[게임 프로그래밍 패턴] 13. 컴포넌트 패턴

한 개체가 여러 분야를 서로 커플링없이 다룰 수 있게 한다.

#include <iostream>

using namespace std;

class GameObject {
public:
	int velocity;
	int x, y;

	GameObject(InputComponent* input, PhsicsComponent* phsics, GraphicsComponent* graphics) 
		: input_(input), phsics_(phsics), graphics_(graphics) {}

	void update(World& world, Graphic& graphics) {
		input_->update(*this);

		//속도에 따라 위치를 바꾼다.
		phsics_->update(*this, world);

		//알맞은 스프라이트를 그린다.
		graphics_->update(*this, graphics);
	}

private:
	InputComponent* input_;
	PhsicsComponent* phsics_;
	GraphicsComponent* graphics_;
};

class InputComponent {
public:
	virtual ~InputComponent() {}
	virtual void update(GameObject& gameObj) = 0;
};

class BjornInputComponent : public InputComponent {
public:
	virtual void update(GameObject& bjorn) {
		switch (Controller::getJoystickDirection())
		{
		case DIR_LEFT:
			bjorn.velocity -= WALK_ACCELERATION;
			break;
		case DIR_RIGHT:
			bjorn.velocity += WALK_ACCELERATION;
			break;
		}
	}
private:
	static const int WALK_ACCELERATION = 1;
};

class DemoInputComponent : public InputComponent {
public:
	virtual void update(GameObject& gameObj) {
		// AI가 알아서 Bjorn을 조정한다...
	}
};

class PhsicsComponent {
public:
	virtual ~PhsicsComponent() {}
	virtual void update(GameObject& gameObj, World& world) = 0;
};

class BjornPhsicsComponent : public PhsicsComponent{
public:
	virtual void update(GameObject& bjorn, World& world) {
		bjorn.x += bjorn.velocity;
		world.resolveCollision(volume_, bjorn.x, bjorn.y, bjorn.velocity);
	}

private:
	Volume volume_;
};

class GraphicsComponent{
public:
	virtual ~GraphicsComponent() {}
	virtual void update(GameObject& gameObj, Graphics& graphics) = 0;
};

class BjornGraphicsComponent : public GraphicsComponent{
public:
	virtual void update(GameObject& bjorn, Graphics& graphics) {
		Sprite* sprite = &spriteStand_;
		if (bjorn.velocity < 0) {
			sprite = &spriteWalkLeft_;
		}
		else if (bjorn.velocity > 0) {
			sprite = &spriteWalkRight_;
		}
		graphics.draw(*sprite, bjorn.x, bjorn.y);
	}
private:
	Sprite spriteStand_;
	Sprite spriteWalkLeft_;
	Sprite spriteWalkRight_;
};

int main() {
	GameObject* gameObj = new GameObject(new BjornInputComponent(), new BjornPhsicsComponent(), new BjornGraphicsComponent());
}