POV-Ray : Newsgroups : povray.general : Real Time Ray Tracing Server Time
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From: Ben Chambers
Subject: Real Time Ray Tracing
Date: 8 Mar 2002 04:07:30
Message: <3c887f52@news.povray.org>
http://www.xl3d.com/bottom.htm

I haven't looked at it yet, but it looks interesting.

...Chambers


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From:
Subject: Re: Real Time Ray Tracing
Date: 8 Mar 2002 04:20:02
Message: <l20h8us9sqrsng4tdrn8kl9h6o2mvd2prq@4ax.com>
On Fri, 8 Mar 2002 01:04:46 -0800, "Ben Chambers" <bdc### [at] yahoocom>
wrote:
> http://www.xl3d.com/bottom.htm
> I haven't looked at it yet, but it looks interesting.

AFAIK they mix terms. They write about OpenGL as raytracer but afaik OpenGL is
not a raytracer. Am I right ? I'm not an expert but this thing looks at first
sight like Moray with OpenGL preview.  Perhaps with speed improvements. I'm
sceptical :-)

ABX
--
disc{z,-z 5#macro O()asc(substr("-+((1*(,1,/.-,*/(,&.323/'1"e,1))*.1-4#declare
e=e-1;#end#local e=26;pigment{#local g=function(_){ceil(_)-_}function#local//X
k=function{pattern{object{sphere_sweep{linear_spline 13#while(e>0)<O(),O()//AB
>.01#end}}}}{k(g(atan2(x,y)),g(ln((y+x)^2+1e-5)),0)}}finish{ambient 1}}//POV35


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From: Christopher James Huff
Subject: Re: Real Time Ray Tracing
Date: 8 Mar 2002 06:16:03
Message: <chrishuff-1FA5CC.06161508032002@netplex.aussie.org>
In article <l20h8us9sqrsng4tdrn8kl9h6o2mvd2prq@4ax.com>,
 W?odzimierz ABX Skiba <abx### [at] babilonorg> wrote:

> AFAIK they mix terms. They write about OpenGL as raytracer but afaik OpenGL is
> not a raytracer. Am I right ? I'm not an expert but this thing looks at first
> sight like Moray with OpenGL preview.  Perhaps with speed improvements. I'm
> sceptical :-)

OpenGL has no built-in support for raytracing, but there is a trick 
which has to do with getting it to render a single pixel and getting the 
depth of that pixel. The result is intersection information...very 
roundabout and probably too inefficient to be useful, but I don't really 
know.
You could also use scanline rendering instead of tracing the primary 
rays, if you don't mind everything being converted to polygons. Same 
technique: use the depth buffer to find the intersection points. Barely 
something you could consider raytracing, but it accomplishes the same 
thing.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/


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From: Warp
Subject: Re: Real Time Ray Tracing
Date: 8 Mar 2002 08:58:52
Message: <3c88c39b@news.povray.org>
Ben Chambers <bdc### [at] yahoocom> wrote:
> http://www.xl3d.com/bottom.htm

> I haven't looked at it yet, but it looks interesting.

  The source of the page which that links give me is the following:

<html>
<head>
<title>**</title>
 
</head>
<body marginheight=10 marginwidth=10 topmargin=10 leftmargin=10 background="imag
es/bot-bg.gif">



</body>
</html>


  Yes, looks quite interesting.

  Besides, real-time raytracing is nothing fancy. POV-Ray can do it.

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -


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From: Thorsten Froehlich
Subject: Re: Real Time Ray Tracing
Date: 8 Mar 2002 14:23:11
Message: <3c890f9f@news.povray.org>
In article <3c88c39b@news.povray.org> , Warp <war### [at] tagpovrayorg>  wrote:

>   Besides, real-time raytracing is nothing fancy. POV-Ray can do it.

And it can do so with double precision (the mentioned code uses single
precision all the way) and something better than a few triangles and spheres
using primitive light model, for example text objects and phong shading...

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org


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From: Mahalis
Subject: Re: Real Time Ray Tracing
Date: 8 Mar 2002 15:24:37
Message: <3c891e05$1@news.povray.org>
And how can that be set up? Or is it something for version 4 (!!!) that
we're just getting a preview of in 3.5?

"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:3c890f9f@news.povray.org...
> In article <3c88c39b@news.povray.org> , Warp <war### [at] tagpovrayorg>  wrote:
>
> >   Besides, real-time raytracing is nothing fancy. POV-Ray can do it.
>
> And it can do so with double precision (the mentioned code uses single
> precision all the way) and something better than a few triangles and
spheres
> using primitive light model, for example text objects and phong shading...
>
>     Thorsten
>
> ____________________________________________________
> Thorsten Froehlich, Duisburg, Germany
> e-mail: tho### [at] trfde
>
> Visit POV-Ray on the web: http://mac.povray.org


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From: Thorsten Froehlich
Subject: Re: Real Time Ray Tracing
Date: 8 Mar 2002 15:35:02
Message: <3c892076@news.povray.org>
In article <3c891e05$1@news.povray.org> , "Mahalis" <don### [at] fakeycom>
wrote:

> And how can that be set up? Or is it something for version 4 (!!!) that
> we're just getting a preview of in 3.5?

No, just a built-in scene to demonstrate that contrary to some claims POV-Ray
is not slow.  Some scenes are simply very complex and people making the claim
a scene renders slowly because POV-Ray would be slow don't really know what
they are talking about because they are comparing it to (commercial) programs
that don't use ray-tracing or simplified forms of (pseudo) ray-tracing :-)

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org


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From:
Subject: Re: Real Time Ray Tracing
Date: 8 Mar 2002 15:36:15
Message: <au7i8u8b54vg4mduo33eb20n5kcmhfv44u@4ax.com>
On Fri, 8 Mar 2002 15:24:30 -0500, "Mahalis" <don### [at] fakeycom> wrote:
> And how can that be set up? Or is it something for version 4 (!!!) that
> we're just getting a preview of in 3.5?

It is builded in Win and Mac version. Read carefuly latest longest discussion
in povray.programming (it was there iirc). With GUI-Extensions everybody can
build its own application to real-time cooperation with povray.

ABX


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From: Warp
Subject: Re: Real Time Ray Tracing
Date: 8 Mar 2002 15:54:08
Message: <3c8924f0@news.povray.org>
Just get a fast-enough computer, make a simple scene and render it
in an animation.
  For example this scene:

camera { location -z*15 look_at 0 angle 35 }
light_source { <100,250,-50>, 1 }
union
{ sphere { -x, 1 }
  sphere { x, 1 }
  sphere { y, 1 }
  box { <-2,0,-1.5><2,-1,1.5> }
  pigment { rgb <1,.5> }
  finish { specular .5 reflection .5 }
  rotate <clock*360, 2*clock*360, .75*clock*360>
}

renders in my computer (1.2GHz Athlon) at 320x240 with +kff500 -ga -f
at about 5 FPS.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -


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From: Thorsten Froehlich
Subject: Re: Real Time Ray Tracing
Date: 8 Mar 2002 16:31:02
Message: <3c892d96@news.povray.org>
In article <3c8924f0@news.povray.org> , Warp <war### [at] tagpovrayorg>  wrote:

>   Just get a fast-enough computer, make a simple scene and render it
> in an animation.
>   For example this scene:
>
> camera { location -z*15 look_at 0 angle 35 }
> light_source { <100,250,-50>, 1 }
> union
> { sphere { -x, 1 }
>   sphere { x, 1 }
>   sphere { y, 1 }
>   box { <-2,0,-1.5><2,-1,1.5> }
>   pigment { rgb <1,.5> }
>   finish { specular .5 reflection .5 }
>   rotate <clock*360, 2*clock*360, .75*clock*360>
> }
>
> renders in my computer (1.2GHz Athlon) at 320x240 with +kff500 -ga -f
> at about 5 FPS.

Indeed, even the render windows with their slower display deliver such
framerates on fast systems today.

Of course, the demo that is built-in has a few additional features like being
thread-safe and no dependency on dynamic memory allocation.  It also uses more
appropriate bouble-buffered drawing.  The hard-coded scene allows to skip
parsing as well, also the scene currently used isn't really very simple: In
the scene description language it is less than forty lines with no fancy
constructs, but expanded in C it is over 2000 lines of structure definitions
taking about 20 KB of memory...

Oh, and before people start wondering why the POV-Team spends time on this, it
should be noted that this allows for example to uncover bugs or inefficiencies
in the source code and in addition only "playing" with some parts of the code
allow us to understand again what those who programmed it a decade ago were up
to.  In short, playing with it today allows improvements for all users in the
future :-)

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org


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