Video from the articleYes, this is real—and while not perfect, it's fantastic for a fan-made mod.
SAM MACHKOVECH - 4/2/2022, 7:09 AM
Since the launch of Quake II RTX in 2019, fans have kept their eyes peeled for similar ray- and path-tracing updates for other classic '90s shooters. It's fertile upgrade territory, since modern machines push vanilla versions of Doom and Quake to over 1,000 fps by default—that's wiggle room for computationally expensive lighting techniques—but those games's official handlers haven't really moved the ray-tracing needle.
Instead, Friday's good news comes from the Doom community: The first three episodes of Doom 1 (1993) can now be played with top-to-bottom ray tracing enabled. Yes, I know, I see the date at the top of this article, but I swear: I installed and tested Doom within the new PRBoom+RT engine, and the results have not only looked quite good but felt surprisingly performative.
That is helped in large part by native support within the new engine for both Nvidia DLSS and AMD FSR. While you wouldn't need either to run vanilla Doom, both of these upscaling systems help in a ray tracing update because they also shrink the base resolution of so many realistically rendered light bounces. The upscaling toggle makes a big performance difference: On my default testing rig (RTX 3080 Ti, AMD Ryzen 7 5800X overclocked), the "DLSS quality" toggle at 2160p resolution increases ray-tracing performance nearly 100 percent compared to a raw 2160p signal, from 33 fps to 61 fps in E1M1. You can scrape even more frames by playing around with lower-resolution DLSS and FSR settings.
Interestingly, DLSS by default hinges on games having temporal anti-aliasing built in, which means this new, patched version of PRBoom+ may have received a TAA pass just to make Doom's RT mode work on systems with less than the highest-end specs. (This is the kind of overkill, fan-built touch we love at Ars Technica.)
At its best, PRBoom+RT makes the original game look and feel like Doom 3, as previously dim hallways are reborn with the dramatic sense that darkness can loom around any corner. Like Doom 3, this mod includes a "press F for flashlight" keyboard option at any time, and I found that I needed that help in a few moments so far in my testing. Otherwise, in great news, mod creator Sultim Tsyrendashiev has mostly balanced the revamped moody lighting with playability in mind so that pitch-black hallways are the exception, not the rule.
Doom famously added dramatic dynamic lighting touches to the burgeoning FPS genre in ways that blew people away in 1993, but Tsyrendashiev still exposes the way ray-tracing systems can lift an older game with little manual light rigging. Part of this comes from how each texture is updated with material properties, which affects how light bulbs, glowing ooze, explosions, and other light sources bounce off walls and textures to affect their surroundings.
At its worst, some of these materials bounce light in weird ways when viewed from up close, as if someone wrapped certain doors or logos in cellophane. And since this mod revolves around the game's original assets and sprites, you'll sometimes see some weirdness when "realistic" light bounces around an entirely 2D, pixelated imp. But the effect is generally quite handsome when careening through dark hallways and approaching monster closets; I was delighted every time a door opened to let a mild-but-eerie pocket of light in and expose that something just arrived to kill me—especially as my character's shadow realistically lingered over whatever was coming toward me.
The biggest issue with PRBoom+RT's default configuration is a bloom effect that is straight-up garish. Nothing about Doom's aesthetic or clunky military base textures has ever suggested the kind of lens flare that would make J.J. Abrams perk up in his director's chair. Thankfully, the mod's top-most settings menu includes a toggle to either turn this bloom effect down or off entirely.
To run this mod, grab PRBoom+RT's 1.0 version at its Github (currently linked to an external OneDrive folder, but we'll see how long that lasts). Once that's unzipped into its own directory, paste an original Doom "WAD" file (available when purchased through services like Steam and GOG) into the same directory, then run the sole EXE. Be sure to play around in the mod's extensive menus to tweak its graphics to your liking. If anything else in the above screenshots makes you squirm, there's likely an option to retouch it. And keep an eye on Tsyrendashiev's YouTube and GitHub pages, as the coder, who previously released a Serious Sam 1 RT mod, seems poised to eventually do the same for Half-Life.
[youtube]https://www.youtube.com/watch?v=i2Ld9YNUWls[/youtube]
Just a reminder that people are still pushing the original Doom to places it was never intended to go.
