Fix issues with components and remove components when entities are destroyed

src/components/ProxyShapesComponents.cpp

@@ -200,7 +200,6 @@ void ProxyShapesComponents::addComponent(Entity entity, bool isSleeping, const P
     linkProxyShapeWithEntity(entity, index);
 
     assert(mSleepingStartIndex <= mNbComponents);
-
     assert(mPreviousBodyProxyShapes[mNextBodyProxyShapes[index]] == index || !hasNextProxyShape(index));
     assert(mNextBodyProxyShapes[mPreviousBodyProxyShapes[index]] == index || !hasPreviousProxyShape(index));
 }
@@ -305,43 +304,6 @@ void ProxyShapesComponents::swapComponents(uint32 index1, uint32 index2) {
     assert(mNextBodyProxyShapes[mPreviousBodyProxyShapes[index2]] == index2 || !hasPreviousProxyShape(index2));
 }
 
-// Perform garbage collection to remove unused components
-void ProxyShapesComponents::garbageCollection(const EntityManager& entityManager) {
-
-    // TODO : Make sure we call this method each frame
-
-    // We use lazy garbage collection. The idea is to pick random components and destroy
-    // them if their corresponding entities have been destroyed. We do this until we hit
-    // GARBAGE_COLLECTION_MAX_VALID_ENTITIES in a row. Therefore, it cost almost nothing
-    // if there are no destroyed entities and it very quickly destroys components where there
-    // are a lot of destroyed entities.
-
-    uint32 nbHitValidEntitiesInARow = 0;
-
-    // For random number generation
-    std::random_device rd;
-    std::mt19937 eng(rd());
-
-    while (mNbComponents > 0 && nbHitValidEntitiesInARow < GARBAGE_COLLECTION_MAX_VALID_ENTITIES) {
-
-        // Select a random index in the components array
-        std::uniform_int_distribution<uint32> distr(0, mNbComponents - 1);
-        uint32 i = distr(eng);
-
-        // If the corresponding entity is valid
-        if (entityManager.isValid(mEntities[i])) {
-            nbHitValidEntitiesInARow++;
-
-            continue;
-        }
-
-        nbHitValidEntitiesInARow = 0;
-
-        // Destroy the component
-        removeComponent(i);
-    }
-}
-
 // Remove a component at a given index
 void ProxyShapesComponents::removeComponent(uint32 index) {
 
@@ -430,12 +392,13 @@ void ProxyShapesComponents::removeComponent(uint32 index) {
         if (mSleepingStartIndex != mNbComponents) {
 
             // We replace the last awake component by the last sleeping component
-            moveComponentToIndex(mNbComponents - 1, index);
+            moveComponentToIndex(mNbComponents - 1, mSleepingStartIndex - 1);
-
-            mSleepingStartIndex--;
         }
+
+        mSleepingStartIndex--;
     }
 
+    assert(mSleepingStartIndex <= mNbComponents);
     mNbComponents--;
 }
 
@@ -454,6 +417,7 @@ bool ProxyShapesComponents::hasNextProxyShape(uint32 index) const {
 // Destroy a component at a given index
 void ProxyShapesComponents::destroyComponent(uint32 index) {
 
+    assert(index < mNbComponents);
 
     mEntities[index].~Entity();
     mLocalBounds[index].~AABB();
@@ -500,3 +464,19 @@ void ProxyShapesComponents::setIsEntitySleeping(Entity entity, bool isSleeping)
     assert(mNextBodyProxyShapes[mPreviousBodyProxyShapes[index]] == index || !hasPreviousProxyShape(index));
 }
 
+// Remove all the components of a given entity
+void ProxyShapesComponents::removeComponents(Entity entity) {
+
+   auto it = mMapEntityToComponentIndex.find(entity);
+
+   // While there are components for this entity
+   while (it != mMapEntityToComponentIndex.end()) {
+
+       // Remove the component
+       removeComponent(it->second);
+
+       it = mMapEntityToComponentIndex.find(entity);
+   }
+
+   assert(!mMapEntityToComponentIndex.containsKey(entity));
+}

src/components/ProxyShapesComponents.h

@@ -169,11 +169,11 @@ class ProxyShapesComponents {
         /// Add a component
         void addComponent(Entity entity, bool isSleeping, const ProxyShapeComponent& component);
 
+        /// Remove all the components of a given entity
+        void removeComponents(Entity entity);
+
         /// Notify if a given entity is sleeping or not
         void setIsEntitySleeping(Entity entity, bool isSleeping);
-
-        /// Perform garbage collection to remove unused components
-        void garbageCollection(const EntityManager& entityManager);
 };
 
 }

src/components/TransformComponents.cpp

@@ -140,45 +140,6 @@ void TransformComponents::addComponent(Entity entity, bool isSleeping, const Tra
     assert(mNbComponents == static_cast<uint32>(mMapEntityToComponentIndex.size()));
 }
 
-// Perform garbage collection to remove unused components
-void TransformComponents::garbageCollection(const EntityManager& entityManager) {
-
-    // TODO : Make sure we call this method each frame
-
-    // We use lazy garbage collection. The idea is to pick random components and destroy
-    // them if their corresponding entities have been destroyed. We do this until we hit
-    // GARBAGE_COLLECTION_MAX_VALID_ENTITIES in a row. Therefore, it cost almost nothing
-    // if there are no destroyed entities and it very quickly destroys components where there
-    // are a lot of destroyed entities.
-
-    uint32 nbHitValidEntitiesInARow = 0;
-
-    // For random number generation
-    std::random_device rd;
-    std::mt19937 eng(rd());
-
-    while (mNbComponents > 0 && nbHitValidEntitiesInARow < GARBAGE_COLLECTION_MAX_VALID_ENTITIES) {
-
-        // Select a random index in the components array
-        std::uniform_int_distribution<uint32> distr(0, mNbComponents - 1);
-        uint32 i = distr(eng);
-
-        // If the corresponding entity is valid
-        if (entityManager.isValid(mEntities[i])) {
-            nbHitValidEntitiesInARow++;
-
-            continue;
-        }
-
-        nbHitValidEntitiesInARow = 0;
-
-        // Destroy the component
-        removeComponent(i);
-    }
-
-    assert(mNbComponents == static_cast<uint32>(mMapEntityToComponentIndex.size()));
-}
-
 // Remove a component at a given index
 void TransformComponents::removeComponent(uint32 index) {
 
@@ -214,14 +175,15 @@ void TransformComponents::removeComponent(uint32 index) {
         if (mSleepingStartIndex != mNbComponents) {
 
             // We replace the last awake component by the last sleeping component
-            moveComponentToIndex(mNbComponents - 1, index);
+            moveComponentToIndex(mNbComponents - 1, mSleepingStartIndex - 1);
-
-            mSleepingStartIndex--;
         }
+
+        mSleepingStartIndex--;
     }
 
     mNbComponents--;
 
+    assert(mSleepingStartIndex <= mNbComponents);
     assert(mNbComponents == static_cast<uint32>(mMapEntityToComponentIndex.size()));
 }
 
@@ -309,8 +271,26 @@ void TransformComponents::swapComponents(uint32 index1, uint32 index2) {
 // Destroy a component at a given index
 void TransformComponents::destroyComponent(uint32 index) {
 
+    assert(index < mNbComponents);
+    assert(mMapEntityToComponentIndex[mEntities[index]] == index);
+
     mMapEntityToComponentIndex.remove(mEntities[index]);
 
     mEntities[index].~Entity();
     mTransforms[index].~Transform();
 }
+
+// Remove all the components of a given entity
+void TransformComponents::removeComponents(Entity entity) {
+
+    auto it = mMapEntityToComponentIndex.find(entity);
+
+    // If there is a component for this entity
+    if (it != mMapEntityToComponentIndex.end()) {
+
+        // Remove the component
+        removeComponent(it->second);
+    }
+
+   assert(!mMapEntityToComponentIndex.containsKey(entity));
+}

src/components/TransformComponents.h

@@ -105,8 +105,8 @@ class TransformComponents : public Components {
         /// Add a component
         void addComponent(Entity entity, bool isSleeping, const TransformComponent& component);
 
-        /// Perform garbage collection to remove unused components
+        /// Remove all the components of a given entity
-        void garbageCollection(const EntityManager& entityManager);
+        void removeComponents(Entity entity);
 
         /// Return the transform of an entity
         Transform& getTransform(Entity entity) const;

src/engine/CollisionWorld.cpp

@@ -197,8 +197,8 @@ void CollisionWorld::destroyCollisionBody(CollisionBody* collisionBody) {
     // Reset the contact manifold list of the body
     collisionBody->resetContactManifoldsList();
 
-    // Destroy the corresponding entity
+    // Destroy the entity and its components
-    mEntityManager.destroyEntity(collisionBody->getEntity());
+    destroyEntity(collisionBody->getEntity());
 
     // Call the destructor of the collision body
     collisionBody->~CollisionBody();
@@ -248,6 +248,19 @@ void CollisionWorld::notifyBodySleeping(Entity entity, bool isSleeping) {
     mProxyShapesComponents.setIsEntitySleeping(entity, isSleeping);
 }
 
+// Destroy an entity and all the associated components
+void CollisionWorld::destroyEntity(Entity entity) {
+
+    // Destroy the corresponding entity
+    mEntityManager.destroyEntity(entity);
+
+    // TODO : Make sure we notify all the components here ...
+
+    // Notify all the components
+    mTransformComponents.removeComponents(entity);
+    mProxyShapesComponents.removeComponents(entity);
+}
+
 // Test if the AABBs of two bodies overlap
 /**
  * @param body1 Pointer to the first body to test

src/engine/CollisionWorld.h

@@ -128,6 +128,9 @@ class CollisionWorld {
         /// Notify the world if a body is sleeping or not
         void notifyBodySleeping(Entity entity, bool isSleeping);
 
+        /// Destroy an entity and all the associated components
+        void destroyEntity(Entity entity);
+
     public :
 
         // -------------------- Methods -------------------- //

src/engine/DynamicsWorld.cpp

@@ -479,8 +479,8 @@ void DynamicsWorld::destroyRigidBody(RigidBody* rigidBody) {
     // Reset the contact manifold list of the body
     rigidBody->resetContactManifoldsList();
 
-    // Destroy the corresponding entity
+    // Destroy the corresponding entity and its components
-    mEntityManager.destroyEntity(rigidBody->getEntity());
+    destroyEntity(rigidBody->getEntity());
 
     // Call the destructor of the rigid body
     rigidBody->~RigidBody();