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V-man
12-13-2005, 05:22 PM
http://www.ce.chalmers.se/edu/proj/raygpu/

It's showing planar reflections and the complex shapes are raytraced as well I think. There is also a refraction example (glasswoman).
I did not read their docs but it looks interesting enough to post here.

tfpsly
12-14-2005, 02:19 AM
There is a demo program in the download section.

andras
12-14-2005, 07:14 AM
Uhh, ok, but... what's the point?? It's super slow, and it doesn't look any better than incremental image synthesis a'la OpenGL. And why did they put a naked guy in the demo?? wtf?! :confused:

SirKnight
12-14-2005, 10:29 AM
Originally posted by andras:
And why did they put a naked guy in the demo?? wtf?! :confused: I wondered the same thing. :)

-SirKnight

HellKnight
12-14-2005, 12:12 PM
I guess it's a "proof of concept" type of thing, altought first attemps for raytracing on GPUs were done two years ago AFAIK. I didn't take the time to look through the source but I guess that's one of the first ones to run completely on the GPU...

Nice demo, but there's no practical use for such a thing IMO (now)...

V-man
12-14-2005, 07:10 PM
They are comparing against software raytracers and it says it's faster than 3DMax Mentalray. Granted, Mentalray is probably not the fastest but perhaps this GPU based solution beats them all.

hmmm, didn't I post this in the shading language forum?

Yes, about 2 years ago it was demonstrated with spheres, planes, cubes, which I have attempted myself. I never tried it myself, but I knew that using NURBS, it would be possible to do organic shapes and it would fit in nicely into the shaders.
The only problem is, intersection testing against NURBS isn't cheap.

zed
12-14-2005, 07:11 PM
And why did they put a naked guy in the demo??with a very small penis i might add, if they want something impresive to model ild be only to happy to supply a photo

there wasnt much info on the site any figures on how this compares speedwise compared to it being raytraced on the cpu?

Java Cool Dude
12-14-2005, 07:53 PM
I don't know what's even more disturbing; the naked guy in the demo or zed's comment.
/shudders

Brolingstanz
12-14-2005, 08:01 PM
hey, that's not me in that picture is it? i was streaking downtown last week...had a couple of guys chasing me with a camera, and behind them were a couple of bicycle cops.

it's getting to where a man can't get naked anymore!

it'd be cool to be able to do ray-tracing with performance degradation impunity.

rgpc
12-14-2005, 08:29 PM
Originally posted by V-man:
They are comparing against software raytracers and it says it's faster than 3DMax Mentalray. Granted, Mentalray is probably not the fastest but perhaps this GPU based solution beats them all.

Yes, but does it do everything that Mental ray does?

The only benefit I can see to raytracing on the GPU is an odd type of multiprocessor support. Products like Lightwave allow you to use multiple processors to get the rendering done quicker (and Raytracing lends itself to this nicely). This means a single frame can be produced faster. However you need the hardware (Dual core CPU's are a big bonus in this respect IMO)

But if you could use the GPU to act as extra CPU's then you could have a single SLI machine with a dual core that actually behaves like a quad (or probably alot more given the pipelines in a GPU) processor box.

But, the GPU has to be able to do everything that the CPU can - and I suspect that's what kills the idea. Products like 3D Studio, Lightwave, Maya etc. have various plugins which perform all manner of functions, from Procedural Textures, to exporters (& Bakers) to deformation to image processing (Not forgetting Volumetrics, physics, lighting etc.).

Sure the GPU could be made to do most of this stuff through GLSL, but then you'd have to have one version for the CPU and one for the GPU (or a GLSL parser built into the CPU application). Then there'd be the issue of "I have 15 different plug ins which all affect this entity - how do I get the GPU to do that"? Possibly not too difficult to overcome - I don't work with GLSL so I can't say.

So while it's a nice idea I think the implementation of a product that can use this is going to be a looooong way off.

My 2c.

Zulfiqar Malik
12-14-2005, 10:21 PM
Interestingly enough, i don't see anyone commenting on the teeny weeny breasts of the lady in the screen shots :p .

Ok enough vulgarity, there might be ladies in the house ;) .

HellKnight
12-14-2005, 11:11 PM
Originally posted by Zulfiqar Malik:

... there might be ladies in the house ;)

Noooo way ;)

Zengar
12-15-2005, 01:00 AM
Originally posted by andras:
And why did they put a naked guy in the demo?? You know nothing... It's culture! It's classic!

:-D

I guess the raytracing guys generally like mikelangelo and others ;-)

Fastian
12-15-2005, 01:32 AM
Originally posted by HellKnight:

Originally posted by Zulfiqar Malik:

... there might be ladies in the house ;)

Noooo way ;) Being a little off topic here... but wasn't this discussed a few years ago here... How many Ladies are there on this forum. Can't seem to find that thread. AFAIR there were a few :)

V-man
12-15-2005, 06:08 PM
Originally posted by rgpc:
Yes, but does it do everything that Mental ray does?It's far from Mental Ray for sure.
The biggest challenge of using the GPU is that you don't have access to a huge amount of memory where you can read and write.
You can't store tons of geometry.

Notice how non of the models are textured?
Notice how my plane is but the sphere isn't?
http://www.geocities.com/vmelkon/glsl_raytracing.html

Do you think you can wrap a 2D texture around a sphere as people usually do?

I'm going to post nude chix on my site as well.

SirKnight
12-15-2005, 07:02 PM
Originally posted by V-man:
I'm going to post nude chix on my site as well.Now that's the spirit! :D

-SirKnight

zed
12-15-2005, 07:05 PM
Originally posted by V-man:
The biggest challenge of using the GPU is that you don't have access to a huge amount of memory where you can read and write.
You can't store tons of geometrysurely u can use textures to store huge amounts of data?
V-man whats the relative time differences between your glsl veriosn + the same thing done on your cpu

btw i got this rash at work today (ive taken a photo) so drop me a line if u wanna see

V-man
12-16-2005, 06:46 PM
Originally posted by zed:
surely u can use textures to store huge amounts of data?[/QB]You can't read/write freely like you do on the CPU so you have to resort to render to texture for intermediate results. Sure, a texture can hold perhaps a polygon models.
The other problem is the instruction limit count. How many tests can you do per fragment?


Originally posted by zed:
V-man whats the relative time differences between your glsl veriosn + the same thing done on your cpu[/QB]Realtime can be acheived easily in a big window (spheres and planes only). I haven't directly compared to any normal raytracers.