Real-world objects reflect incident light in different directions. In computer graphics, the most common way to capture the distribution of these reflected directions is to rely on a mathematical function called GGX. Nowadays, the GGX distribution is extremely popular and is used in every CGI movie and video game.

In this work, we introduce a novel algorithm to evaluate this distribution. Our algorithm is simpler than the state-of-the-art and leads to faster performance, thereby offering systematic speed-ups to the aforementioned applications.

Our algorithm is based on the insight that any material represented as a GGX distribution can be reduced to a hemispherical mirror. This mirror is extremely simple to simulate on a computer and is what makes our algorithm faster. If you are curious to know more about this technique, feel free to attend our presentation at HPG 2023 in Delf (Netherlands) in June or follow the link below to read the paper.