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C++ & SFML?

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I'm new to C++ and I wanted to try SFML.

 

So I downloaded visual studio 2012 and the SFML 2.1 zip file. Extracted it to C:/sfml2.1

 

And I followed the instructions. I also disabled the 'Precompiled header' option in  'configuration -> C/C++ -> Precompiled headers' as suggested by another thread here on gamedev.

 

But I'm getting this error:

The program can't start because sfml-system-d-2.dll is missing from your computer. Try reinstall...

Any ideas?

 

Thanks in advance!

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You are welcome. Glad I could help. I think there is mention somewhere on the site about the DLLs.

By the way, from the Visual Studio tutorial page:

 

 

Now compile the project, and if you linked to the dynamic version of SFML, don't forget to copy the SFML DLLs (they are in <sfml-install-path/bin>) to the directory where your compiled executable is. Then run it, and if everything is ok you should see this:
Edited by Dragonsoulj

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Or just add the bin directory of SFML to the path, then you dont need to copy the dll files every time you make a new project. Just remember users of your program need them.

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You can get SFML liked statically to remove the need for dll. Static linking reduces the final size of the program, but possibly makes updates bigger.

I use static linking for convenience.

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I see. I did some stuff with the words 'linking' and 'sfml_static' I dno if that was linking.

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I have a question. What's going on in the Dog::Dog() constructor there?

Class Dog {
    private:
        Pig pig;
        Cat cat;
}

Dog::Dog()
    : pig(1)
    , cat()
{
}

Coming from other OOP languages, I find this strange tongue.png

Edited by afflicto

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I have another question. in SFML there is a templated Vector2 class.

 

I've been trying to extend it for the past few hours but damn...

 

Here's my code:

#pragma once
#include <SFML/Graphics.hpp>
#include <cmath>

template <typename T>
class Vector2 : sf::Vector2 {

public:
	T mag();
	void normalize();
	void invert();
	void decrease(T i);
	void reset();
	void limit(int i);
};

template <typename T>
T Vector2<T>::mag() {
	return sqrt(this->x*2 + this->y*2);
}
Edited by afflicto

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I would not do it that way. By deriving from that class that is not much more than a struct with a constructor, you are overcomplicating this and you will have to copy the vectors you get from sfml into your new type before you can use those methods. You better just make some free functions in the same way most of the functionality for using sf::Vector2 is done.

Though you should think again before doing that, the SFML vectors are just a tiny thing for communicating with that library and you may be much better off with using a real vector/matrix library like GLM: http://glm.g-truc.net

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I run into another issue.

 

I have a class 'Game'. and when instantiated, I want to store the instance on a static member of the 'Game' class but some code in SFML complains about NonCopyable.

 

I tried storing a reference, reference to a pointer and a the dereferenced object to no avail.

 

Here's the class:

class Game
{
	private:
		sf::RenderWindow mWindow;
		
	protected:
		std::vector<Entity> entities;

	public:
		static Game instance;
}

and the implementation:

Game::Game()
	: mWindow(sf::VideoMode(640, 480), "SFML!")
{
	//set the game instance
	Game::instance = *this;
}

Here's the full error:

error C2248: 'sf::NonCopyable::operator =' : cannot access private member declared in class 'sf::NonCopyable'	c:\sfml2.1\include\sfml\window\window.hpp	477	1	sfmltest2

What's going on here?

Edited by afflicto

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That means you should not do that with the RenderWindow as it was intentionally made not copyable to prevent errors.

Also singletons should be avoided as much as possible. Just create your objects somewhere and only pass a reference to as little functions through their arguments as possible and needed, to not get into the trap of creating spaghetti code.

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I was able to make it work.

 

It's not exactly a singleton. I just need my input object, sound object, gui object etc to access each other.

 

I think passing things around all the time is more like spaghetti code than to have 1 single place to store a reference to something. Less typing as well.

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If you want to have a private variable that stores the window, change it to a pointer and create a window with new:

 

In declaration:

sf::RenderWindow * mWindow;

 

In constructor:

mWindow = new sf::RenderWindow(sf::VideoMode(640, 480), "SFML!");

 

In destructor:

delete mWindow;

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It's not exactly a singleton. I just need my input object, sound object, gui object etc to access each other.

Which works fine if you pass references between things or have a container object to access them, if code was "just better" to have everything public and visible to each other we wouldn't have access modifiers at all.

I think passing things around all the time is more like spaghetti code than to have 1 single place to store a reference to something. Less typing as well.

I could argue against this but frankly there's at least a couple hundred live or half-dead threads on these forums going over this topic so I'm not going to bother, needless to say most people here are going to suggest you not just make everything global, public, or a singleton just because you think it makes it easier to type/deal with.

Hint: It doesn't. Definitely not in the long term.

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I was able to make it work.

 

It's not exactly a singleton. I just need my input object, sound object, gui object etc to access each other.

 

I think passing things around all the time is more like spaghetti code than to have 1 single place to store a reference to something. Less typing as well.

 

There is a lot of hidden dangers with using globally accessible variables. For one thing, it's hard to keep track of all the points of access. Because the objects can be accessed at any time, there is little options for the code to tell you that you need to initialize some global variable before the code can work correctly. At some point you'll forget that one of the classes in your code depends on a global variable and you'll forget to initialize it. Now you're wasting time fixing something that could have been prevented had you declared it as an input argument in your constructor. Sure, you can declare everything global, but you should keep in mind that scoping and proper class interfaces are there to tell you what information you need and hide information that should not be accessed elsewhere. It limits how many things you'll have to focus on and will keep you from creating functions that have hidden side effects.

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