C++ - Display continuously updating image - c++

Question

I have written a pathtracer in C++, and now I want to display the rendering process in real time, so I'm wondering what the simplest/best way to do this is.
Basically, the rendered image updates after every iteration, so I just need to retrieve it, display it in a separate window, and update it.
I was thinking about using DirectX, and it seems that I could probably also do it with OpenCV, but I'm just looking for a simple way which doesn't require adding a lot of new code.
I am using C++ on Windows.

Answer 1

If I understand correctly your path tracer probably outputs a color per emitted ray? If that is the case, and you are thinking about displaying the rendered image in a separate window I'd suggest using SDL2. There's a great set of tutorials concerning real-time graphics using C++ and SDL by Lazy Foo' Productions.
Excerpt taken from official SDL documentation (without cruft needed to initialize windows) regarding SDL_Surface, which you will probably be using:
/* This is meant to show how to edit a surface's pixels on the CPU, but
normally you should use SDL_FillRect() to wipe a surface's contents. */
void WipeSurface(SDL_Surface *surface)
{
/* This is fast for surfaces that don't require locking. */
/* Once locked, surface->pixels is safe to access. */
SDL_LockSurface(surface);
/* This assumes that color value zero is black. Use
SDL_MapRGBA() for more robust surface color mapping! */
/* height times pitch is the size of the surface's whole buffer. */
SDL_memset(surface->pixels, 0, surface->h * surface->pitch);
SDL_UnlockSurface(surface);
}