Greetings. I have a Master's Degree in Software Engineering and am experienced with C++. I also used both LÖVE and PICO-8 in making games, but I want to try to write a Libretro core itself.
I took a look at the Libretro API and got a lot of trouble with figuring out how to actually display graphics. Because I plan on making SNES-style games, my idea was to use .png files of sprites. So far, I figured out that I would use the RGB565 format and software rendering instead of targeting a specific graphics API, but I got stuck here. Apparently, I have to write to either a framebuffer or a backbuffer, but I have no idea how. I actually am still quite new at drawing graphics; I did not even know about the RGB565 format until I saw the libretro.h file! I know that Libretro uses its own png decoder (rpng), but I do not know how to use that, either.
What I want to do specifically is to be able to draw and move the png-based sprites on-screen, preferably while using a physics engine such as Box2D or Chipmunk.
I appreciate everyone's response here. I am enthusiastic on making a game using this Libretro API.