Question

我正在学习 SDL，并正在尝试创建一个 GameObject 类，该类将成为我游戏中所有对象的基类。

这是头文件：

#pragma once

#include <stdio.h>
#include "Game.h"
#include "TextureManager.h"

class GameObject 
{
public:
    void load(int x, int y, int w, int h, std::string texture_id);
    void draw(SDL_Renderer* renderer);
    void update();
    void clean() { printf("clean function.\n"); }
protected:
    std::string texture_id;
    int x;
    int y;
    int width;
    int height;
    int current_row;
    int current_frame;
};

这是代码文件：

#include "GameObject.h"

void GameObject::load(int x, int y, int w, int h, std::string texture_id)
{
    this->x = x;
    this->y = y;
    this->width = w;
    this->height = h;
    this->texture_id = texture_id;
    this->current_row = 1;
    this->current_frame = 1;
}

void GameObject::draw(SDL_Renderer *renderer)
{
    TheTextureManager::Instance()->draw_frame(this->texture_id,
                                              this->x, this->y, this->width, this->height,
                                              this->current_row, this->current_frame, renderer);
}

void GameObject::update()
{
    this->x += 1;
}

我正在尝试在 GameObject 类的私有部分创建 Player 类和 Game（子类）的对象，以便使用 GameObject 函数（用于例如GameObject :: draw ()）。有代码：

#pragma once

#include <string>
#include <SDL2/SDL.h>
#include "GameObject.h"
#include "Player.h"

class Game
{
private:
    SDL_Renderer* renderer;
    SDL_Window* window;
    GameObject game_object;
    Player player;

    bool running;
public:
    Game() {}
    ~Game() {}

    void init(std::string name, int x, int y, int width, int height, int flags = 0);
    void update();
    void handle_events();
    void draw();
    void clear();
    bool is_running() { return running; }
};

但是当我声明这些行时，我收到以下错误：

g++ -std=c++11 -Wall -g -o obj/Game.o -c src/include/Game.cpp

g++ -std=c++11 -Wall -g -o obj/Player.o -c src/include/Player.cpp

In file included from src/include/GameObject.h:4,
                 from src/include/Player.h:3,
                 from src/include/Player.cpp:1:

src/include/Game.h:13:5: error: ‘GameObject’ does not name a type
   13 |     GameObject game_object;
      |     ^~~~~~~~~~
src/include/Game.h:14:5: error: ‘Player’ does not name a type
   14 |     Player player;
      |     ^~~~~~
make: *** [Makefile:47: obj/Player.o] Error 1

我使用 Makefile 实用程序来构建项目。请告诉我我的错误在哪里？为什么我不能创建和使用类对象？

附言这是 Player 类：

标题。

#pragma once

#include "GameObject.h"

class Player : public GameObject
{
public:
    void load(int x, int y, int w, int h, std::string texture_id);
    void draw(SDL_Renderer* renderer);
    void update();
    void clean() { GameObject::clean(); printf("clean a player.\n"); }
};

身体。

#include "Player.h"

void Player::load(int x, int y, int w, int h, std::string texture_id)
{
    GameObject::load(x, y, w, h, texture_id);
}

void Player::draw(SDL_Renderer* renderer)
{
    GameObject::draw(renderer);
}

void Player::update()
{
    this->y += 1;
    this->x -= 1;
}

为什么我不能创建类的对象？

0 个答案: