Abstract: Many interactive applications strive for realistic renderings, but framerate constraints usually limit realism to effects that run efficiently in graphics hardware. One effect largely ignored in such applications is refraction. We introduce a simple, image-space approach to refractions that easily runs on modern graphics cards. Our method requires two passes on a GPU, and allows refraction of a distant environment through two interfaces, compared to current interactive techniques that are restricted to a single interface. Like all image-based algorithms, aliasing can occur in certain circumstances, but the plausible refractions generated with our approach should suffice for many applications.