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Help => Graphics => Topic started by: codeed on December 11, 2010, 07:31:52 pm

Title: Visual C++ 2008: sf::Image as static attribute
Post by: codeed on December 11, 2010, 07:31:52 pm

Hi all,

I have problems using sf::Image as static attributes. I've created an empty cmd console Project with Visual C++ 2008 and added the Missile Class from this Tutorial:

http://www.sfml-dev.org/tutorials/1.6/graphics-sprite.php

If I add now a new missile object i get error LNK2020 and error LNK2001.
When i remove the keyword static it works fine.

I've linked all required libs in the project settings and included the Graphics.hpp in the standard header file (stdafx.h).

Main.cpp

Code: [Select]


// Main.cpp: Hauptprojektdatei.

#include "stdafx.h"
#include "Missile.h"

using namespace System;

int main(array<System::String ^> ^args)
{
     Missile missile;

    return 0;
}



Missile.h

Code: [Select]


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

class Missile
{
public :

    static bool Init(const std::string& ImageFile)
    {
        return Image.LoadFromFile(ImageFile);
    }

    Missile()
    {
        Sprite.SetImage(Image); // every sprite uses the same unique image
    }

private :

    static sf::Image Image; // shared by every instance

    sf::Sprite Sprite; // one per instance
};



Missile.cpp

Code: [Select]


#include "StdAfx.h"
#include "Missile.h"


I hope you can help me.

Regards Paul

Title: Visual C++ 2008: sf::Image as static attribute
Post by: Nexus on December 11, 2010, 08:15:35 pm

You posted in the wrong subforum, this has nothing to do with the C binding of SFML.

You must define static variables outside the class (in the .cpp file):

Code: [Select]

sf::Image Missile::Image;

But your code is a little bit strange. First,

Code: [Select]

int main(array<System::String ^> ^args)isn't C++, rather C++/CLI. If you don't need this language crucially for .NET interop, you'd better avoid it. The other thing is

Code: [Select]

#include "Missile.h" inside the header "Missile.h", which makes no sense.

Title: Visual C++ 2008: sf::Image as static attribute
Post by: codeed on December 11, 2010, 09:15:15 pm

Hi Nexus,

thanks for your fast reply. But I don't know how moving the static variable outside of the class definition should solve the problem. I want it to be an attribute of the class.

Anyway I tried your suggestion and put the Image variable above the class.

Now if I start the programme it spits out random letters and numbers and crashes after a few seconds.  


PS: I mixed up the file names in my first post the .h file is in fact the .cpp file

Title: Visual C++ 2008: sf::Image as static attribute
Post by: Nexus on December 11, 2010, 09:44:30 pm

Quote from: "codeed"

But I don't know how moving the static variable outside of the class definition should solve the problem. I want it to be an attribute of the class.

Only the definition has to be outside the class. The declaration of the static variable is still inside.

Quote from: "codeed"

Now if I start the programme it spits out random letters and numbers and crashes after a few seconds.

Did you link the correct libraries (consistent debug/release configuration)? If yes, could you be a bit more specific about your problem? Maybe a minimal, complete code that represents the issue?

Title: Visual C++ 2008: sf::Image as static attribute
Post by: codeed on December 12, 2010, 02:45:01 am

Now I get it. Also I've linked the wrong graphics lib :oops:.

Thanks for your help !