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Ray Tracing on a chip (yeah. again)

Posted: Tue Mar 18, 2014 9:05 pm
by ypoissant

Re: Ray Tracing on a chip (yeah. again)

Posted: Wed Mar 19, 2014 8:21 am
by Dade
Didn't Imagination acquired Caustic a while ago ? They may have integrated some of the Caustic solution in their GPUs (so it my be something not so new but it is hard to understand from the currently disclosed information).

Re: Ray Tracing on a chip (yeah. again)

Posted: Wed Mar 19, 2014 2:55 pm
by Tristan
FWIW John Carmack had this to say about it on twitter:
I am very happy with the advent of the PVR Wizard ray tracing tech. RTRT HW from people with a clue!

I had reviewed some ray tracing hardware before the PVR stuff that was laughably unsuitable to the proposed gaming applications.

Re: Ray Tracing on a chip (yeah. again)

Posted: Wed Mar 19, 2014 5:48 pm
by davepermen
raytracing would sure be useful for the oculus rift vr future. no lens-effect post processes that lead to artefacts or need much higher res rendering. just raytrace it perfectly.

one day..

edit: and the Oculus Rift DevKit 2 is ordered.. i'll get mine in july.

Re: Ray Tracing on a chip (yeah. again)

Posted: Wed Mar 19, 2014 11:10 pm
by Dade
davepermen wrote:raytracing would sure be useful for the oculus rift vr future. no lens-effect post processes that lead to artefacts or need much higher res rendering. just raytrace it perfectly.

one day..
Ruthless self-promotion: http://www.youtube.com/watch?v=QiW24tahE7I

More in topic, I have some doubt that a 150 Gflops GPU can even scratch what high-end PC GPUs are capable of, no matter of the dedicated hardware it can have.

Re: Ray Tracing on a chip (yeah. again)

Posted: Thu Mar 20, 2014 8:27 am
by davepermen
are the gigaflops for the raytracing or just the shaders?

anyways, dedicated hw can massively improve on the Efficiency of anything. and it's not an 'or' situation. just use both :)

but surely, it'll just be a first step => slow and not that great compared to what can come thanks to it.

remember the first vertex shaders being slower than running it on cpu? till your own code flooded the cpu and you noticed vertexshaders are for free.

Re: Ray Tracing on a chip (yeah. again)

Posted: Thu Mar 20, 2014 4:09 pm
by davepermen
just went trough some oculus papers. to support the fullhd oculus devkit2, you need an impressive resolution (for a sharp crisp image).

sharp rasterized 1080p oculus:
3300x1890 => 6237000 pixels

=> 6.237 Megapixels


sharp raytraced 1080p oculus:
1920x1080 => 2 circles @ radius 540 => 1832176.8355735674166714136211286 pixels

=> 1.84 Megapixels

=> raytracing would only need 30% the pixels to have an image as crisp as the rasterized one.

still, you want them smooth => at 90fps minimum

Re: Ray Tracing on a chip (yeah. again)

Posted: Thu Mar 20, 2014 10:00 pm
by Dade
davepermen wrote:are the gigaflops for the raytracing or just the shaders?
I assume it is peak performance in "useless" stuff like matrix multiplication (so it is like to be just the number of MADD instructions for second for 2). Another pretty obvious limitation is memory bandwidth (i.e. the memory bandwidth of high-end GPUs is insane compare to mobile GPUs, APU, etc.).

Re: Ray Tracing on a chip (yeah. again)

Posted: Fri Mar 21, 2014 12:57 pm
by davepermen
it seems like it's for the shaders mostly. as the raytracing unit is fixed function => flops don't really apply there that much.

essentially, the raytracer is a huge looper unit that re-feeds stuff into the shader unit again. but intersections seem fixed function, and you can feed it a scene that it stores locally to trace more rays.

seems very useful to "just do some raytracing" inside a shader where needed. a.k.a. a fully rastericed game could have a raytraced caustic effect on a table, or similar.

and as it's a mobile chip, can i get dozens of them inside one pc, please? :) 100ts even :)