Pass Tile SSEs to ViewUpdateResult

CHANGES.md

@@ -9,6 +9,7 @@
 ##### Additions :tada:
 
 - Added a constructor overload for `Cesium3DTilesSelection::ITwinCesiumCuratedContentLoaderFactory` to override the iTwin Cesium Curated Content base URL. This makes it possible to connect to alternate servers (e.g., staging, QA, mock servers).
+- Added `ViewUpdateResult::tileScreenSpaceErrorThisFrame`, which stores the screen space errors computed for tiles in `tilesToRenderThisFrame`.
 
 ##### Fixes :wrench:
 

Cesium3DTilesSelection/include/Cesium3DTilesSelection/Tileset.h

@@ -522,10 +522,12 @@ class CESIUM3DTILESSELECTION_API Tileset final {
       const TilesetFrameState& frameState,
       Tile& tile,
       double tilePriority,
+      double tileSse,
       ViewUpdateResult& result);
   TraversalDetails _renderInnerTile(
       const TilesetFrameState& frameState,
       Tile& tile,
+      double tileSse,
       ViewUpdateResult& result);
   bool _kickDescendantsAndRenderTile(
       const TilesetFrameState& frameState,
@@ -535,7 +537,8 @@ class CESIUM3DTILESSELECTION_API Tileset final {
       size_t firstRenderedDescendantIndex,
       const TilesetViewGroup::LoadQueueCheckpoint& loadQueueBeforeChildren,
       bool queuedForLoad,
-      double tilePriority);
+      double tilePriority,
+      double tileSse);
   TileOcclusionState _checkOcclusion(const Tile& tile);
 
   TraversalDetails _visitTile(
@@ -545,6 +548,7 @@ class CESIUM3DTILESSELECTION_API Tileset final {
       bool ancestorMeetsSse,
       Tile& tile,
       double tilePriority,
+      double tileSse,
       ViewUpdateResult& result);
 
   struct CullResult {
@@ -564,11 +568,11 @@ class CESIUM3DTILESSELECTION_API Tileset final {
       const TilesetFrameState& frameState,
       const std::vector<double>& distances,
       CullResult& cullResult);
-  bool _meetsSse(
+  double _computeSse(
       const std::vector<ViewState>& frustums,
       const Tile& tile,
-      const std::vector<double>& distances,
-      bool culled) const noexcept;
+      const std::vector<double>& distances) const noexcept;
+  bool _meetsSseThreshold(double sse, bool culled) const noexcept;
 
   TraversalDetails _visitTileIfNeeded(
       const TilesetFrameState& frameState,
@@ -593,6 +597,7 @@ class CESIUM3DTILESSELECTION_API Tileset final {
    * @param result The current view update result.
    * @param tilePriority The load priority of this tile.
    * priority.
+   * @param tileSse The screen space error of this tile.
    * @param queuedForLoad True if this tile has already been queued for loading.
    * @return true The additive-refined tile was queued for load and added to the
    * render list.
@@ -603,6 +608,7 @@ class CESIUM3DTILESSELECTION_API Tileset final {
       Tile& tile,
       ViewUpdateResult& result,
       double tilePriority,
+      double tileSse,
       bool queuedForLoad);
 
   void _unloadCachedTiles(double timeBudget) noexcept;

Cesium3DTilesSelection/include/Cesium3DTilesSelection/ViewUpdateResult.h

@@ -24,17 +24,26 @@ class CESIUM3DTILESSELECTION_API ViewUpdateResult final {
    * @brief The tiles that were selected by the tileset traversal this frame.
    * These tiles should be rendered by the client.
    *
-   * Tiles in this list may be fading in if
-   * {@link TilesetOptions::enableLodTransitionPeriod} is true.
+   * Tiles in this list may be fading in if \ref
+   * TilesetOptions::enableLodTransitionPeriod is true.
    */
   std::vector<Tile::ConstPointer> tilesToRenderThisFrame;
 
+  /**
+   * @brief The computed screen space error of the tiles selected by the
+   * tileset traversal this frame. The values correspond to the tiles linked in
+   * \ref tilesToRenderThisFrame, and may be used by the client to influence
+   * rendering behavior.
+   */
+  std::vector<double> tileScreenSpaceErrorThisFrame;
+
   /**
    * @brief Tiles on this list are no longer selected for rendering.
    *
-   * If {@link TilesetOptions::enableLodTransitionPeriod} is true they may be
-   * fading out. If a tile's {TileRenderContent::lodTransitionPercentage} is 0
-   * or lod transitions are disabled, the tile should be hidden right away.
+   * If \ref TilesetOptions::enableLodTransitionPeriod is true they may be
+   * fading out. If a tile's \ref
+   * TileRenderContent::getLodTransitionFadePercentage is 0 or LOD transitions
+   * are disabled, the tile should be hidden right away.
    */
   std::unordered_set<Tile::ConstPointer> tilesFadingOut;
 

Cesium3DTilesSelection/src/Tileset.cpp

@@ -856,15 +856,14 @@ void computeDistances(
 
 } // namespace
 
-bool Tileset::_meetsSse(
+double Tileset::_computeSse(
     const std::vector<ViewState>& frustums,
     const Tile& tile,
-    const std::vector<double>& distances,
-    bool culled) const noexcept {
-
+    const std::vector<double>& distances) const noexcept {
   double largestSse = 0.0;
 
-  for (size_t i = 0; i < frustums.size() && i < distances.size(); ++i) {
+  CESIUM_ASSERT(frustums.size() == distances.size());
+  for (size_t i = 0; i < frustums.size(); ++i) {
     const ViewState& frustum = frustums[i];
     const double distance = distances[i];
 
@@ -875,12 +874,22 @@ bool Tileset::_meetsSse(
       largestSse = sse;
     }
   }
+  return largestSse;
+}
 
+bool Tileset::_meetsSseThreshold(double sse, bool culled) const noexcept {
   return culled ? !this->_options.enforceCulledScreenSpaceError ||
-                      largestSse < this->_options.culledScreenSpaceError
-                : largestSse < this->_options.maximumScreenSpaceError;
+                      sse < this->_options.culledScreenSpaceError
+                : sse < this->_options.maximumScreenSpaceError;
 }
 
+namespace {
+void addTileToRender(ViewUpdateResult& result, Tile& tile, double sse) {
+  result.tilesToRenderThisFrame.emplace_back(&tile);
+  result.tileScreenSpaceErrorThisFrame.emplace_back(sse);
+}
+} // namespace
+
 // Visits a tile for possible rendering. When we call this function with a tile:
 //   * It is not yet known whether the tile is visible.
 //   * Its parent tile does _not_ meet the SSE (unless ancestorMeetsSse=true,
@@ -987,8 +996,8 @@ Tileset::TraversalDetails Tileset::_visitTileIfNeeded(
     ++result.culledTilesVisited;
   }
 
-  bool meetsSse =
-      this->_meetsSse(frameState.frustums, tile, distances, cullResult.culled);
+  double tileSse = this->_computeSse(frameState.frustums, tile, distances);
+  bool meetsSse = this->_meetsSseThreshold(tileSse, cullResult.culled);
 
   TraversalDetails details = this->_visitTile(
       frameState,
@@ -997,6 +1006,7 @@ Tileset::TraversalDetails Tileset::_visitTileIfNeeded(
       ancestorMeetsSse,
       tile,
       tilePriority,
+      tileSse,
       result);
 
   traversalState.finishNode(&tile);
@@ -1012,10 +1022,11 @@ Tileset::TraversalDetails Tileset::_renderLeaf(
     const TilesetFrameState& frameState,
     Tile& tile,
     double tilePriority,
+    double tileSse,
     ViewUpdateResult& result) {
   frameState.viewGroup.getTraversalState().currentState() =
       TileSelectionState(TileSelectionState::Result::Rendered);
-  result.tilesToRenderThisFrame.emplace_back(&tile);
+  addTileToRender(result, tile, tileSse);
 
   addTileToLoadQueue(
       frameState,
@@ -1059,14 +1070,15 @@ bool mustContinueRefiningToDeeperTiles(
 Tileset::TraversalDetails Tileset::_renderInnerTile(
     const TilesetFrameState& frameState,
     Tile& tile,
+    double tileSse,
     ViewUpdateResult& result) {
   addCurrentTileDescendantsToTilesFadingOutIfPreviouslyRendered(
       frameState.viewGroup,
       tile,
       result);
   frameState.viewGroup.getTraversalState().currentState() =
       TileSelectionState(TileSelectionState::Result::Rendered);
-  result.tilesToRenderThisFrame.emplace_back(&tile);
+  addTileToRender(result, tile, tileSse);
 
   return Tileset::createTraversalDetailsForSingleTile(frameState, tile);
 }
@@ -1076,11 +1088,12 @@ bool Tileset::_loadAndRenderAdditiveRefinedTile(
     Tile& tile,
     ViewUpdateResult& result,
     double tilePriority,
+    double tileSse,
     bool queuedForLoad) {
   // If this tile uses additive refinement, we need to render this tile in
   // addition to its children.
   if (tile.getRefine() == TileRefine::Add) {
-    result.tilesToRenderThisFrame.emplace_back(&tile);
+    addTileToRender(result, tile, tileSse);
     if (!queuedForLoad)
       addTileToLoadQueue(
           frameState,
@@ -1101,7 +1114,8 @@ bool Tileset::_kickDescendantsAndRenderTile(
     size_t firstRenderedDescendantIndex,
     const TilesetViewGroup::LoadQueueCheckpoint& loadQueueBeforeChildren,
     bool queuedForLoad,
-    double tilePriority) {
+    double tilePriority,
+    double tileSse) {
   // Mark all visited descendants of this tile as kicked.
   TilesetViewGroup::TraversalState& traversalState =
       frameState.viewGroup.getTraversalState();
@@ -1130,14 +1144,20 @@ bool Tileset::_kickDescendantsAndRenderTile(
 
   // Remove all descendants from the render list and add this tile.
   std::vector<Tile::ConstPointer>& renderList = result.tilesToRenderThisFrame;
+  std::vector<double>& sseList = result.tileScreenSpaceErrorThisFrame;
   renderList.erase(
       renderList.begin() +
           static_cast<std::vector<Tile*>::iterator::difference_type>(
               firstRenderedDescendantIndex),
       renderList.end());
+  sseList.erase(
+      sseList.begin() +
+          static_cast<std::vector<double>::iterator::difference_type>(
+              firstRenderedDescendantIndex),
+      sseList.end());
 
   if (tile.getRefine() != Cesium3DTilesSelection::TileRefine::Add) {
-    renderList.emplace_back(&tile);
+    addTileToRender(result, tile, tileSse);
   }
 
   traversalState.currentState() =
@@ -1291,6 +1311,7 @@ Tileset::TraversalDetails Tileset::_visitTile(
                            // children!
     Tile& tile,
     double tilePriority,
+    double tileSse,
     ViewUpdateResult& result) {
   TilesetViewGroup::TraversalState& traversalState =
       frameState.viewGroup.getTraversalState();
@@ -1300,7 +1321,7 @@ Tileset::TraversalDetails Tileset::_visitTile(
 
   // If this is a leaf tile, just render it (it's already been deemed visible).
   if (isLeaf(tile)) {
-    return this->_renderLeaf(frameState, tile, tilePriority, result);
+    return this->_renderLeaf(frameState, tile, tilePriority, tileSse, result);
   }
 
   const bool unconditionallyRefine = tile.getUnconditionallyRefine();
@@ -1404,7 +1425,7 @@ Tileset::TraversalDetails Tileset::_visitTile(
             tilePriority);
       }
 
-      return this->_renderInnerTile(frameState, tile, result);
+      return this->_renderInnerTile(frameState, tile, tileSse, result);
     }
   }
 
@@ -1415,6 +1436,7 @@ Tileset::TraversalDetails Tileset::_visitTile(
                       tile,
                       result,
                       tilePriority,
+                      tileSse,
                       queuedForLoad) ||
                   queuedForLoad;
 
@@ -1468,7 +1490,8 @@ Tileset::TraversalDetails Tileset::_visitTile(
         firstRenderedDescendantIndex,
         loadQueueBeforeChildren,
         queuedForLoad,
-        tilePriority);
+        tilePriority,
+        tileSse);
   } else {
     if (tile.getRefine() != TileRefine::Add) {
       addCurrentTileToTilesFadingOutIfPreviouslyRendered(

Cesium3DTilesSelection/src/TilesetViewGroup.cpp

@@ -128,6 +128,7 @@ void TilesetViewGroup::startNewFrame(
   this->_updateResult.maxDepthVisited = 0;
 
   this->_updateResult.tilesToRenderThisFrame.clear();
+  this->_updateResult.tileScreenSpaceErrorThisFrame.clear();
 
   if (!tileset.getOptions().enableLodTransitionPeriod) {
     this->_updateResult.tilesFadingOut.clear();