Adapted Escape the Dawn engine.

src/World.cpp

@@ -0,0 +1,132 @@
+#include "PrecompiledHeader.h"
+#include "World.h"
+
+void World::RecycleEntityID(EntityID id)
+{
+	m_RecycledEntityIDs.push(id);
+}
+
+EntityID World::GenerateEntityID()
+{
+	if (!m_RecycledEntityIDs.empty()) {
+		EntityID id = m_RecycledEntityIDs.top();
+		m_RecycledEntityIDs.pop();
+		return id;
+	} else {
+		return ++m_LastEntityID;
+	}
+}
+
+void World::RecursiveUpdate(std::shared_ptr<System> system, double dt, EntityID parentEntity)
+{
+	for (auto pair : m_EntityParents) {
+		EntityID child = pair.first;
+		EntityID parent = pair.second;
+
+		if (parent == parentEntity)	{
+			system->UpdateEntity(dt, child, parent);
+			RecursiveUpdate(system, dt, child);
+		}
+	}
+}
+
+void World::Update(double dt)
+{
+	for (auto pair : m_Systems) {
+		auto system = pair.second;
+		system->Update(dt);
+		RecursiveUpdate(system, dt, 0);
+	}
+
+	ProcessEntityRemovals();
+}
+
+//std::vector<EntityID> GetEntityChildren(EntityID entity);
+//{
+//	std::vector<EntityID> children;
+//	auto range = m_SceneGraph.equal_range(entity);
+//	for (auto it = range.first; it != range.second; ++it)
+//		children.push_back(it->second);
+//	return children;
+//}
+
+EntityID World::GetEntityParent(EntityID entity)
+{
+	auto it = m_EntityParents.find(entity);
+	return it == m_EntityParents.end() ? 0 : it->second;
+}
+
+bool World::ValidEntity(EntityID entity)
+{
+	return m_EntityParents.find(entity) != m_EntityParents.end();
+}
+
+void World::RemoveEntity(EntityID entity)
+{
+	m_EntitiesToRemove.push_back(entity);
+	for (auto pair : m_EntityParents) {
+		if (pair.second == entity) {
+			m_EntitiesToRemove.push_back(pair.first);
+		}
+	}
+}
+
+void World::ProcessEntityRemovals()
+{
+	for (auto entity : m_EntitiesToRemove) {
+		m_EntityParents.erase(entity);
+		// Remove components
+		for (auto pair : m_EntityComponents[entity]) {
+			auto type = pair.first;
+			auto component = pair.second;
+			// Trigger events
+			for (auto pair : m_Systems) {
+				auto system = pair.second;
+				system->OnComponentRemoved(type, component.get());
+			}
+			m_ComponentsOfType[type].remove(component);
+		}
+		m_EntityComponents.erase(entity);
+
+		RecycleEntityID(entity);
+	}
+	m_EntitiesToRemove.clear();
+}
+
+EntityID World::CreateEntity(EntityID parent /*= 0*/)
+{
+	EntityID newEntity = GenerateEntityID();
+	m_EntityParents.insert(std::pair<EntityID, EntityID>(newEntity, parent));
+	return newEntity;
+}
+
+World::~World()
+{
+
+}
+
+World::World()
+{
+	m_LastEntityID = 0;
+}
+
+void World::Initialize()
+{
+	RegisterSystems();
+	AddSystems();
+	for (auto system : m_Systems) {
+		system.second->Initialize();
+	}
+
+	RegisterComponents();
+}
+
+std::shared_ptr<Component> World::AddComponent(EntityID entity, std::string componentType)
+{
+	return AddComponent<Component>(entity, componentType);
+}
+
+void World::AddSystem(std::string systemType)
+{
+	m_Systems[systemType] = std::shared_ptr<System>(m_SystemFactory.Create(systemType));
+}