On Thursday 06 June 2002 22:09, you wrote:
> Message: 1
> Date: Thu, 30 May 2002 23:07:46 -0000
> From: "elendar_k5" <eLendar@...>
> Subject: Hardware accelerated raytracing
>
> Hi all.
>
> I'm quite new to rtrt, though I've been in the list for some months
> now. Anyway, I think I should introduce myself a bit, since it's my
> first post.
> My name is Oscar Peñas. I'm a computer science student, and I have
> some demoscene background, so I prefer the scener point of view of
> rtrt, though I don't discard other approaches.
>
> I was messing around with some ideas lately about the possibility of
> implementing a raytracer using the acceleration of modern cards,
> like
> for example letting opengl do the zbuffer stuff to get a preview of
> which objects are more likely to be intersected by primary rays.
> I am willing to know your thoughts to this respect. Do you think
> it's
> possible? What are the possibilities?


You could use an item buffer to get "exactly" which objects the
primary rays intersect. This has been done and gives a good
performance gain. But... for very simple scenes (Demo Scene
purposes), the overhead of reading from the frame-buffer will
prob. nullify the advantage. For complex scenes, the number and
complexity of solving the nth generation rays (n>1) would make the
result non-interactive.
>
> Btw, say I want to use opengl's depth buffer. Is there any way of
> accessing the depth buffer memory space to manipulate its values
> directly?


You can certainly read it and clear it, I don't know why you would
want to write to it. Besides, look up Item Buffers. They're great.

> See ya.
> ________________________________________________________________________
>
> Message: 2
> Date: Wed, 05 Jun 2002 16:44:52 -0000
> From: "quartzy75" <wally@...>
> Subject: Re: Hardware accelerated raytracing
>
> >I was messing around with some ideas lately about the possibility
> >of
>
> >implementing a raytracer using the acceleration of modern cards,
> >like
>
> > for example letting opengl do the zbuffer stuff to get a preview
> > of
> > which objects are more likely to be intersected by primary rays.
> > I am willing to know your thoughts to this respect. Do you think
>
> it's
>
> > possible? What are the possibilities?
>
> Check out this one: http://graphics.stanford.edu/papers/rtongfx/
> Still gotta look wether what they use is in Opengl2 already...


They're using neither. The ray-tracer is implemented on a simulator
for hardware which does not (but probably soon will) exist.
Great paper.

> Anyone can tell? Tim?
>
> Sincerely
> Piero


Cheers..