example.cpp

#include "entity/World.hpp"
#include <iostream>
using namespace entity;

struct PositionComponent
{
  PositionComponent(int x = 0, int y = 0) : x(x), y(y) {}
  int x, y;
};

struct VelocityComponent
{
  VelocityComponent(int dx = 0, int dy = 0) : dx(dx), dy(dy) {}
  int dx, dy;
};

class MoveSystem : public System
{
public:
  MoveSystem()
  {
    RequireComponent<PositionComponent>();
    RequireComponent<VelocityComponent>();
  }

  void Update()
  {
    for (auto e : GetEntities())
    {
      auto &position = e.GetComponent<PositionComponent>();
      const auto velocity = e.GetComponent<VelocityComponent>();
      position.x += velocity.dx;
      position.y += velocity.dy;
    }
  }
};

int main()
{
  World world;
  auto e = world.CreateEntity();
  e.AddComponent<PositionComponent>(100, 100);
  e.AddComponent<VelocityComponent>(10, 10);
  world.GetSystemManager().AddSystem<MoveSystem>();

  for (int i = 0; i < 10; i++)
  {
    world.Update();
    world.GetSystemManager().GetSystem<MoveSystem>().Update();
    auto &position = e.GetComponent<PositionComponent>();
    std::cout << "x: " << position.x << ", y: " << position.y << std::endl;
  }

  return 0;
}