8 replies to this topic

[Kylo]

I'm sorry, I'm a noob with SDL, but I'm having trouble just getting it to compile. But the thing is, the very first SDL project I ever made worked perfectly, and after following the same exact steps with my next one, ever since then I have had absolutely no success. Let me start from the beginning.

I used the tutorials at lazyfoo.net to set up SDL with VC++ 2008. My first project, as I said, worked fine. Afterwards, it kept saying I had no entry point. I think this means it can't find main() anywhere, but I have a main() function. I've made several other projects, all with the same issue, VC cannot find an entry point. So I right clicked main and went to its definition, and it turns out SDL has a #define for main to turn it into SDLMain. I'm guessing the real main has been hidden in the library because I can't find any source for it.

So then I tried MinGW. Again, one successful project, then it all crumbles. I will add that for some reason the source files I got from LF work perfectly, but mine give me a different error, that main() is making an undefined reference to 'WinMain@16' and then collect2 returns an exit status 1.

Tried with Bloodshed Dev C++, see MinGW story.

Code::Blocks, can't find main().

Can someone give me some detailed instructions or a link to them that may help point out what I'm doing wrong? I swear I followed LF's instructions to the letter, and I keep my VC and MinGW versions of SDL in separate directories. I am rather desperate to learn SDL. From what I've seen of it, it's the best C++ library I've seen, and I feel so comfortable with how it works. I've tried several other devkits, and this one really strikes a good cord with me, so please, if anyone can help, I would be forever grateful.

[Flying Dutchman]

Can you please provide the code that doesn't compile.

As a guess though, I'd say you used the lazy main definition:

// lazy one
int main() {

}

// one that SDL wants
int main(int argc, char* argv[]) {

}

[Alexander]

The WinMain@ issue is likely the toolchain not being able to determine where the entry point of the application is.

If you set up a main() signature that SDL's library/macros recognise (as FlyingDutchman has pointed out) then you can in MinGW link it with -lmingw32 -lSDLmain -lSDL and any other libraries you required to compile it.

I will attempt to make a proof of concept on my Windows XP machine tomorrow (I believe I have done it a few times in the past) when I wake up if you have no luck causing it to work.

Alexander.

Edited by Alexander, 05 December 2011 - 03:40 AM.

[Kylo]

This is my code:

//Include

#include "SDL.h"

#include "SDL_image.h"

#include <string>


//Declarations

#define SCREEN_W 320

#define SCREEN_H 240

#define SCREEN_B 32

#define APP_NAME "SDL"


typedef SDL_Surface img;

typedef SDL_Rect Rec;


img* screen;

img* hello;

SDL_Event* Event;


//Prototypes

bool init();

void drawImage(int x, int y, SDL_Surface* source, SDL_Surface* destination);

img* loadImage(std::string filename);


int main( int argc, char* args[] )

{


    //Start SDL

    SDL_Init( SDL_INIT_EVERYTHING );


	//Set up the screen

	screen = SDL_SetVideoMode(SCREEN_W, SCREEN_H, SCREEN_B, SDL_SWSURFACE);


	//Load image

	hello = loadImage("red_strip36.bmp");


	//Draw image

	SDL_BlitSurface(hello, 0, screen, 0);


	//Refresh screen

	SDL_Flip(screen);


	//Pause

	SDL_Delay(2000);


	//Free surface

	SDL_FreeSurface(hello);

    

    //Quit SDL

    SDL_Quit();

    

    return 0;    

};


///////////////////

//OTHER FUNCTIONS//

///////////////////


bool init(){

    //Initialize all SDL subsystems

    if( SDL_Init( SDL_INIT_EVERYTHING ) == -1 )

    {

        return false;    

    }

    

    //Set up the screen

    screen = SDL_SetVideoMode( SCREEN_W, SCREEN_H, SCREEN_B, SDL_SWSURFACE );

    

    //If there was an error in setting up the screen

    if( screen == NULL )

    {

        return false;    

    }

    

    //Set the window caption

    SDL_WM_SetCaption(APP_NAME, NULL);

    

    //If everything initialized fine

    return true;

};


void drawImage( int x, int y, SDL_Surface* source, SDL_Surface* destination ){

    //Temporary rectangle to hold the offsets

    Rec offset;

    

    //Get the offsets

    offset.x = x;

    offset.y = y;

    

    //Blit the surface

    SDL_BlitSurface( source, NULL, destination, &offset );

};


img* loadImage( std::string filename ){

    //The image that's loaded

    img* loadedImage = NULL;

    

    //The optimized image that will be used

    img* optimizedImage = NULL;

    

    //Load the image

    loadedImage = IMG_Load( filename.c_str() );

    

    //If the image loaded

    if( loadedImage != NULL )

    {

        //Create an optimized image

        optimizedImage = SDL_DisplayFormat( loadedImage );

        

        //Free the old image

        SDL_FreeSurface( loadedImage );

    }

    

    //Return the optimized image

    return optimizedImage;

};

I copy this into a new project, it fails. But the first time it worked.

[Alexander]

I had:

• Installed SDL development libraries (for mingw) and SDL_image development libraries(for VC) in to C:\mingw
  
• Had moved the contents of the C:\mingw\includes\sdl folder to C:\mingw\includes so that it could be read properly
  
• Had placed SDL_image.dll from the development library package in to C:\Windows as it wouldn't run without it (runtime)
  
• Compiled with this line:

g++ -Wall -o foo.exe foo.cxx -lmingw32 -lSDLmain -lSDL -lSDL_image

It seemed to run fine afterwards. I am not sure the MSVC setup would be too difficult if you wish to go that route, after you set up how I have.

Alexander.

[Kylo]

Alexander said:

I had:

• Installed SDL development libraries (for mingw) and SDL_image development libraries(for VC) in to C:\mingw
  
• Had moved the contents of the C:\mingw\includes\sdl folder to C:\mingw\includes so that it could be read properly
  
• Had placed SDL_image.dll from the development library package in to C:\Windows as it wouldn't run without it (runtime)
  
• Compiled with this line:

g++ -Wall -o foo.exe foo.cxx -lmingw32 -lSDLmain -lSDL -lSDL_image

It seemed to run fine afterwards. I am not sure the MSVC setup would be too difficult if you wish to go that route, after you set up how I have.Alexander.

I'm sorry, I don't understand this post.I have all my DLLs in the exe directory, but I don't see how that shouod effect compiling, and I made sure the header directories matched.What does that -Wall argument do?

[Flying Dutchman]

-Wall shows all warnings.

I've copied your code and it works fine, even after several compiles.

[Kylo]

Flying Dutchman said:

-Wall shows all warnings.

I've copied your code and it works fine, even after several compiles.

I know the code works. It's the projects that don't. I got each compiler to work ONCE, and then never again. I have one project that I can compile, but when I follow the exact setup instructions by the letter, making a carbon copy of the project, it fails. The code isn't the problem. It's the projects. Or maybe it's just me. I can't think of anything. I've looked at every single aspect of this thing, checked and rechecked and rerere-freaking-REchecked that everything was exactly the same, and still, only the one will compile. I am at a loss.

[Flying Dutchman]

Try to reinstall the IDE. If that doesn't work, try to compile it manually - if you haven't already.