Horizon Forbidden West: how the Decima engine evolves for PS5
Guerrilla Games’ Decima Engine is evolving – and in more than one direction. Over the next couple of months we will see its existing iteration deployed on PC with the arrival of conversions of both Death Stranding and Horizon Zero Dawn. However, it’s in the reveal of Horizon Forbidden West for PlayStation 5 that we see the very latest work on Decima and our first look at how Guerrilla intends to deploy its technology on next generation console technology. With that in mind, we decided to take a look at the Forbidden West reveal trailer, to get some idea of the studio’s next-gen vision.
The big challenge facing Guerrilla was exactly to expand on its existing work, simply because the iteration of Decima as seen in Death Stranding is already in a league of its own. However, as advanced as the tech is, it is fundamentally shackled to the constraints of a 2013 console design, and some shortcuts and compromises are in evidence – so for example, interaction with the world’s rich foliage is somewhat minimal. While the Forbidden West trailer does not show off much in the way of direct character interaction with foliage, we do get to see scenes where tall grass flows in the breeze with a rolling pattern dictated by the wind. There’s also secondary motion from foliage on the back of the gigantic tortoise mech, reacting to the behemoth’s primary movements. There is still the sense that this is work-in-progress though: in the scene where the trackers subdue the bot, there’s no physical reaction from foliage when it stamps the ground or falls down – something we’d expect to see addressed in the final code.
Actual foliage density is also an area where Guerrilla is making strides with Horizon Forbidden West. In the original game, the focus on detail is mostly in the foreground surrounding Aloy, with shadow maps, detail and overall LOD cut dramatically further into the distance (I really can’t wait to see how this changes on PC). For Death Stranding, the priorities changed since that game had less foliage, which is expensive to render. Foliage wasn’t quite so dense, but perhaps because of that, more of it could rendered further into the mid-distance, and even smaller elements like rocks closer to the camera received an upgrade in detail.
Horizon Forbidden West essentially delivers a ‘best of both worlds’ scenario – and then some. Texture detail and mesh density is on the upper end of the scale compared to Death Stranding, but there’s the great technological leap brought about by AMD’s generational leap in rendering power, meaning more foliage pushed out further into the distance. Even smaller scale detail is retained further away from the camera, even casting high precision shadows. Compare and contrast with the original Horizon: here, shadow maps tended to be of a rather lower resolution unless they were immediately next to the player camera. This generational change of asset detail and shadow detail is best seen in the closing shot of the trailer, where you can see swaying foliage moving far out into the distance.
