile*>& heightQueryLoadQueue);
 
@@ -134,12 +144,16 @@ struct TilesetHeightRequest {
    *
    * @param contentManager The content manager.
    * @param options Options associated with the tileset.
+   * @param loadedTiles The linked list of loaded tiles, used to ensure that
+   * tiles loaded for height queries stay loaded long enough to complete the
+   * query and no longer.
    * @param tilesNeedingLoading Tiles that needs to be loaded before this height
    * request can complete.
    */
   bool tryCompleteHeightRequest(
       TilesetContentManager& contentManager,
       const TilesetOptions& options,
+      Tile::LoadedLinkedList& loadedTiles,
       std::set<Tile*>& tilesNeedingLoading);
 };