Const-only getRootTile, const tileset traversal.

This is an experiment.

Author: kring

Cesium3DTilesSelection/include/Cesium3DTilesSelection/Tile.h

@@ -128,7 +128,7 @@ class CESIUM3DTILESSELECTION_API Tile final {
    * and it may also keep its content from unloading. See {@link addReference}
    * for details.
    */
-  using Pointer = CesiumUtility::IntrusivePointer<Tile>;
+  using Pointer = CesiumUtility::IntrusivePointer<const Tile>;
 
   /**
    * @brief Construct a tile with unknown content and a loader that is used to
@@ -582,7 +582,7 @@ class CESIUM3DTILESSELECTION_API Tile final {
    * added. This can help debug reference counts when compiled with
    * `CESIUM_DEBUG_TILE_UNLOADING`.
    */
-  void addReference(const char* reason = nullptr) noexcept;
+  void addReference(const char* reason = nullptr) const noexcept;
 
   /**
    * @brief Removes a reference from this tile. A live reference will keep this
@@ -606,7 +606,7 @@ class CESIUM3DTILESSELECTION_API Tile final {
    * removed. This can help debug reference counts when compiled with
    * `CESIUM_DEBUG_TILE_UNLOADING`.
    */
-  void releaseReference(const char* reason = nullptr) noexcept;
+  void releaseReference(const char* reason = nullptr) const noexcept;
 
   /**
    * @brief Gets the current number of references to this tile.
@@ -697,7 +697,7 @@ class CESIUM3DTILESSELECTION_API Tile final {
   // mapped raster overlay
   std::vector<RasterMappedTo3DTile> _rasterTiles;
 
-  int32_t _referenceCount;
+  mutable int32_t _referenceCount;
 
   friend class TilesetContentManager;
   friend class MockTilesetContentManagerTestFixture;

Cesium3DTilesSelection/include/Cesium3DTilesSelection/TileLoadRequester.h

@@ -64,7 +64,7 @@ class TileLoadRequester {
    *
    * @return The next tile to load in a worker thread.
    */
-  virtual Tile* getNextTileToLoadInWorkerThread() = 0;
+  virtual const Tile* getNextTileToLoadInWorkerThread() = 0;
 
   /**
    * @brief Determines if this requester has any more tiles that need to be
@@ -92,7 +92,7 @@ class TileLoadRequester {
    *
    * @return The next tile to load in the main thread.
    */
-  virtual Tile* getNextTileToLoadInMainThread() = 0;
+  virtual const Tile* getNextTileToLoadInMainThread() = 0;
 
   /**
    * @brief Unregister this requester with the {link Tileset} with which it is

Cesium3DTilesSelection/include/Cesium3DTilesSelection/Tileset.h

@@ -188,13 +188,6 @@ class CESIUM3DTILESSELECTION_API Tileset final {
     return this->_options.ellipsoid;
   }
 
-  /**
-   * @brief Gets the root tile of this tileset.
-   *
-   * This may be `nullptr` if there is currently no root tile.
-   */
-  Tile* getRootTile() noexcept;
-
   /** @copydoc Tileset::getRootTile() */
   const Tile* getRootTile() const noexcept;
 
@@ -515,16 +508,16 @@ class CESIUM3DTILESSELECTION_API Tileset final {
 
   TraversalDetails _renderLeaf(
       const TilesetFrameState& frameState,
-      Tile& tile,
+      const Tile& tile,
       double tilePriority,
       ViewUpdateResult& result);
   TraversalDetails _renderInnerTile(
       const TilesetFrameState& frameState,
-      Tile& tile,
+      const Tile& tile,
       ViewUpdateResult& result);
   bool _kickDescendantsAndRenderTile(
       const TilesetFrameState& frameState,
-      Tile& tile,
+      const Tile& tile,
       ViewUpdateResult& result,
       TraversalDetails& traversalDetails,
       size_t firstRenderedDescendantIndex,
@@ -538,7 +531,7 @@ class CESIUM3DTILESSELECTION_API Tileset final {
       uint32_t depth,
       bool meetsSse,
       bool ancestorMeetsSse,
-      Tile& tile,
+      const Tile& tile,
       double tilePriority,
       ViewUpdateResult& result);
 
@@ -569,13 +562,13 @@ class CESIUM3DTILESSELECTION_API Tileset final {
       const TilesetFrameState& frameState,
       uint32_t depth,
       bool ancestorMeetsSse,
-      Tile& tile,
+      const Tile& tile,
       ViewUpdateResult& result);
   TraversalDetails _visitVisibleChildrenNearToFar(
       const TilesetFrameState& frameState,
       uint32_t depth,
       bool ancestorMeetsSse,
-      Tile& tile,
+      const Tile& tile,
       ViewUpdateResult& result);
 
   /**
@@ -595,7 +588,7 @@ class CESIUM3DTILESSELECTION_API Tileset final {
    */
   bool _loadAndRenderAdditiveRefinedTile(
       const TilesetFrameState& frameState,
-      Tile& tile,
+      const Tile& tile,
       ViewUpdateResult& result,
       double tilePriority,
       bool queuedForLoad);
@@ -631,7 +624,7 @@ class CESIUM3DTILESSELECTION_API Tileset final {
 
   void addTileToLoadQueue(
       const TilesetFrameState& frameState,
-      Tile& tile,
+      const Tile& tile,
       TileLoadPriorityGroup priorityGroup,
       double priority);
 

Cesium3DTilesSelection/src/Tile.cpp

@@ -392,7 +392,7 @@ bool isContentReferenced(const Tile& tile) {
 
 } // namespace
 
-void Tile::addReference([[maybe_unused]] const char* reason) noexcept {
+void Tile::addReference([[maybe_unused]] const char* reason) const noexcept {
   ++this->_referenceCount;
 
 #ifdef CESIUM_DEBUG_TILE_UNLOADING
@@ -430,7 +430,8 @@ void Tile::addReference([[maybe_unused]] const char* reason) noexcept {
   }
 }
 
-void Tile::releaseReference([[maybe_unused]] const char* reason) noexcept {
+void Tile::releaseReference(
+    [[maybe_unused]] const char* reason) const noexcept {
   CESIUM_ASSERT(this->_referenceCount > 0);
   --this->_referenceCount;