"Basic" entity component system. Almost.

Escape-the-Dawn/World.h

@@ -0,0 +1,81 @@
+#include <stack>
+#include <unordered_map>
+#include <vector>
+#include <string>
+
+#include "Entity.h"
+#include "Component.h"
+#include "Components/Transform.h"
+
+class World
+{
+public:
+	World()
+	{
+		m_LastEntityID = 0;
+	}
+
+	EntityID CreateEntity(EntityID parent = 0)
+	{
+		EntityID newEntity = GenerateEntityID();
+		m_SceneGraph.insert(std::pair<EntityID, EntityID>(newEntity, parent));
+		return newEntity;
+	}
+
+	void RemoveEntity(EntityID entity)
+	{
+		m_SceneGraph.erase(entity);
+		RecycleEntityID(entity);
+	}
+
+	bool ValidEntity(EntityID entity)
+	{
+		return m_SceneGraph.find(entity) != m_SceneGraph.end();
+	}
+
+	EntityID GetEntityParent(EntityID entity)
+	{
+		auto it = m_SceneGraph.find(entity);
+		return it == m_SceneGraph.end() ? 0 : it->second;
+	}
+
+	std::shared_ptr<Component> AddComponent(EntityID entity, std::string componentType)
+	{
+		std::shared_ptr<Component> component = ComponentFactory::Instance()->Create(componentType);
+		m_ComponentsOfType[componentType].push_back(component);
+		m_EntityComponents[entity][componentType] = component;
+	}
+
+	/*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;
+	}*/
+
+private:
+	EntityID m_LastEntityID;
+	std::stack<EntityID> m_RecycledEntityIDs;
+	// A map of child entities to parent entities
+	std::unordered_map<EntityID, EntityID> m_SceneGraph; 
+	std::unordered_map<std::string, std::vector<std::shared_ptr<Component>>> m_ComponentsOfType;
+	std::unordered_map<EntityID, std::map<std::string, std::shared_ptr<Component>>> m_EntityComponents;
+
+	EntityID GenerateEntityID()
+	{
+		if (!m_RecycledEntityIDs.empty()) {
+			EntityID id = m_RecycledEntityIDs.top();
+			m_RecycledEntityIDs.pop();
+			return id;
+		} else {
+			return ++m_LastEntityID;
+		}
+	}
+
+	void RecycleEntityID(EntityID id)
+	{
+		m_RecycledEntityIDs.push(id);
+	}
+};