C++ sdl2 flickering on fade animation

Question

I use the following code in my update loop

    if (!flip){
        if (alpha > 0){
            alpha -= Ticks;
        }
        else{
            Ticks = 0;
            flip = true;
        }
    }
    else{
        if (alpha < 255){
            alpha += Ticks;
        }
        else{
            if (transition == 1){
                screenManager->ChangeState(new Menu(render));
            }
            Ticks = 0;
            alpha = 255;
            transition = 1;
            flip = false;
        }

    }

and here is my draw code

        if (transition == 0){
    background->Draw(&screen);
}
else{
    background2->Draw(&screen);
}


SDL_SetRenderDrawColor(render, 0, 0, 0, alpha);
SDL_RenderFillRect(render, &dstrect);

Why does it flicker when running the fade in animation and if possible a solution would be nice.

Answer 1

Fixed the problem and for anyone that wants to know it was due to the fact that the alpha went bellow 0 and above 255 because i was adding a double.