RAY OF LIGHT

With ray tracing making headlines we chat to Tomasz Szałkowski, Techland’s rendering director, on what it means for the future of games

OPM: What is ray tracing and how will it change how we experience games?

Tomasz Szałkowski: Ray tracing is a technique for achieving photorealistic graphical effects (and other effects, such as realistic audio) which require information gathered from a scene’s geometry. It works based on the ability to determine the intersect point of a ray cast in any given direction from any given point in a 3D scene represented in a search-optimised form. This technique can be mixed in with any of the other, already-existing algorithms and effects. With modern hardware, ray tracing can even completely replace rasterisation in less complicated scenes or effect sequences. There hasn’t been a new technology this hot in a long time; the interest in ray tracing and the pace of software adaptation is unprecedented. Currently, the most popular approach is a hybrid one, using rasterisation plus ray tracing. This approach does not cut off users without the required hardware and allows for the relatively smooth transition of individual elements of an engine to the new technology. For upcoming titles, this means increased realism in terms of lighting, shadows and object surfaces, as well as better audio and even AI algorithms.

OPM: Is there something in Dying Light 2 that will benefit from ray tracing?

TS: Dying Light 2 is the largest game created using our in-house C-engine. It is very important for us to achieve our ambitions in terms of graphics, which is why this will be the first Techland production to support ray tracing. We are implementing it in cooperation with Nvidia [on PC] and using the latest achievements in this domain. Thanks to this technology, our shadows in sunny weather look like they really would (among other reasons, because they take into account the size of the sun in the sky). Ambient occlusion effects have gained spatial stability and no longer suffer from compromises tied to the specifics of effects affecting screen space (they operate only on what is visible on the screen, meaning the floor under a table doesn’t affect the displayed image when we look down at the table top). Dark Zones are an important element of our game, which is why we are experimenting with secondary illumination (reflected off surfaces) from artificial light sources (such as the player’s flashlight), which will make the experience of exploring these regions even more intense. As we experiment with this new technology, we can’t help but want to keep trying new effects or change existing ones, so this list might yet change.

OPM: Can this be added to older games running on new hardware?

TS: Definitely. Most of the work is tied to creating and updating scenes for the needs of raytracing. Then that scene can be used in multiple passes, achieving different effects.

OPM: Is this something only large studios can make use of?

TS: This technology is available to anyone with the right hardware. In the near future, that will no longer be a barrier. This year AMD cards supporting ray tracing will be available and we also expect the next generation of RTX cards from Nvidia to come out. I think Intel will join that club as well and the new generation of consoles will also support ray tracing. Widely available engines already support ray tracing, so everyone can try it out.

Small projects even have a certain advantage: thanks to the lower complexity of their scene, they can use ray tracing to a greater degree than complicated open-world Triple-A games.

OPM: Is there a downside to using ray tracing? Will it harm framerates?

TS: I wouldn’t look at ray tracing as an element that causes performance problems. This is a technology, an API, part of DX12. Effects built off the use of ray tracing might be computationally intense in the very nature of the effect; for example, gathering light coming from all directions around a pixel is a very heavy task if you take a straightforward approach. You need to use well-known optimisation tricks and develop new ones. Invest in what pays off. Like everything new, with ray tracing it will take time for everyone to learn how to use it effectively. It was the same with every advance in the world of graphics where mature technology would often be placed in direct comparison with new technology. The success of that new technology drives the research that goes into new hardware generations. I think in a few years, ray tracing will be something completely standard.