implement support for updating the render items of models when they finish their fade

libraries/entities-renderer/src/RenderableModelEntityItem.cpp

@@ -371,6 +371,12 @@ void RenderableModelEntityItem::render(RenderArgs* args) {
     PerformanceTimer perfTimer("RMEIrender");
     assert(getType() == EntityTypes::Model);
 
+    // When the individual mesh parts of a model finish fading, they will mark their Model as needing updating
+    // we will watch for that and ask the model to update it's render items
+    if (_model && _model->getRenderItemsNeedUpdate()) {
+        _model->updateRenderItems();
+    }
+
     if (hasModel()) {
         // Prepare the current frame
         {

libraries/render-utils/src/MeshPartPayload.cpp

@@ -526,6 +526,13 @@ void ModelMeshPartPayload::render(RenderArgs* args) const {
         return; // bail asap
     }
 
+    // When an individual mesh parts like this finishes its fade, we will mark the Model as 
+    // having render items that need updating
+    if (_wasFading && !isStillFading()) {
+        _model->setRenderItemsNeedUpdate();
+    }
+    _wasFading = isStillFading();
+
     gpu::Batch& batch = *(args->_batch);
 
     if (!getShapeKey().isValid()) {

libraries/render-utils/src/MeshPartPayload.h

@@ -12,6 +12,8 @@
 #ifndef hifi_MeshPartPayload_h
 #define hifi_MeshPartPayload_h
 
+#include <Interpolate.h>
+
 #include <gpu/Batch.h>
 
 #include <render/Scene.h>
@@ -85,6 +87,7 @@ public:
     void startFade() { _fadeStartTime = usecTimestampNow(); }
     bool hasStartedFade() { return _hasStartedFade; }
     void setHasStartedFade(bool hasStartedFade) { _hasStartedFade = hasStartedFade; }
+    bool isStillFading() const { return Interpolate::calculateFadeRatio(_fadeStartTime) < 1.0f; }
 
     // Render Item interface
     render::ItemKey getKey() const override;
@@ -108,6 +111,7 @@ public:
 private:
     quint64 _fadeStartTime { 0 };
     bool _hasStartedFade { false };
+    mutable bool _wasFading { false };
 };
 
 namespace render {

libraries/render-utils/src/Model.cpp

@@ -174,6 +174,7 @@ void Model::setOffset(const glm::vec3& offset) {
 void Model::updateRenderItems() {
 
     _needsUpdateClusterMatrices = true;
+    _renderItemsNeedUpdate = false;
 
     // queue up this work for later processing, at the end of update and just before rendering.
     // the application will ensure only the last lambda is actually invoked.

libraries/render-utils/src/Model.h

@@ -103,6 +103,8 @@ public:
     bool isVisible() const { return _isVisible; }
 
     void updateRenderItems();
+    void setRenderItemsNeedUpdate() { _renderItemsNeedUpdate = true; }
+    bool getRenderItemsNeedUpdate() { return _renderItemsNeedUpdate; }
     AABox getRenderableMeshBound() const;
 
     bool maybeStartBlender();
@@ -396,6 +398,8 @@ protected:
 
     bool _geometryRequestFailed { false };
 
+    bool _renderItemsNeedUpdate { false };
+
 private slots:
     void handleGeometryResourceFailure() { _geometryRequestFailed = true; }
 };