C++如何实现一个简单的实体组件系统(ECS)_C++游戏架构设计与ECS实现

using Entity = uint32_t;
constexpr size_t MAX_ENTITIES = 10000;

struct Position {
    float x, y;
};

struct Velocity {
    float dx, dy;
};

struct Health {
    int value;
};

template
class ComponentArray {
    std::array data;
    std::array exists{};
public:
    void insert(Entity entity, T component) {
        data[entity] = component;
        exists[entity] = true;
    }

    void remove(Entity entity) {
        exists[entity] = false;
    }

    T& get(Entity entity) {
        return data[entity];
    }

    bool has(Entity entity) {
        return exists[entity];
    }
};

class EntityManager {
    std::queue available;
    std::bitset alive;

public:
    EntityManager() {
        for (Entity i = 0; i < MAX_ENTITIES; ++i)
            available.push(i);
    }

    Entity create() {
        Entity id = available.front();
        available.pop();
        alive.set(id);
        return id;
    }

    void destroy(Entity entity) {
        alive.reset(entity);
        available.push(entity);
    }

    bool isAlive(Entity entity) {
        return alive[entity];
    }
};

class ComponentManager {
    std::unordered_map> components;

public:
    template
    void registerComponent() {
        components[std::type_index(typeid(T)).hash_code()] = 
            std::make_shared>();
    }

    template
    void addComponent(Entity entity, T component) {
        auto ptr = std::static_pointer_cast>(
            components[std::type_index(typeid(T)).hash_code()]
        );
        ptr->insert(entity, component);
    }

    template
    T& getComponent(Entity entity) {
        auto ptr = std::static_pointer_cast>(
            components[std::type_index(typeid(T)).hash_code()]
        );
        return ptr->get(entity);
    }

    template
    bool hasComponent(Entity entity) {
        auto ptr = std::static_pointer_cast>(
            components[std::type_index(typeid(T)).hash_code()]
        );
        return ptr->has(entity);
    }
};

class MovementSystem {
public:
    void update(ComponentManager& cm) {
        for (Entity e = 0; e < MAX_ENTITIES; ++e) {
            if (cm.hasComponent(e) && cm.hasComponent(e)) {
                auto& pos = cm.getComponent(e);
                auto& vel = cm.getComponent(e);
                pos.x += vel.dx;
                pos.y += vel.dy;
            }
        }
    }
};