Graphics HXGI Realtime Dynamic GI

RIP

 

Sadly looks like it, RIP!

 

seems like yea. but not really matter now due HDRP pipeline have own solution

 

Lexie hasn't really been active for months here, by the looks of it. He does seem to occasionally visit the forum, but his last post was from

Sep 6, 2019

in the NatCorder - Video Recording API thread.

Hx Volumetric Lighting also became a dead asset at some point in the past.

What's up with "realtime GI" being an apparent cursed thing for Unity? HXGI is the third asset or so that has been abandoned: First SEGI, then LIVENDA's SpectraGI (which never saw the light at all) and now this.

.

 

Its just absurdly complex.

I doubt its possible to tackle this without a proper team and / or investment, same comes with any complex tech.

This kind of requirements should be solved by "engine" team so to speak.

 

I'd certainly agree when it comes to 'one size fits all' attempts to provide solutions. Much smaller dev teams may achieve results that are suitable for their particular project, but taking it far beyond those realms is a significant challenge.

 

How i know, only for Ray Trace hardware, and not on voxels, in realtime

 

not yet. HDRP have RTGI for cards with RTX support and SSGI (Screen Space GI) for non RTX hardware

 

Unity saw that they had several options:
A) Implement real-time GI that can run on all GPUs that will take a lot of effort, have a great performance cost, and be underwhelming at best
B) Implement RTGI which ultimately will produce the most accurate results and cross your fingers that everyone will have a RT-capable GPU soon so that people won't demand support for non-RT-capable GPUs

Seems like they have opted for B, and I can't really say I blame them. But dang I'd like some realtime GI that doesn't require RT.

 

Having an RT capable card is one thing, but what about older projects that are using the built in render pipeline? They can't use HDRP.

 

The built in renderer is not supposed to have a future, especially not in terms of major new features. Plans could always change but at the moment I'd say their decision to extent the lifetime of the older Enlighten solution within Unity is all that built-in users should rely on. And by the time that period ends, the built-in renderer will be far into its wilderness years, with more than feature parity in the new renderers, and a much better sense of what alternative GI solutions are available for the modern graphics pipelines. Either that or the entire plan for graphics will have changed at some point.

I really doubt that Unity want their future GI options to be for hardware that supports raytracing only. But it is difficult to predict because the plans and timescales of this have already changed and Unity are deliberately vague about what the future solution will be now. And if things drag on for a very long time then the equation about how many devices are in users hands that support raytracing will have changed, affecting my doubts about them not going for a solution which only works with such hardware.

 

Unfortunately, you are, of course, correct. I'm working on a long-term research project, so at some point I am going to have to either port to the HDRP (Ugh!) or stop updating my unity version.

Like you, I would be very surprised if unity would be assuming that the majority of their users have access to hardware raytracing. It will be many years before that happens, if it ever does (hardware raytracing could still end up as a fad).

It is still possible that something like hxgi or one of the other aftermarket or third party assets might bring real time GI to the built in RP, especially if it is added to HDRP, and it becomes popular. There could still be demand for it, I suspect most unity users will still be on the built-in RP for at least a few years.

 

Scaling Probe-Based Real-Time Dynamic Global Illumination for Production
http://jcgt.org/published/0010/02/01/

Some other works by Nvidia researchers. And explained in Unity with sample codes.

 

Whew, published on 5/3... hot off the digital presses! That certainly looks interesting.

 

That looks a bit like the stuff that they had showed at Unite 2019?!

 

RTX only... well I guess that is the future.

 

The paper does say it uses ray tracing but does not specify it's strictly limited to RTX as far as I can tell. In theory it sounds possible to implement with a generic compute shader raytracer, but of course just because it may be possible doesn't mean that the performance is practical.

 

SSGI not true GI, HXGI - true

 

This

Raytrace mostly "just" update (bake in real time) the usual probe volume, if you have another way to query the scene visibility and radience at the probe position, that would work too (for example expensive rasterization of cubemap).

 

So I made an attempt at implementing RTXGI using cube mapping instead of raytracing. It mostly works tho there are still a few bugs in the shader code that I haven't quite had time to work out. I could post the source if anyone wants? It's not extremely usable given how slow it is to render cube maps in real time, but it could eventually be usable for static lighting or for semi-realtime lighting.

 

Hm that's certainly interesting. And yeah, real-time cubemap updates are prohibitively expensive in my experience as well, but may be acceptable in some cases I suppose.

 

Yeah, it was kinda meant as a quick little project to understand how realtime gi works rather than an attempt to make a usable asset.

I was thinking that cpu side ray-casting could be used to make things work a bit faster, however, while faster than cube mapping, it would still be too slow to actually do much in realtime (you could use maybe 50 probes at best). I think Lexie's idea of doing software raytracing on the gpu is definitely the best way, but making an efficient gpu side acceleration structure, especially one that can update itself dynamically is an enormous undertaking.

 

Indeed. Not to mention likely futile as well since raytracing APIs already are a thing and (hopefully) will one day be standard on all GPUs.

 

NO idea. but i gues sso.

I have not found any post from Lexie https://forum.unity.com/members/lexie.163359/ after september 2019 in this thread, but unity forum says he was active a few days ago in august 2022. is there any thread that says where this cool tech here went? down the drain?

 

I don't think this will never be released, on the store there is an asset very similar called upgen (https://assetstore.unity.com/packag...reen-camera-effects/upgen-lighting-urp-196955)

there are also the standard and HDRP version

 

maybe i understood wrong, but i think the tech described in this thread is different from what upgen does.