Allow emitters to be attached to nodes after particle systems

components/nifosg/nifloader.cpp

@@ -219,6 +219,9 @@ namespace NifOsg
         size_t mFirstRootTextureIndex = -1;
         bool mFoundFirstRootTexturingProperty = false;
 
+        // This is used to queue emitters that weren't attached to their node yet.
+        std::vector<std::pair<size_t, osg::ref_ptr<Emitter>>> mEmitterQueue;
+
         static void loadKf(Nif::NIFFilePtr nif, KeyframeHolder& target)
         {
             if(nif->numRoots() < 1)
@@ -290,6 +293,9 @@ namespace NifOsg
 
             osg::ref_ptr<osg::Node> created = handleNode(nifNode, nullptr, imageManager, std::vector<unsigned int>(), 0, false, false, false, &textkeys->mTextKeys);
 
+            // Attach particle emitters to their nodes which should all be loaded by now.
+            handleQueuedParticleEmitters(created, nif);
+
             if (nif->getUseSkinning())
             {
                 osg::ref_ptr<SceneUtil::Skeleton> skel = new SceneUtil::Skeleton;
@@ -979,6 +985,27 @@ namespace NifOsg
             return emitter;
         }
 
+        void handleQueuedParticleEmitters(osg::Node* rootNode, Nif::NIFFilePtr nif)
+        {
+            for (const auto& emitterPair : mEmitterQueue)
+            {
+                size_t recIndex = emitterPair.first;
+                FindGroupByRecIndex findEmitterNode(recIndex);
+                rootNode->accept(findEmitterNode);
+                osg::Group* emitterNode = findEmitterNode.mFound;
+                if (!emitterNode)
+                {
+                    nif->warn("Failed to find particle emitter emitter node (node record index " + std::to_string(recIndex) + ")");
+                    continue;
+                }
+
+                // Emitter attached to the emitter node. Note one side effect of the emitter using the CullVisitor is that hiding its node
+                // actually causes the emitter to stop firing. Convenient, because MW behaves this way too!
+                emitterNode->addChild(emitterPair.second);
+            }
+            mEmitterQueue.clear();
+        }
+
         void handleParticleSystem(const Nif::Node *nifNode, osg::Group *parentNode, SceneUtil::CompositeStateSetUpdater* composite, int animflags, osg::Node* rootNode)
         {
             osg::ref_ptr<ParticleSystem> partsys (new ParticleSystem);
@@ -1028,22 +1055,8 @@ namespace NifOsg
                 emitter->setParticleSystem(partsys);
                 emitter->setReferenceFrame(osgParticle::ParticleProcessor::RELATIVE_RF);
 
-                // Note: we assume that the Emitter node is placed *before* the Particle node in the scene graph.
-                // This seems to be true for all NIF files in the game that I've checked, suggesting that NIFs work similar to OSG with regards to update order.
-                // If something ever violates this assumption, the worst that could happen is the culling being one frame late, which wouldn't be a disaster.
-
-                FindGroupByRecIndex find (partctrl->emitter->recIndex);
-                rootNode->accept(find);
-                if (!find.mFound)
-                {
-                    Log(Debug::Info) << "can't find emitter node, wrong node order? in " << mFilename;
-                    return;
-                }
-                osg::Group* emitterNode = find.mFound;
-
-                // Emitter attached to the emitter node. Note one side effect of the emitter using the CullVisitor is that hiding its node
-                // actually causes the emitter to stop firing. Convenient, because MW behaves this way too!
-                emitterNode->addChild(emitter);
+                // The emitter node may not actually be handled yet, so let's delay attaching the emitter to a later moment.
+                mEmitterQueue.emplace_back(partctrl->emitter->recIndex, emitter);
 
                 osg::ref_ptr<ParticleSystemController> callback(new ParticleSystemController(partctrl));
                 setupController(partctrl, callback, animflags);