SFML community forums

Help => General => Topic started by: GamerH2 on October 12, 2017, 02:45:58 am

Title: Crash after too many objects in screen
Post by: GamerH2 on October 12, 2017, 02:45:58 am

My game crashes after my objects vector's size gets higher than 127.

This is my code

--- Main loop function

Code: [Select]

// Set the FPS limit of the window
m_window.setFramerateLimit(60);

// Activate the window
m_window.setActive(true);

// Disable lighting
glDisable(GL_LIGHTING);

// Configure the viewport (the same size as the window)
glViewport(0, 0, m_window.getSize().x, m_window.getSize().y);

// Enable OpenGL
glEnable(GL_TEXTURE_2D);

// Load all scenes
SceneTest sc_0;
scenes.push_back(&sc_0);

sf::Texture sortOfATex;
sortOfATex.loadFromFile("data/uglie.gif");

// Main game loop
while (m_window.isOpen())
{
// Event
sf::Event event;

while (m_window.pollEvent(event))
{
// Close the game when the [X] button is clicked
if (event.type == sf::Event::Closed)
m_window.close();
}

// Clear the buffers
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// Run the scene
scenes[currentScene]->run(m_window);

if (sf::Keyboard::isKeyPressed(sf::Keyboard::B))
{
GameObject obj(sortOfATex);
objects.push_back(obj);
}

int8_t i;

for (const auto& x : objects)
{
objects[i].update();
objects[i].draw(m_window);
i++;
}

i = 0;

// Display the things on the window
m_window.display();

}
--- GameObject
Source file

Code: [Select]

#include "GameObject.hpp"

GameObject::GameObject(sf::Texture& text)
    : spr(text)
{}

GameObject::~GameObject() {}

void GameObject::update()
{
    spr.move(1, 0);
}

void GameObject::draw(sf::RenderWindow& w)
{
    w.draw(this->spr);
}
Header

Code: [Select]

#ifndef GAMEOBJECT_HPP
#define GAMEOBJECT_HPP
#include <SFML/Graphics.hpp>

class GameObject
{
    public:
        GameObject(sf::Texture& text);
        virtual ~GameObject();
        virtual void    update();
        virtual void    draw(sf::RenderWindow& w);
    private:
        sf::Sprite      spr;
};

#endif // GAMEOBJECT_HPP

Thanks for reading.

Title: Re: Crash after too many objects in screen
Post by: eXpl0it3r on October 12, 2017, 07:39:32 am

And what's the call stack?

Title: Re: Crash after too many objects in screen
Post by: GamerH2 on October 12, 2017, 12:42:19 pm

Do you mean that's happening stack overflow?
Then, how i can fix it? Because the game crashes after the first object when i do this:

Code: [Select]

std::vector<GameObject*> objects;

if (sf::Keyboard::isKeyPressed(sf::Keyboard::B))
{
    GameObject* obj = new GameObject(sortOfATex);
    objects.push_back(obj);
    delete obj;
}

int8_t i;

for (const auto& x : objects)
{
objects[i]->update();
objects[i]->draw(m_window);
i++;
}

i = 0;



Title: Re: Crash after too many objects in screen
Post by: Rhimlock on October 12, 2017, 12:49:51 pm

Do you have any references or pointers to elements of your vector?

When you add an element to your vector and it reaches a size larger than n², it resizes and might get moved to an other space in memory, invalidating your previous pointer.

Title: Re: Crash after too many objects in screen
Post by: Laurent on October 12, 2017, 12:51:49 pm

Quote

Do you mean that's happening stack overflow?

When your code crashes, you usually run it with the debugger, which gives you plenty of information about the error. Among them, one of the most useful is the call stack, which is the sequence of function calls that led to the location of the crash. Knowing what crashed and at which location in source code, is a very good starting point for debugging a crash ;)

Quote

the game crashes after the first object when i do this

You delete the object that you just added to your vector, then you try to use it. Accessing a deleted memory location is undefined behaviour.

Title: Re: Crash after too many objects in screen
Post by: GamerH2 on October 12, 2017, 01:01:47 pm

I ran the debugger, and after the crash, this appear in the debugger

Code: [Select]

Program received signal SIGSEGV, Segmentation fault.
At Core.cpp:73

Core.cpp:73 is the  objects.update();

Title: Re: Crash after too many objects in screen
Post by: GamerH2 on October 12, 2017, 01:16:32 pm

I found what's happening!

Code: [Select]

int8_t i;

for (const auto& x : objects)
{
objects[i].update();
objects[i].draw(m_window);
i++;
}

i = 0;

I declared a signed int8_t variable, which explains why the object limit was being 127!!!
So, i changed it to a unsigned short, and now i can have 65535 objects in screen.

Thanks for the help guys!

Title: Re: Crash after too many objects in screen
Post by: Laurent on October 12, 2017, 02:18:20 pm

That's a very complicated and unintuitive way to iterate on your object array.

for (const auto& x : objects)
{
    x.update();
    x.draw(m_window);
}

No more limit.