The Portal with RTX DLC was officially released on December 8. It was developed by Nvidia’s Lightspeed Studios as a showcase of its RTX technology, with the Nvidia GeForce RTX 3060 card listed as a minimum requirement. While ray tracing is the core feature of the DLC, Lightspeed has also updated Portal’s textures and models to better showcase the lighting changes. Unsurprisingly, reception to Portal with RTX has been mixed due in no small part to the extreme hardware requirements necessary for a stable frame rate.

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Reddit user Jodeth showcased a special moment from their Portal with RTX playthrough in a recent post. The image they shared isn’t anything surprising. In fact, it’s exactly what any Portal with RTX player would expect, but it’s still exactly what everyone would want to see. The screenshot shows how ray tracing in Portal with RTX allows light to travel through the game’s portals. With one portal in light, the second portal can carry that light into a darkened area.

Light going through a portal in a game based on portals with DLC named Portal with RTX may seem obvious, but it’s still very cool to see in motion. Promising to deliver on the idea on paper is one thing, but to see it actually happening is something else entirely.

Ray tracing technology, for those unfamiliar, is a method for simulating how lighting travels, reflects, refracts, and so on realistically. Most lighting in games, even when presented realistically, does not actually work like real light. It’s faked, and won’t react dynamically to moving objects or complex features. Ray tracing is a step toward realistic lighting that can react, but understandably requires significant PC hardware resources to create a more authentic simulation.

It’s going to be some time before RTX and ray-traced lighting are widely available and used. Most games that do, like Portal with RTX, are better described as technical experiments or art pieces. Hardware performance needs to grow more powerful for something like ray tracing to become normal. Still, if it means light can travel through portals, it’s clearly worth continuing to pursue.

Portal with RTX is available now on PC.

MORE: 10 Need-To-Know Details About Ray Tracing