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Transparency error PNL_image PNG

I upload a PNG file (with some transparent places) to my SDL application.

Googling on how to do this provided me with this sample code:

SDL_Surface *LoadImage(std::string filename)
{
    SDL_Surface* loaded_image = 0, compatible_image = 0;

    if (!filename.c_str())
        return 0;

    loaded_image = IMG_Load(filename.c_str());

    if (!loaded_image)
        return 0;

    compatible_image = SDL_DisplayFormat(loaded_image);

    SDL_FreeSurface(loaded_image);

    return compatible_image;
}

But when the line is reached compatible_image = SDL_DisplayFormat(loaded_image);, the application stops with a fatal exception (it try { /* ... */ } catch (...) { /* ... */ }does not even help). Replace SDL_DisplayFormat()with SDL_DisplayFormatAlpha()also did not help. So, I just deleted the lines causing the exception and downloaded this code to load the images:

SDL_Surface *LoadImage(std::string filename)
{
    if (!filename.c_str())
        return 0;

    return IMG_Load(filename.c_str());
}

And I found such an unpleasant thing: when some sprite overlays the transparent pieces of another, artifacts appear. Something like that:

normal state

artifacts appearing

I am animating my “hero” with this simple algorithm:

// SDL_Surface sprite = LoadImage("hero.bmp");
// hero.bmp contains animation frames followed one-by-one in a single line
// spriteFrameCnt is a number of animation frames
// spriteWidth and spriteHeight contain single frame params

SDL_Rect srcRect;
srcRect.x = spriteFrame * spriteWidth;
srcRect.w = spriteWidth;
srcRect.y = 0;
srcRect.h = spriteHeight;
spriteFrame = ++spriteFrame % spriteFrameCnt;

SDL_BlitSurface(sprite, &srcRect, screen, &rcSprite);

How can this be explained and fixed?

+5
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first example

second example

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+1

SDL_DisplayFormatAlpha SDL_DisplayFormat. .

+6

, , , SDL_Init SDL_DisplayFormat

+1

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