Mesa Merge Pending For Vulkan Ray-Tracing On Older AMD GPUs

[JPFSanders]

A useless thing. Old video cards are weak for RT.

Can be useful for development work or for CAD applications where framerate is not that important.

[arQon]

The article is probably harsher than it needs to be.

What part of the article did you think was harsh? It didn't read like that to me at all. (Apart from the AMD comments, which seem accurate and thus justified).

> Right now this passes CTS the same as on RDNA 2 cards

Well, that's a pretty nice place to be.

> 300 lines of new code

Also a nice place to be.

This is really good stuff. It's obviously not going to be as fast as natively-capable RTRT HW, duh, but that *doesn't matter*. What matters is the ability to have it run moderately well at all, and at lower settings this sort of offload is perfectly adequate given a competent engine, as Crytek demonstrated years ago. The RTX20xx series aren't "fast enough" for RT either, but that doesn't stop people being able to have at least *some* RT effects in their games, especially in slower-paced stuff like RPGs etc.

[pal666]

rt is slow even on fast gpus. why would i want it on slow gpu in software emulation?

[smitty3268]

rt is slow even on fast gpus. why would i want it on slow gpu in software emulation?

You wouldn't, which is why it's disabled by default.

It's nice for devs and people wanting to test rt on old hardware without the feature, though.

[mitch074]

rt is slow even on fast gpus. why would i want it on slow gpu in software emulation?

It's not software emulation in a strict sense, it's using generic shaders to perform ray tracing calculations - so it WILL be faster than CPU-based ray tracing on any card that's not more than 6 years old. This helps in debugging, still frame rendering etc. and in some cases we might even get a playable game at very low resolution - considering Quake II could be played and enjoyed in 320x240, it may just be a nice touch to play it in 640x480 in full RT glory.
Also, provided the implementation is well tweaked, some cards may just give unexpected results - Polaris comes to mind as a capable architecture when there's a bunch of shaders to compute, and may provide quite interesting results.
Also note that early Nvidia RTX implementations actually ran on non-RTX capable cards - so it's not a dumb idea.

[M@GOid]

If memory didn't fail me, Nvidia also released ray tracing on their older cards, with the intention to accelerate the interest and development of rt in games.

This is a good move for AMD, even if not by them. Right now most rt games and demos out there are tainted, developed exclusively for Nvidia cards, for various reasons. So is important to get rt on AMD and Intel ASAP, so future projects don't target Nvidia exclusively.

[pal666]

It's not software emulation in a strict sense, it's using generic shaders to perform ray tracing calculations - so it WILL be faster than CPU-based ray tracing on any card that's not more than 6 years old.

i understand it, but it's obviously slower than special instructions on newer gpus.

and in some cases we might even get a playable game at very low resolution - considering Quake II could be played and enjoyed in 320x240, it may just be a nice touch to play it in 640x480 in full RT glory.

this is part i don't understand. why play it in 640x480 when you have fullhd monitor? seems like a lot of work to reduce picture quality

it's not a dumb idea.

to be clear, i'm not telling people what to do, i'm just trying to find a usecase for myself

[TemplarGR]

I remember AMD presenting a ray tracing demo running on an old Opengl 3.3 era HD 4870.... I also remember all the fights i had online with Nvidia fanboys when RTX was initially released, because i kept telling them that raytracing is not some super-duper mystical technology, they are just shaders and could potentially run on current hardware as well.... Well, when Nvidia supported it on Pascal cards and now open source AMD drivers have it on pre-Navi hardware, it seems i was correct after all, who knew?

Still, i believe that ray tracing as it stands today is just a useless gimmick. I haven't been convinced that modern games can't be even better with traditional techniques, and also perform better. In fact, most of current raytracing supporting games look worse and less realistic to me.

[bridgman]

this is part i don't understand. why play it in 640x480 when you have fullhd monitor? seems like a lot of work to reduce picture quality
to be clear, i'm not telling people what to do, i'm just trying to find a usecase for myself

One part of the answer is probably "just to see what it looks like", but I think the primary answer is that in some cases people may prefer the combination of ray traced graphics and lower resolution over conventional graphics and higher resolution. That would probably not be the most common scenario but there may be some cases.

Still, i believe that ray tracing as it stands today is just a useless gimmick. I haven't been convinced that modern games can't be even better with traditional techniques, and also perform better. In fact, most of current raytracing supporting games look worse and less realistic to me.

Don't know for sure, but my understanding is that it takes a massive amount of developer effort to get sophisticated lighting with conventional techniques while getting close to the same results with ray tracing can be a lot easier and faster.

I'm not suggesting that game development will get easier and nothing else will change, but rather that once game developers have had the chance to spend more time with ray tracing they may be able to get same or better results with same or less effort.

[Dagelf]

After playing Q2RTX non-RTX games are ruined for me, the subtle lighting and shadows just pushes the immersion ever so slightly closer to a feeling natural... Lots of games that claim RTX literally only uses it for reflections and totally miss the point by overlaying so many effects on top that the point is lost.

As for hardware support... BS I say. All marketing. They're doing most of it in firmware. Some of the raymarching demos on Shadertoy run at 60 fps on 15 year old cards