5 ms·

What's wrong with hardware raytracing?

Negitivefrags 1y ago
There are a lot of theoretical arguments I could give you about how almost all cases where hardware BVH can be used, there are better and smarter algorithms to be using instead. Being proud of your hardware BVH implementation is kind of like being proud of your ultra-optimised hardware bubblesort implementation. But how about a practical argument instead. Enabling raytracing in games tends to suck. The graphical improvements on offer are simply not worth the performance cost. A common argument is that we don't have fast enough hardware yet, or developers haven't been able to use raytracing to it's fullest yet, but it's been a pretty long damn time since this hardware was mainstream. I think the most damning evidence of this is the just released Battlefield 6. This is a franchise that previously had raytracing as a top-level feature. This new release doesn't support it, doesn't intend to support it. And in a world where basically every AAA release is panned for performance problems, BF6 has articles like this: https://www.pcgamer.com/hardware/battlefield-6-this-is-what-a-well-optimised-game-looks-like-in-2025/ https://www.pcgamer.com/hardware/battlefield-6-this-is-what-...
- noir_lord 1y ago
  > But how about a practical argument instead. Enabling raytracing in games tends to suck. The graphical improvements on offer are simply not worth the performance cost. Pretty much this - even in games that have good ray tracing, I can't tell when it's off or on (except for the FPS hit) - I cared so little I bought a card not known to be good at it (7900XTX) because the two games I play the most don't support it anyway. They oversold the technology/benefits and I wasn't buying it.
  - ahoka 1y ago
    There were and always are people who swear to not see the difference with anything above 25hz, 30hz, 60hz, 120hz, HD, Full HD, 2K, 4K. Now it's ray-tracing, right.
    - noir_lord 1y ago
      Glad you intimately know how my perception of lighting in games works better than I do - though I'm curious how you do.
    - array_key_first 1y ago
      I can see the difference in all of those. I can even see the difference between 120hz and 240hz, and now I play on 240hz. Ray tracing looks almost indistinguishable from really good rasterized lighting in MOST conditions. In scenes with high amounts of gloss and reflections, it's a little more pronounced. A little. From my perspective, you're getting, like, a 5% improvement in only one specific aspect of graphics in exchange for a 200% cost. It's just not worth it.
      - 1gn15 1y ago
        Doesn't gel with my experience. CP2077 rasterization vs ray tracing vs path tracing is like night and day. Rasterization looks "gamey". Path tracing makes it look pre-rendered. Huge difference.
        array_key_first 1y ago
        CP2077 purposefully has as many glossy surfaces as humanly possible just for this affect. It somewhat makes sense with the context. Everything is chrome in the future, I guess. As soon as you remove the ridiculous amounts of gloss, the difference is almost imperceptible.
    - foldr 1y ago
      There’s an important distinction between being able to see the difference and caring about it. I can tell the difference between 30Hz and 60Hz but it makes no difference to my enjoyment of the game. (What can I say - I’m a 90s kid and 30fps was a luxury when I was growing up.) Similarly, I can tell the difference between ray traced reflections and screen space reflections because I know what to look for. But if I’m looking, that can only be because the game itself isn’t very engaging.
  - keyringlight 1y ago
    I think one of the challenges is that game designers have trained up so well at working within the non-RT constraints (and pushing back those constraints) that it's a tall order to make paying the performance cost (and new quirks of rendering) be paid back by RT improvements. There's also how a huge majority of companies wouldn't want to cut off potential customers in terms of whether their hardware can do RT at all or performance while doing so. The other big one is whether they're trying to recreate a similar environment with RT, or if they're taking advantage of what is only possible on the new technique, such as dynamic lighting and whether that's important to the game they want to make.
  - ThatPlayer 1y ago
    To me, the appeal is that game environments that can now be way more dynamic because we're not being limited by prebaked lighting. The Finals does this, but doesn't require ray tracing and it's pretty easy to tell when ray tracing is enabled: https://youtu.be/MxkRJ_7sg8Y https://youtu.be/MxkRJ_7sg8Y But that's a game design change that takes longer
- asah 1y ago
  naive q: could games detect when the user is "looking around" at breathtaking scenery and raytrace those? offer a button to "take picture" and let the user specify how long to raytrace? then for heavy action and motion, ditch the raytracing? even better, as the user passes through "scenic" areas, automatically take pictures in the background. Heck, this could be an upsell kind of like the RL pictures you get on the roller coaster... #donthate (sorry if obvious / already done)
  - danparsonson 1y ago
    Not exactly the same but adaptive rendering based on viewer attention reminded me of this: https://en.wikipedia.org/wiki/Foveated_rendering https://en.wikipedia.org/wiki/Foveated_rendering
  - keyringlight 1y ago
    Even without RT I think it'd be beneficial to tune graphics settings depending on context, if it's an action/combat scene there's likely aspects the player isn't paying attention to. I think the challenge is it's more developer work whether it's done by implementing some automatic detection or manually being set scene by scene during development (which studios probably do already where they can set up specific arenas). I'd guess an additional task is making sure there's no glaring difference between tuning levels, and setting a baseline you can't go beneath.
  - 1gn15 1y ago
    CP2077 has a "path tracing in photo mode" setting.
- ThatPlayer 1y ago
  > Enabling raytracing in games tends to suck. Because enabling raytracing means the game supports non-raytracing too. Which limits the game's design on how they can take advantage of raytracing being realtime. The only exception to this I've seen The Finals: https://youtu.be/MxkRJ_7sg8Y https://youtu.be/MxkRJ_7sg8Y . Made by ex-Battlefield devs, the dynamic environment from them 2 years ago is on a whole other level even compared to Battlefield 6.
  - Mawr 1y ago
    There's also Metro: Exodus, which the developers have re-made to only support RT lighting. DigitalFoundry made a nice video on it: https://www.youtube.com/watch?v=NbpZCSf4_Yk https://www.youtube.com/watch?v=NbpZCSf4_Yk
- TiredOfLife 1y ago
  > But how about a practical argument instead. With raytracing lighting a scene goes from taking hours-days to just designating objects that emit light
Our_Benefactors 1y ago
Not OP, but a lot of the current kvetching about hardware based ray tracing is that it’s basically an nvidia-exclusive party trick, similar to DLSS and physx. AMD has this inferiority complex where nvidia must not be allowed to innovate with a hardware+software solution, it must be pure hardware so AMD can compete on their terms.
diffeomorphism 1y ago
Much higher resource demands, which then requires tricks like upscaling to compensate. Also you get uneven competition between GPU vendors because it is not hardware ray tracing but Nvidia raytracing in practice. On a more subjective note, you get less interesting art styles because studio somehow have to cram raytracing as a value proposition in there.
bob1029 1y ago
It will never be fast enough to work in real time without compromising some aspect of the player's experience. Ray tracing is solving the light transport problem in the hardest way possible. Each additional bounce adds exponentially more computational complexity. The control flows are also very branchy when you start getting into the wild indirect lighting scenarios. GPUs prefer straight SIMD flows, not wild, hierarchical rabbit hole exploration. Disney still uses CPU based render farms. There's no way you are reasonably emulating that experience in <16ms. The closest thing we have to functional ray tracing for gaming is light mapping. This is effectively just ray tracing done ahead of time, but the advantage is you can bake for hours to get insanely accurate light maps and then push 200+ fps on moderate hardware. It's almost like you are cheating the universe when this is done well. The human brain has a built in TAA solution that excels as frame latencies drop into single digit milliseconds.
- zubspace 1y ago
  The problem is the demand for dynamic content in AAA games. Large exterior and interior worlds with dynamic lights, day and night cycle, glass and translucent objects, mirrors, water, fog and smoke. Everything should be interactable and destructable. And everything should be easy to setup by artists. I would say, the closest we can get are workarounds like radiance cascades. But everything else than raytracing is just an ugly workaround which falls apart in dynamic scenarios. And don't forget that baking times and storing those results, leading to massive game sizes, are a huge negative. Funnily enough raytracing is also just an approximation to the real world, but at least artists and devs can expect it to work everywhere without hacks (in theory).
- sintax 1y ago
  > It will never be fast enough to work in real time ... 640Kb surely is enough!
- TiredOfLife 1y ago
  How is Metro Exodus Enhanced Edition (that is purely raytraced) compromised compared to regular version that uses traditional lighting?
- 1y ago
Mawr 1y ago
1. People somehow think that just because today's hardware can't handle RT all that well it will never be able to. A laughable position of course. 2. People turn on RT in games not designed with it in mind and therefore observe only minor graphical improvements for vastly reduced performance. Simple chicken-and-egg problem, hardware improvements will fix it.

There are a lot of theoretical arguments I could give you about how almost all cases where hardware BVH can be used, there are better and smarter algorithms to be using instead. Being proud of your hardware BVH implementation is kind of like being proud of your ultra-optimised hardware bubblesort implementation. But how about a practical argument instead. Enabling raytracing in games tends to suck. The graphical improvements on offer are simply not worth the performance cost. A common argument is that we don't have fast enough hardware yet, or developers haven't been able to use raytracing to it's fullest yet, but it's been a pretty long damn time since this hardware was mainstream. I think the most damning evidence of this is the just released Battlefield 6. This is a franchise that previously had raytracing as a top-level feature. This new release doesn't support it, doesn't intend to support it. And in a world where basically every AAA release is panned for performance problems, BF6 has articles like this: https://www.pcgamer.com/hardware/battlefield-6-this-is-what-a-well-optimised-game-looks-like-in-2025/ https://www.pcgamer.com/hardware/battlefield-6-this-is-what-...

noir_lord 1y ago
> But how about a practical argument instead. Enabling raytracing in games tends to suck. The graphical improvements on offer are simply not worth the performance cost. Pretty much this - even in games that have good ray tracing, I can't tell when it's off or on (except for the FPS hit) - I cared so little I bought a card not known to be good at it (7900XTX) because the two games I play the most don't support it anyway. They oversold the technology/benefits and I wasn't buying it.
- ahoka 1y ago
  There were and always are people who swear to not see the difference with anything above 25hz, 30hz, 60hz, 120hz, HD, Full HD, 2K, 4K. Now it's ray-tracing, right.
  - noir_lord 1y ago
    Glad you intimately know how my perception of lighting in games works better than I do - though I'm curious how you do.
  - array_key_first 1y ago
    I can see the difference in all of those. I can even see the difference between 120hz and 240hz, and now I play on 240hz. Ray tracing looks almost indistinguishable from really good rasterized lighting in MOST conditions. In scenes with high amounts of gloss and reflections, it's a little more pronounced. A little. From my perspective, you're getting, like, a 5% improvement in only one specific aspect of graphics in exchange for a 200% cost. It's just not worth it.
    - 1gn15 1y ago
      Doesn't gel with my experience. CP2077 rasterization vs ray tracing vs path tracing is like night and day. Rasterization looks "gamey". Path tracing makes it look pre-rendered. Huge difference.
      - array_key_first 1y ago
        CP2077 purposefully has as many glossy surfaces as humanly possible just for this affect. It somewhat makes sense with the context. Everything is chrome in the future, I guess. As soon as you remove the ridiculous amounts of gloss, the difference is almost imperceptible.
  - foldr 1y ago
    There’s an important distinction between being able to see the difference and caring about it. I can tell the difference between 30Hz and 60Hz but it makes no difference to my enjoyment of the game. (What can I say - I’m a 90s kid and 30fps was a luxury when I was growing up.) Similarly, I can tell the difference between ray traced reflections and screen space reflections because I know what to look for. But if I’m looking, that can only be because the game itself isn’t very engaging.
- keyringlight 1y ago
  I think one of the challenges is that game designers have trained up so well at working within the non-RT constraints (and pushing back those constraints) that it's a tall order to make paying the performance cost (and new quirks of rendering) be paid back by RT improvements. There's also how a huge majority of companies wouldn't want to cut off potential customers in terms of whether their hardware can do RT at all or performance while doing so. The other big one is whether they're trying to recreate a similar environment with RT, or if they're taking advantage of what is only possible on the new technique, such as dynamic lighting and whether that's important to the game they want to make.
- ThatPlayer 1y ago
  To me, the appeal is that game environments that can now be way more dynamic because we're not being limited by prebaked lighting. The Finals does this, but doesn't require ray tracing and it's pretty easy to tell when ray tracing is enabled: https://youtu.be/MxkRJ_7sg8Y https://youtu.be/MxkRJ_7sg8Y But that's a game design change that takes longer
asah 1y ago
naive q: could games detect when the user is "looking around" at breathtaking scenery and raytrace those? offer a button to "take picture" and let the user specify how long to raytrace? then for heavy action and motion, ditch the raytracing? even better, as the user passes through "scenic" areas, automatically take pictures in the background. Heck, this could be an upsell kind of like the RL pictures you get on the roller coaster... #donthate (sorry if obvious / already done)
- danparsonson 1y ago
  Not exactly the same but adaptive rendering based on viewer attention reminded me of this: https://en.wikipedia.org/wiki/Foveated_rendering https://en.wikipedia.org/wiki/Foveated_rendering
- keyringlight 1y ago
  Even without RT I think it'd be beneficial to tune graphics settings depending on context, if it's an action/combat scene there's likely aspects the player isn't paying attention to. I think the challenge is it's more developer work whether it's done by implementing some automatic detection or manually being set scene by scene during development (which studios probably do already where they can set up specific arenas). I'd guess an additional task is making sure there's no glaring difference between tuning levels, and setting a baseline you can't go beneath.
- 1gn15 1y ago
  CP2077 has a "path tracing in photo mode" setting.
ThatPlayer 1y ago
> Enabling raytracing in games tends to suck. Because enabling raytracing means the game supports non-raytracing too. Which limits the game's design on how they can take advantage of raytracing being realtime. The only exception to this I've seen The Finals: https://youtu.be/MxkRJ_7sg8Y https://youtu.be/MxkRJ_7sg8Y . Made by ex-Battlefield devs, the dynamic environment from them 2 years ago is on a whole other level even compared to Battlefield 6.
- Mawr 1y ago
  There's also Metro: Exodus, which the developers have re-made to only support RT lighting. DigitalFoundry made a nice video on it: https://www.youtube.com/watch?v=NbpZCSf4_Yk https://www.youtube.com/watch?v=NbpZCSf4_Yk
TiredOfLife 1y ago
> But how about a practical argument instead. With raytracing lighting a scene goes from taking hours-days to just designating objects that emit light

Our_Benefactors 1y ago

Not OP, but a lot of the current kvetching about hardware based ray tracing is that it’s basically an nvidia-exclusive party trick, similar to DLSS and physx. AMD has this inferiority complex where nvidia must not be allowed to innovate with a hardware+software solution, it must be pure hardware so AMD can compete on their terms.

diffeomorphism 1y ago

Much higher resource demands, which then requires tricks like upscaling to compensate. Also you get uneven competition between GPU vendors because it is not hardware ray tracing but Nvidia raytracing in practice. On a more subjective note, you get less interesting art styles because studio somehow have to cram raytracing as a value proposition in there.

bob1029 1y ago

It will never be fast enough to work in real time without compromising some aspect of the player's experience. Ray tracing is solving the light transport problem in the hardest way possible. Each additional bounce adds exponentially more computational complexity. The control flows are also very branchy when you start getting into the wild indirect lighting scenarios. GPUs prefer straight SIMD flows, not wild, hierarchical rabbit hole exploration. Disney still uses CPU based render farms. There's no way you are reasonably emulating that experience in <16ms. The closest thing we have to functional ray tracing for gaming is light mapping. This is effectively just ray tracing done ahead of time, but the advantage is you can bake for hours to get insanely accurate light maps and then push 200+ fps on moderate hardware. It's almost like you are cheating the universe when this is done well. The human brain has a built in TAA solution that excels as frame latencies drop into single digit milliseconds.

zubspace 1y ago
The problem is the demand for dynamic content in AAA games. Large exterior and interior worlds with dynamic lights, day and night cycle, glass and translucent objects, mirrors, water, fog and smoke. Everything should be interactable and destructable. And everything should be easy to setup by artists. I would say, the closest we can get are workarounds like radiance cascades. But everything else than raytracing is just an ugly workaround which falls apart in dynamic scenarios. And don't forget that baking times and storing those results, leading to massive game sizes, are a huge negative. Funnily enough raytracing is also just an approximation to the real world, but at least artists and devs can expect it to work everywhere without hacks (in theory).
sintax 1y ago
> It will never be fast enough to work in real time ... 640Kb surely is enough!
TiredOfLife 1y ago
How is Metro Exodus Enhanced Edition (that is purely raytraced) compromised compared to regular version that uses traditional lighting?
1y ago

Mawr 1y ago

1. People somehow think that just because today's hardware can't handle RT all that well it will never be able to. A laughable position of course. 2. People turn on RT in games not designed with it in mind and therefore observe only minor graphical improvements for vastly reduced performance. Simple chicken-and-egg problem, hardware improvements will fix it.