朋友课程和标题文件

Question

我正在编写一个C ++程序，我希望在其中使用朋友类来访问其他类的受保护成员。 Here is the header for the class I wish to access:

#pragma once

#include <vector>

#include "../glm/glm.hpp"

// An enum class and some structs here

class Polygon {
public:
    // Constructors, destructor...
    Polygon();
    Polygon(int n_vertices, int n_indices);
    Polygon(int n_vertices, int n_indices, float* vertices, unsigned int* indices);
    ~Polygon();
    
    // Loads of other irrelevant functions go here
    
protected:
    // Bunches of other ivars before these
    unsigned int lastVBO;
    unsigned int lastVAO;
    unsigned int lastIBO;
    
    friend class Renderer;
};

And here is the declaration of the class which I wish to be its friend:

#include <string>
#include <iostream>
#include <vector>

#include "../geometry/polygon.hpp"
#include "../geometry/rectangle.hpp"
#include "../geometry/circle.hpp"

class Renderer {
public:
    Renderer();
    ~Renderer();
    void queuePolygon(Polygon* p);
    void drawPolygons();
private:
    // Rectangle and Circle are children of Polygon
    // Which one of these gets called is determined in queuePolygon/drawPolygon
    void queueRectangle(Rectangle* r);
    void queueCircle(Circle* c);
    void drawRectangle(Rectangle* r);
    void drawCircle(Circle* c);
    
    std::vector<Rectangle*>* rectangleQueue;
    std::vector<Circle*>* circleQueue;
};

Now obviously what I want is to get access to the protected members IBO, VBO and VAO from the Polygon class ，为了使用我的渲染器绘制多边形。然而，通过这种实现，即使在多边形课程中的朋友声明中，我也无法访问这些伊瓦尔人。在polygon.hpp中导入渲染器标头会破坏整个内容，因为子类不再表现得很好。

有人以前遇到过这个问题吗？您能告诉我我在做什么错吗？