Weird SDL_Surface->format->BytesPerPixel value

Question

So I'm using SDL_image to load heightmap and create terrain in my OpenGL app.

That's how I initialize SDL_image:

int flags = IMG_INIT_PNG;
int initted = IMG_Init(flags);
if((initted & flags) != flags) {
    printf("IMG_Init: Failed to init required jpg and png support!\n");
    printf("IMG_Init: %s\n", IMG_GetError());
    return;
}

Load(filename);

...And this is my Load function:

void Load(string filename) {
    img = IMG_Load(filename.c_str());
    if(!img) {
        printf("IMG_Load: %s\n", IMG_GetError());
        return;
    }
    printf("IMG_Load: %s\n", IMG_GetError());
    xsize = img->w;
    ysize = img->h;

    SDL_LockSurface(img);
    imgData = (Uint32*)img->pixels;
    SDL_UnlockSurface(img);
}

Then, in my Terrain class where I'm preparing my vertex buffer I'm reading pixel values with this method:

Uint32 getPixel(int x, int y) {
    SDL_LockSurface(img);

    int bpp = img->format->BytesPerPixel;
    //cout << "bpp " << bpp << "\n";
    /* Here p is the address to the pixel we want to retrieve */
    Uint8 *p = (Uint8 *)img->pixels + y * img->pitch + x * bpp;

    SDL_UnlockSurface(img);

    switch(bpp) {
    case 1:
        return *p;
        break;

    case 2:
        return *(Uint16 *)p;
        break;

    case 3:
        if(SDL_BYTEORDER == SDL_BIG_ENDIAN)
            return p[0] << 16 | p[1] << 8 | p[2];
        else
            return p[0] | p[1] << 8 | p[2] << 16;
        break;

    case 4:
        return *(Uint32 *)p;
        break;

    default:
        return 0;       /* shouldn't happen, but avoids warnings */
    }
}

...and it turns out that every time I run the program img->format->BytesPerPixel returns a random value... What the heck? Does anyone have any idea? This should only return 1, 2, 3 or 4.

Answer 1

OK, I was just being stupid... But if anyone ever has a problem like me: I was including wrong version of SDL_image... #include <SDL/SDL_image.h> instead of #include <SDL2/SDL_image.h>. Everything now works as expected :)