SDL2 doesn't have the right primitives for easy dear imgui use; there's no renderer-agnostic support for drawing arbitrary textured triangle lists. So you have

SDL2 doesn't have the right primitives for easy dear imgui use; there's no renderer-agnostic support for drawing arbitrary textured triangle lists. So you have to get right in there and do your own drawing, which is (depending on renderer) anything from straightforward (and SDL will even give you a hand) to tiresome. There's a longstanding sporadically-updated fork of SDL that kind of fixes this, but it's something that the SDL team don't seem to have much interest in. See https://bugzilla.libsdl.org/show_bug.cgi?id=1734 https://bugzilla.libsdl.org/show_bug.cgi?id=1734