4 ms·

The most expensive step in ray marching is to find the distance which you will get for free after one rasterization pass via the z-buffer. With the z-buffer alr

by sprash 6y ago

The most expensive step in ray marching is to find the distance which you will get for free after one rasterization pass via the z-buffer. With the z-buffer already present every effect used in this demo can be applied in the same way to purely rasterized graphics with even less cost. E.g. Doom Eternal has very elaborated dynamic lighting effects but uses 100% forward rendering. RTX is completely pointless.

dahart 6y ago
> The most expensive step in ray marching is to find the distance which you will get for free after one rasterization pass via the z-buffer. Not true, you can't make that claim. The most expensive step depends entirely on what you render. The material can easily be more expensive than the SDF. > With the z-buffer already present every effect used in this demo can be applied in the same way to purely rasterized graphics with even less cost. You're completely forgetting that shadows are a thing. > RTX is completely pointless. I interpret that to mean that either 1- you're mad at Nvidia for various reasons not particularly related to RTX, or 2- you don't know what RTX actually does.
- sprash 6y ago
  > The material can easily be more expensive than the SDF. But you still don't have to calculate the SDF in the first place. Which means one step less computation for your material. Also geometries with high object counts are not as slow as it is the case with SDF. > You're completely forgetting that shadows are a thing. Those are being done via stencil buffers since doom3. And for non-point-like sources you have a bag of tricks available via shaders to make them soft. No RTX needed! > you don't know what RTX actually does. I know what RTX does. As long as the results are so subtle to the point where on some screenshot comparisons you can't even tell which one is with or without, RTX is completely pointless especially when it comes with a performance penalty.
  - dahart 6y ago
    Why are you arguing about SDFs? The demo you linked proves nothing about what either games do nor what RTX does, in the context of this thread it’s irrelevant whether z-buffers save you one iteration of ray marching. Not needing a special shadow map or stencil volume or a big bag of tricky tricks for area lights is one of the reasons to use ray tracing & RTX. The main point of RTX is faster ray tracing. You’re complaining about the screenshot marketing of specific games, not really demonstrating an understanding the tradeoffs of ray tracing. It’s fine if you don’t see any advantage to having ray tracing in Control or Battlefield, and/or don’t like the idea that some people see value in better visuals or easier development. That means you don’t like it. I see a point even if you don’t.

by sprash 6y ago

dahart 6y ago

> The most expensive step in ray marching is to find the distance which you will get for free after one rasterization pass via the z-buffer. Not true, you can't make that claim. The most expensive step depends entirely on what you render. The material can easily be more expensive than the SDF. > With the z-buffer already present every effect used in this demo can be applied in the same way to purely rasterized graphics with even less cost. You're completely forgetting that shadows are a thing. > RTX is completely pointless. I interpret that to mean that either 1- you're mad at Nvidia for various reasons not particularly related to RTX, or 2- you don't know what RTX actually does.

sprash 6y ago
> The material can easily be more expensive than the SDF. But you still don't have to calculate the SDF in the first place. Which means one step less computation for your material. Also geometries with high object counts are not as slow as it is the case with SDF. > You're completely forgetting that shadows are a thing. Those are being done via stencil buffers since doom3. And for non-point-like sources you have a bag of tricks available via shaders to make them soft. No RTX needed! > you don't know what RTX actually does. I know what RTX does. As long as the results are so subtle to the point where on some screenshot comparisons you can't even tell which one is with or without, RTX is completely pointless especially when it comes with a performance penalty.
- dahart 6y ago
  Why are you arguing about SDFs? The demo you linked proves nothing about what either games do nor what RTX does, in the context of this thread it’s irrelevant whether z-buffers save you one iteration of ray marching. Not needing a special shadow map or stencil volume or a big bag of tricky tricks for area lights is one of the reasons to use ray tracing & RTX. The main point of RTX is faster ray tracing. You’re complaining about the screenshot marketing of specific games, not really demonstrating an understanding the tradeoffs of ray tracing. It’s fine if you don’t see any advantage to having ray tracing in Control or Battlefield, and/or don’t like the idea that some people see value in better visuals or easier development. That means you don’t like it. I see a point even if you don’t.