First working fade

libraries/avatars-renderer/src/avatars-renderer/Avatar.cpp

@@ -61,7 +61,7 @@ namespace render {
     template <> uint32_t metaFetchMetaSubItems(const AvatarSharedPointer& avatar, ItemIDs& subItems) {
         auto avatarPtr = static_pointer_cast<Avatar>(avatar);
         if (avatarPtr->getSkeletonModel()) {
-            auto metaSubItems = avatarPtr->getSkeletonModel()->fetchRenderItemIDs();
+            auto& metaSubItems = avatarPtr->getSkeletonModel()->fetchRenderItemIDs();
             subItems.insert(subItems.end(), metaSubItems.begin(), metaSubItems.end());
             return (uint32_t) metaSubItems.size();
         }

libraries/entities-renderer/src/RenderableModelEntityItem.cpp

@@ -217,8 +217,9 @@ namespace render {
     }
     template <> uint32_t metaFetchMetaSubItems(const RenderableModelEntityItemMeta::Pointer& payload, ItemIDs& subItems) {
         auto modelEntity = std::static_pointer_cast<RenderableModelEntityItem>(payload->entity);
-        if (modelEntity->hasModel()) {
-            auto metaSubItems = modelEntity->getModelNotSafe()->fetchRenderItemIDs();
+        auto model = modelEntity->getModelNotSafe();
+        if (modelEntity->hasModel() && model) {
+            auto& metaSubItems = model->fetchRenderItemIDs();
             subItems.insert(subItems.end(), metaSubItems.begin(), metaSubItems.end());
             return (uint32_t) metaSubItems.size();
         }
@@ -489,6 +490,17 @@ ModelPointer RenderableModelEntityItem::getModelNotSafe() {
     return _model;
 }
 
+void RenderableModelEntityItem::setModelURLFinished(bool success) {
+    if (success) {
+        const render::ScenePointer& scene = AbstractViewStateInterface::instance()->getMain3DScene();
+        render::Transaction transaction;
+
+        const auto& item = scene->getItem(_myMetaItem);
+        transaction.transitionItem(_myMetaItem, render::Transition::ELEMENT_ENTER_LEAVE_DOMAIN);
+        scene->enqueueTransaction(transaction);
+    }
+}
+
 ModelPointer RenderableModelEntityItem::getModel() {
     // make sure our renderer is setup
     if (!_myRenderer) {
@@ -506,6 +518,7 @@ ModelPointer RenderableModelEntityItem::getModel() {
         // If we don't have a model, allocate one *immediately*
         if (!_model) {
             _model = _myRenderer->allocateModel(getModelURL(), _myRenderer->getEntityLoadingPriority(*this), this);
+            QObject::connect(_model.get(), &Model::setURLFinished, this, &RenderableModelEntityItem::setModelURLFinished);
             _needsInitialSimulation = true;
         // If we need to change URLs, update it *after rendering* (to avoid access violations)
         } else if (QUrl(getModelURL()) != _model->getURL()) {

libraries/entities-renderer/src/RenderableModelEntityItem.h

@@ -12,16 +12,21 @@
 #ifndef hifi_RenderableModelEntityItem_h
 #define hifi_RenderableModelEntityItem_h
 
+#include <QObject>
 #include <QString>
 #include <QStringList>
 
 #include <ModelEntityItem.h>
 #include <AnimationCache.h>
+#include <model-networking\ModelCache.h>
+
+#include "RenderableEntityItem.h"
 
 class Model;
 class EntityTreeRenderer;
 
-class RenderableModelEntityItem : public ModelEntityItem, RenderableEntityInterface {
+class RenderableModelEntityItem : public QObject, public ModelEntityItem, RenderableEntityInterface {
+    Q_OBJECT
 public:
     static EntityItemPointer factory(const EntityItemID& entityID, const EntityItemProperties& properties);
 
@@ -116,6 +121,10 @@ public:
         return _animation;
     }
 
+public slots:
+
+    void setModelURLFinished(bool success);
+
 private:
     QVariantMap parseTexturesToMap(QString textures);
     void remapTextures();

libraries/render-utils/src/FadeEffect.cpp

@@ -464,6 +464,7 @@ FadeJob::FadeJob()
 {
 	auto texturePath = PathUtils::resourcesPath() + "images/fadeMask.png";
 	_fadeMaskMap = DependencyManager::get<TextureCache>()->getImageTexture(texturePath, image::TextureUsage::STRICT_TEXTURE);
+    _previousTime = usecTimestampNow();
 }
 
 void FadeJob::configure(const Config& config) {
@@ -493,76 +494,91 @@ void FadeJob::run(const render::RenderContextPointer& renderContext) {
     auto transitionStage = scene->getStage<render::TransitionStage>(render::TransitionStage::getName());
     uint64_t now = usecTimestampNow();
     const double deltaTime = (int64_t(now) - int64_t(_previousTime)) / double(USECS_PER_SECOND);
+    render::Transaction transaction;
+    bool hasTransactions = false;
 
     // And now update fade effect
     for (auto transitionId : *transitionStage) {
         auto& state = transitionStage->editTransition(transitionId);
-        update(*jobConfig, scene, state, deltaTime);
+        if (!update(*jobConfig, scene, state, deltaTime)) {
+            // Remove transition for this item
+            transaction.transitionItem(state.itemId, render::Transition::NONE);
+            hasTransactions = true;
+        }
     }
 
+    if (hasTransactions) {
+        scene->enqueueTransaction(transaction);
+    }
     _previousTime = now;
 }
 
-void FadeJob::update(const Config& config, const render::ScenePointer& scene, render::Transition& transition, const double deltaTime) const {
+bool FadeJob::update(const Config& config, const render::ScenePointer& scene, render::Transition& transition, const double deltaTime) const {
     auto& eventConfig = config.events[transition.eventType];
     auto& item = scene->getItem(transition.itemId);
-    auto& aabb = item.getBound();
-    auto& dimensions = aabb.getDimensions();
     const double eventDuration = (double)eventConfig.duration;
     const FadeConfig::Timing timing = (FadeConfig::Timing) eventConfig.timing;
+    bool continueTransition = true;
 
-    assert(timing < render::Transition::EVENT_CATEGORY_COUNT);
+    if (item.exist()) {
+        auto& aabb = item.getBound();
+        auto& dimensions = aabb.getDimensions();
 
-    switch (transition.eventType) {
-    case render::Transition::ELEMENT_ENTER_LEAVE_DOMAIN:
-        transition.threshold = 1.f - computeElementEnterThreshold(transition.time, eventConfig.duration, timing);
-        transition.threshold = (transition.threshold - 0.5f)*_thresholdScale[transition.eventType] + 0.5f;
-        transition.noiseOffset = aabb.calcCenter();
-        transition.baseOffset = transition.noiseOffset - dimensions.y;
-        transition.baseInvSize.x = 1.f / dimensions.x;
-        transition.baseInvSize.y = 1.f / dimensions.y;
-        transition.baseInvSize.z = 1.f / dimensions.z;
+        assert(timing < render::Transition::EVENT_CATEGORY_COUNT);
+
+        switch (transition.eventType) {
+        case render::Transition::ELEMENT_ENTER_LEAVE_DOMAIN:
+            transition.threshold = 1.f - computeElementEnterRatio(transition.time, eventConfig.duration, timing);
+            transition.threshold = (transition.threshold - 0.5f)*_thresholdScale[transition.eventType] + 0.5f;
+            transition.noiseOffset = aabb.calcCenter();
+            transition.baseOffset = transition.noiseOffset - dimensions.y;
+            transition.baseInvSize.x = 1.f / dimensions.x;
+            transition.baseInvSize.y = 1.f / dimensions.y;
+            transition.baseInvSize.z = 1.f / dimensions.z;
+            continueTransition = transition.threshold > 0.f;
+            break;
+
+        case render::Transition::BUBBLE_ISECT_OWNER:
+        {
+            /*       const glm::vec3 cameraPos = renderContext->args->getViewFrustum().getPosition();
+            glm::vec3 delta = itemBounds.bound.calcCenter() - cameraPos;
+            float distance = glm::length(delta);
+
+            delta = glm::normalize(delta) * std::max(0.f, distance - 0.5f);
+
+            _editBaseOffset = cameraPos + delta*_editThreshold;
+            _editThreshold = 0.33f;*/
+        }
         break;
 
-    case render::Transition::BUBBLE_ISECT_OWNER:
-    {
- /*       const glm::vec3 cameraPos = renderContext->args->getViewFrustum().getPosition();
-        glm::vec3 delta = itemBounds.bound.calcCenter() - cameraPos;
-        float distance = glm::length(delta);
-
-        delta = glm::normalize(delta) * std::max(0.f, distance - 0.5f);
-
-        _editBaseOffset = cameraPos + delta*_editThreshold;
-        _editThreshold = 0.33f;*/
-    }
-    break;
-
-    case render::Transition::BUBBLE_ISECT_TRESPASSER:
-    {
-    //    _editBaseOffset = glm::vec3{ 0.f, 0.f, 0.f };
-    }
-    break;
-
-    case render::Transition::USER_ENTER_LEAVE_DOMAIN:
-    {
-/*        _editBaseOffset = itemBounds.bound.calcCenter();
-        _editBaseOffset.y -= itemBounds.bound.getDimensions().y / 2.f;*/
-    }
-    break;
-
-    case render::Transition::AVATAR_CHANGE:
+        case render::Transition::BUBBLE_ISECT_TRESPASSER:
+        {
+            //    _editBaseOffset = glm::vec3{ 0.f, 0.f, 0.f };
+        }
         break;
 
-    default:
-        assert(false);
+        case render::Transition::USER_ENTER_LEAVE_DOMAIN:
+        {
+            /*        _editBaseOffset = itemBounds.bound.calcCenter();
+            _editBaseOffset.y -= itemBounds.bound.getDimensions().y / 2.f;*/
+        }
+        break;
+
+        case render::Transition::AVATAR_CHANGE:
+            break;
+
+        default:
+            assert(false);
+        }
     }
 
     transition.time += deltaTime;
 
 //    renderContext->jobConfig->setProperty("threshold", threshold);
+    return continueTransition;
 }
 
-float FadeJob::computeElementEnterThreshold(double time, const double period, FadeConfig::Timing timing) const {
+float FadeJob::computeElementEnterRatio(double time, const double period, FadeConfig::Timing timing) {
     assert(period > 0.0);
     float fadeAlpha = 1.0f;
     const double INV_FADE_PERIOD = 1.0 / period;

libraries/render-utils/src/FadeEffect.h

@@ -193,8 +193,8 @@ private:
     float _thresholdScale[render::Transition::EVENT_CATEGORY_COUNT];
     uint64_t _previousTime{ 0 };
 
-    void update(const Config& config, const render::ScenePointer& scene, render::Transition& transition, const double deltaTime) const;
-    float computeElementEnterThreshold(double time, const double period, FadeConfig::Timing timing) const;
+    bool update(const Config& config, const render::ScenePointer& scene, render::Transition& transition, const double deltaTime) const;
+    static float computeElementEnterRatio(double time, const double period, FadeConfig::Timing timing);
 
     const render::Item* findNearestItem(const render::RenderContextPointer& renderContext, const render::Varying& input, float& minIsectDistance) const;
 };

libraries/render-utils/src/RenderPipelines.cpp

@@ -104,7 +104,8 @@ void initDeferredPipelines(ShapePlumber& plumber, const render::ShapePipeline::B
 void initForwardPipelines(ShapePlumber& plumber);
 
 void addPlumberPipeline(ShapePlumber& plumber,
-        const ShapeKey& key, const gpu::ShaderPointer& vertex, const gpu::ShaderPointer& pixel);
+        const ShapeKey& key, const gpu::ShaderPointer& vertex, const gpu::ShaderPointer& pixel,
+        const render::ShapePipeline::BatchSetter& batchSetter, const render::ShapePipeline::ItemSetter& itemSetter);
 
 void batchSetter(const ShapePipeline& pipeline, gpu::Batch& batch, RenderArgs* args);
 void lightBatchSetter(const ShapePipeline& pipeline, gpu::Batch& batch, RenderArgs* args);
@@ -228,30 +229,30 @@ void initDeferredPipelines(render::ShapePlumber& plumber, const render::ShapePip
     auto simpleTranslucentUnlitFadePixel = gpu::Shader::createPixel(std::string(simple_transparent_textured_unlit_fade_frag));
 
     using Key = render::ShapeKey;
-    auto addPipeline = std::bind(&addPlumberPipeline, std::ref(plumber), _1, _2, _3);
+    auto addPipeline = std::bind(&addPlumberPipeline, std::ref(plumber), _1, _2, _3, _4, _5);
     // TODO: Refactor this to use a filter
     // Opaques
     addPipeline(
         Key::Builder().withMaterial(),
-        modelVertex, modelPixel);
+        modelVertex, modelPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder(),
-        simpleVertex, simplePixel);
+        simpleVertex, simplePixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withUnlit(),
-        modelVertex, modelUnlitPixel);
+        modelVertex, modelUnlitPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withUnlit(),
-        simpleVertex, simpleUnlitPixel);
+        simpleVertex, simpleUnlitPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withTangents(),
-        modelNormalMapVertex, modelNormalMapPixel);
+        modelNormalMapVertex, modelNormalMapPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withSpecular(),
-        modelVertex, modelSpecularMapPixel);
+        modelVertex, modelSpecularMapPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withTangents().withSpecular(),
-        modelNormalMapVertex, modelNormalSpecularMapPixel);
+        modelNormalMapVertex, modelNormalSpecularMapPixel, nullptr, nullptr);
     // Same thing but with Fade on
     addPipeline(
         Key::Builder().withMaterial().withFade(),
@@ -278,29 +279,29 @@ void initDeferredPipelines(render::ShapePlumber& plumber, const render::ShapePip
     // Translucents
     addPipeline(
         Key::Builder().withMaterial().withTranslucent(),
-        modelVertex, modelTranslucentPixel);
+        modelVertex, modelTranslucentPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withTranslucent(),
-        simpleVertex, simpleTranslucentPixel);
+        simpleVertex, simpleTranslucentPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withTranslucent().withUnlit(),
-        modelVertex, modelTranslucentUnlitPixel);
+        modelVertex, modelTranslucentUnlitPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withTranslucent().withUnlit(),
-        simpleVertex, simpleTranslucentUnlitPixel);
+        simpleVertex, simpleTranslucentUnlitPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withTranslucent().withTangents(),
-        modelNormalMapVertex, modelTranslucentPixel);
+        modelNormalMapVertex, modelTranslucentPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withTranslucent().withSpecular(),
-        modelVertex, modelTranslucentPixel);
+        modelVertex, modelTranslucentPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withTranslucent().withTangents().withSpecular(),
-        modelNormalMapVertex, modelTranslucentPixel);
+        modelNormalMapVertex, modelTranslucentPixel, nullptr, nullptr);
     addPipeline(
         // FIXME: Ignore lightmap for translucents meshpart
         Key::Builder().withMaterial().withTranslucent().withLightmap(),
-        modelVertex, modelTranslucentPixel);
+        modelVertex, modelTranslucentPixel, nullptr, nullptr);
     // Same thing but with Fade on
     addPipeline(
         Key::Builder().withMaterial().withTranslucent().withFade(),
@@ -331,16 +332,16 @@ void initDeferredPipelines(render::ShapePlumber& plumber, const render::ShapePip
     // Lightmapped
     addPipeline(
         Key::Builder().withMaterial().withLightmap(),
-        modelLightmapVertex, modelLightmapPixel);
+        modelLightmapVertex, modelLightmapPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withLightmap().withTangents(),
-        modelLightmapNormalMapVertex, modelLightmapNormalMapPixel);
+        modelLightmapNormalMapVertex, modelLightmapNormalMapPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withLightmap().withSpecular(),
-        modelLightmapVertex, modelLightmapSpecularMapPixel);
+        modelLightmapVertex, modelLightmapSpecularMapPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withLightmap().withTangents().withSpecular(),
-        modelLightmapNormalMapVertex, modelLightmapNormalSpecularMapPixel);
+        modelLightmapNormalMapVertex, modelLightmapNormalSpecularMapPixel, nullptr, nullptr);
     // Same thing but with Fade on
     addPipeline(
         Key::Builder().withMaterial().withLightmap().withFade(),
@@ -358,16 +359,16 @@ void initDeferredPipelines(render::ShapePlumber& plumber, const render::ShapePip
     // Skinned
     addPipeline(
         Key::Builder().withMaterial().withSkinned(),
-        skinModelVertex, modelPixel);
+        skinModelVertex, modelPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withSkinned().withTangents(),
-        skinModelNormalMapVertex, modelNormalMapPixel);
+        skinModelNormalMapVertex, modelNormalMapPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withSkinned().withSpecular(),
-        skinModelVertex, modelSpecularMapPixel);
+        skinModelVertex, modelSpecularMapPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withSkinned().withTangents().withSpecular(),
-        skinModelNormalMapVertex, modelNormalSpecularMapPixel);
+        skinModelNormalMapVertex, modelNormalSpecularMapPixel, nullptr, nullptr);
     // Same thing but with Fade on
     addPipeline(
         Key::Builder().withMaterial().withSkinned().withFade(),
@@ -385,16 +386,16 @@ void initDeferredPipelines(render::ShapePlumber& plumber, const render::ShapePip
     // Skinned and Translucent
     addPipeline(
         Key::Builder().withMaterial().withSkinned().withTranslucent(),
-        skinModelVertex, modelTranslucentPixel);
+        skinModelVertex, modelTranslucentPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withSkinned().withTranslucent().withTangents(),
-        skinModelNormalMapVertex, modelTranslucentPixel);
+        skinModelNormalMapVertex, modelTranslucentPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withSkinned().withTranslucent().withSpecular(),
-        skinModelVertex, modelTranslucentPixel);
+        skinModelVertex, modelTranslucentPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withMaterial().withSkinned().withTranslucent().withTangents().withSpecular(),
-        skinModelNormalMapVertex, modelTranslucentPixel);
+        skinModelNormalMapVertex, modelTranslucentPixel, nullptr, nullptr);
     // Same thing but with Fade on
     addPipeline(
         Key::Builder().withMaterial().withSkinned().withTranslucent().withFade(),
@@ -412,10 +413,10 @@ void initDeferredPipelines(render::ShapePlumber& plumber, const render::ShapePip
     // Depth-only
     addPipeline(
         Key::Builder().withDepthOnly(),
-        modelShadowVertex, modelShadowPixel);
+        modelShadowVertex, modelShadowPixel, nullptr, nullptr);
     addPipeline(
         Key::Builder().withSkinned().withDepthOnly(),
-        skinModelShadowVertex, modelShadowPixel);
+        skinModelShadowVertex, modelShadowPixel, nullptr, nullptr);
     // Same thing but with Fade on
     addPipeline(
         Key::Builder().withDepthOnly().withFade(),
@@ -440,7 +441,7 @@ void initForwardPipelines(render::ShapePlumber& plumber) {
     auto modelNormalSpecularMapPixel = gpu::Shader::createPixel(std::string(forward_model_normal_specular_map_frag));
 
     using Key = render::ShapeKey;
-    auto addPipeline = std::bind(&addPlumberPipeline, std::ref(plumber), _1, _2, _3);
+    auto addPipeline = std::bind(&addPlumberPipeline, std::ref(plumber), _1, _2, _3, nullptr, nullptr);
     // Opaques
     addPipeline(
         Key::Builder().withMaterial(),
@@ -473,7 +474,8 @@ void initForwardPipelines(render::ShapePlumber& plumber) {
 }
 
 void addPlumberPipeline(ShapePlumber& plumber,
-        const ShapeKey& key, const gpu::ShaderPointer& vertex, const gpu::ShaderPointer& pixel) {
+        const ShapeKey& key, const gpu::ShaderPointer& vertex, const gpu::ShaderPointer& pixel,
+        const render::ShapePipeline::BatchSetter& extraBatchSetter, const render::ShapePipeline::ItemSetter& itemSetter) {
     // These key-values' pipelines are added by this functor in addition to the key passed
     assert(!key.isWireframe());
     assert(!key.isDepthBiased());
@@ -510,8 +512,18 @@ void addPlumberPipeline(ShapePlumber& plumber,
             state->setDepthBiasSlopeScale(1.0f);
         }
 
-        plumber.addPipeline(builder.build(), program, state,
-                key.isTranslucent() ? &lightBatchSetter : &batchSetter);
+        auto baseBatchSetter = key.isTranslucent() ? &lightBatchSetter : &batchSetter;
+        render::ShapePipeline::BatchSetter finalBatchSetter;
+        if (extraBatchSetter) {
+            finalBatchSetter = [baseBatchSetter, extraBatchSetter](const ShapePipeline& pipeline, gpu::Batch& batch, render::Args* args) {
+                baseBatchSetter(pipeline, batch, args);
+                extraBatchSetter(pipeline, batch, args);
+            };
+        }
+        else {
+            finalBatchSetter = baseBatchSetter;
+        }
+        plumber.addPipeline(builder.build(), program, state, finalBatchSetter, itemSetter);
     }
 }
 

libraries/render/src/render/Scene.cpp

@@ -13,6 +13,7 @@
 #include <numeric>
 #include <gpu/Batch.h>
 #include "Logging.h"
+#include "TransitionStage.h"
 
 using namespace render;
 
@@ -30,6 +31,11 @@ void Transaction::removeItem(ItemID id) {
     _removedItems.emplace_back(id);
 }
 
+void Transaction::transitionItem(ItemID id, Transition::Type transition) {
+    _transitioningItems.emplace_back(id);
+    _transitionTypes.emplace_back(transition);
+}
+
 void Transaction::updateItem(ItemID id, const UpdateFunctorPointer& functor) {
     _updatedItems.emplace_back(id);
     _updateFunctors.emplace_back(functor);
@@ -46,6 +52,8 @@ void Transaction::merge(const Transaction& transaction) {
     _updatedItems.insert(_updatedItems.end(), transaction._updatedItems.begin(), transaction._updatedItems.end());
     _updateFunctors.insert(_updateFunctors.end(), transaction._updateFunctors.begin(), transaction._updateFunctors.end());
     _resetSelections.insert(_resetSelections.end(), transaction._resetSelections.begin(), transaction._resetSelections.end());
+    _transitioningItems.insert(_transitioningItems.end(), transaction._transitioningItems.begin(), transaction._transitioningItems.end());
+    _transitionTypes.insert(_transitionTypes.end(), transaction._transitionTypes.begin(), transaction._transitionTypes.end());
 }
 
 
@@ -115,6 +123,9 @@ void Scene::processTransactionQueue() {
         // removes
         removeItems(consolidatedTransaction._removedItems);
 
+        // Transitions
+        transitionItems(consolidatedTransaction._transitioningItems, consolidatedTransaction._transitionTypes);
+
         // Update the numItemsAtomic counter AFTER the pending changes went through
         _numAllocatedItems.exchange(maxID);
     }
@@ -216,6 +227,67 @@ void Scene::updateItems(const ItemIDs& ids, UpdateFunctors& functors) {
     }
 }
 
+void Scene::transitionItems(const ItemIDs& ids, const TransitionTypes& types) {
+    auto transitionType = types.begin();
+    auto transitionStage = getStage<TransitionStage>(TransitionStage::getName());
+
+    for (auto itemId : ids) {
+        auto transitionId = INVALID_INDEX;
+
+        if (*transitionType != Transition::NONE) {
+            transitionId = transitionStage->addTransition(itemId, *transitionType);
+        }
+
+        setItemTransition(itemId, transitionId);
+        // next loop
+        transitionType++;
+    }
+}
+
+void Scene::collectSubItems(ItemID parentId, ItemIDs& subItems) const {
+    // Access the true item
+    auto& item = _items[parentId];
+
+    if (item.exist()) {
+        // Recursivelly collect the subitems
+        auto subItemBeginIndex = subItems.size();
+        auto subItemCount = item.fetchMetaSubItems(subItems);
+        for (auto i = subItemBeginIndex; i < (subItemBeginIndex + subItemCount); i++) {
+            collectSubItems(subItems[i], subItems);
+        }
+    }
+}
+
+void Scene::setItemTransition(ItemID itemId, Index transitionId) {
+    // Access the true item
+    auto& item = _items[itemId];
+
+    if (item.exist()) {
+        ItemIDs subItems;
+
+        item.setTransitionId(transitionId);
+
+        // Sub-items share the same transition Id
+        collectSubItems(itemId, subItems);
+        for (auto subItemId : subItems) {
+            auto& subItem = _items[subItemId];
+            subItem.setTransitionId(transitionId);
+        }
+    }
+    else {
+        qWarning() << "Collecting sub items on item without payload";
+    }
+}
+
+void Scene::resetItemTransition(ItemID itemId) {
+    // Access the true item
+    auto& item = _items[itemId];
+    auto transitionStage = getStage<TransitionStage>(TransitionStage::getName());
+
+    transitionStage->removeTransition(item.getTransitionId());
+    setItemTransition(itemId, Transition::NONE);
+}
+
 // THis fucntion is thread safe
 Selection Scene::getSelection(const Selection::Name& name) const {
     std::unique_lock<std::mutex> lock(_selectionsMutex);

libraries/render/src/render/Scene.h

@@ -16,6 +16,7 @@
 #include "SpatialTree.h"
 #include "Stage.h"
 #include "Selection.h"
+#include "Transition.h"
 
 namespace render {
 
@@ -39,6 +40,8 @@ public:
     void resetItem(ItemID id, const PayloadPointer& payload);
     void removeItem(ItemID id);
 
+    void transitionItem(ItemID id, Transition::Type transition);
+
     template <class T> void updateItem(ItemID id, std::function<void(T&)> func) {
         updateItem(id, std::make_shared<UpdateFunctor<T>>(func));
     }
@@ -54,10 +57,12 @@ public:
     // Checkers if there is work to do when processing the transaction
     bool touchTransactions() const { return !_resetSelections.empty(); }
 
-    ItemIDs _resetItems; 
+    ItemIDs _resetItems;
     Payloads _resetPayloads;
     ItemIDs _removedItems;
     ItemIDs _updatedItems;
+    ItemIDs _transitioningItems;
+    TransitionTypes _transitionTypes;
     UpdateFunctors _updateFunctors;
 
     Selections _resetSelections;
@@ -123,6 +128,8 @@ public:
     }
     void resetStage(const Stage::Name& name, const StagePointer& stage);
 
+    void setItemTransition(ItemID id, Index transitionId);
+    void resetItemTransition(ItemID id);
 
 protected:
     // Thread safe elements that can be accessed from anywhere
@@ -141,6 +148,9 @@ protected:
     void resetItems(const ItemIDs& ids, Payloads& payloads);
     void removeItems(const ItemIDs& ids);
     void updateItems(const ItemIDs& ids, UpdateFunctors& functors);
+    void transitionItems(const ItemIDs& ids, const TransitionTypes& types);
+
+    void collectSubItems(ItemID parentId, ItemIDs& subItems) const;
 
     // The Selection map
     mutable std::mutex _selectionsMutex; // mutable so it can be used in the thread safe getSelection const method

libraries/render/src/render/Transition.h

@@ -27,7 +27,8 @@ namespace render {
             AVATAR_CHANGE,
 
             // Don't forget to modify Fade.slh to reflect the change in number of categories
-            EVENT_CATEGORY_COUNT
+            EVENT_CATEGORY_COUNT,
+            NONE = EVENT_CATEGORY_COUNT
         };
 
         Type eventType{ ELEMENT_ENTER_LEAVE_DOMAIN };
@@ -41,6 +42,7 @@ namespace render {
     };
 
     typedef std::shared_ptr<Transition> TransitionPointer;
+    typedef std::vector<Transition::Type> TransitionTypes;
 }
 
 #endif // hifi_render_Transition_h