A new technique for rendering complex portals

In this paper, we identify a general paradigm for portal-based rendering and present an image-space algorithm forrendering complex portals. Our general paradigm is an abstraction of portal-based rendering that is independent of scene geometry. Itprovides a framework for flexible and dynamic scene composition by connecting cells with transformative portals. Our renderingalgorithm maintains a visible volume in image-space and uses fragment culling to discard fragments outside of this volume. Wediscuss our implementation in OpenGL and present results that show it provides correct rendering of complex portals at interactiverates on current hardware. We believe that our work will be useful in many applications that require a means of creating dynamic andmeaningful visual connections between different sets of data.