White texture showing in place of actual texture when not using dynamic memory in SFML

Question

I have an Armor class that stores a texture and a sprite to be drawn to the screen like such:

Armor.h

class Armor 
{
public:
    Armor(const std::string& armorName);

    void draw(sf::RenderWindow& window);

    ~Armor();

private:
    sf::Texture armorTexture;
    sf::Sprite armorSprite;
    int numOfArmor;
};

Armor.cpp

#include "Armor.h"
Armor::Armor(const std::string& armorName)
{
    armorTexture.loadFromFile(armorName);
    armorSprite.setTexture(armorTexture);
    numOfArmor = 0;
}


void Armor::draw(sf::RenderWindow& window)
{
    window.draw(armorSprite);
}

Armor::~Armor()
{
}

I also have an object called Application which stores an instance of Armor in a map, like such:

Application.h

class Application
{
public:
    Application();

    void start();

    ~Application();
private:
    sf::RenderWindow window;
    std::map<std::string, Armor> armorMap;
    std::map<std::string, Armor>::iterator armorIter;

};

Application.cpp

#include "Application.h"

Application::Application()
{
    window.create(sf::VideoMode(640, 480), "SFML Application", sf::Style::Close);
    window.setFramerateLimit(120);

    std::string armorName;
    std::ifstream file("Armors.txt");
    while (file >> armorName)
        armorMap.emplace(armorName, Armor(armorName + "Armor.png"));
    file.close();

    armorIter = armorMap.begin();
}

void Application::start()
{
    while (window.isOpen())
    {

        sf::Event evnt;
        while (window.pollEvent(evnt))
        {

            if (evnt.type == sf::Event::Closed)
                window.close();
        }

        window.clear();
        while (armorIter != armorMap.end())
        {
            armorIter->second.draw(window);
            armorIter++;
        }
        armorIter = armorMap.begin();
        window.display();
    }
}

Application::~Application()
{
}

Whenever I construct the object, a white texture appears on the screen, which as I've found out is known as the white texture problem. I was stumped because I'm sure my texture wasn't getting destroyed, so I decided instead to change the map to std::map<std::string, Armor*> armorMap and this fixed all my issues! Why would storing a pointer to an object of type Armor in the map work, but not the way I initially did it?

Answer 1

When you store your armour object into the map you are making a copy of it, its texture and its sprite.

The sprite has stored your texture as a pointer to the original texture object which was destroyed (see https://www.sfml-dev.org/documentation/2.5.0/classsf_1_1Sprite.php#a3729c88d88ac38c19317c18e87242560).

Storing pointers in the map will give you much better performance anyway as you will avoid the unnecessary texture copies. You should probably be using std::shared_ptr<Armour> rather than raw pointers unless you really know what you are doing.