My code has a lot of geometry codes, thinks that shouldn't be represented just by comments I don't know if it exists, but should be fine to insert images like png in the middle of codes explaning that math behind, just in case I forget what any classes/method/lines do in future. Thanks.
Other than ASCII art? No, not that I'm aware of. The closest you could get would be documentation generators like doxygen that will create documentation files from comments, which might also include markup for images.
Besides that you could link to images using URLs, which are clickable in most editors and/or use markdown for basic formatting.