RTfact: Generic concepts for flexible and high performance ray tracing

Thanks to more than a decade of research and the fast evolution of computer hardware, ray tracing is likely to become a commodity choice for adding complex lighting effects to real-time rendering engines. Nonetheless, interactive ray tracing research has been mostly concentrated on few specific combinations of data structures and algorithms. In this paper we present RTfact - an attempt to bring the different aspects of ray tracing together in a component oriented, generic, and portable way, without sacrificing the performance benefits of hand-tuned single-purpose implementations. RT-fact is a template library consisting of packet-centric components combined into an efficient ray tracing framework. Our generic design approach with loosely coupled algorithms and data structures allows for easy integration of new algorithms with maximum run-time performance, while leveraging as much of the existing code base as possible. The efficiency of templates allows us to achieve fine component granularity and to incorporate a flexible physically-based surface shading model, which enables exploitation of ray coherence. As a proof of concept we apply the library to a variety of rendering tasks and demonstrate its ability to deliver performance equal to currently existing optimized implementations.