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David Buck <dav### [at] simberon com> wrote:
> Hey, Craig. I haven't seen you around in years.
>
> For those who don't know, Craig is the author of Practical Raytracing in C:
> "https://www.amazon.ca/Practical-Ray-Tracing-Craig-Lindley/dp/0471573019"
>
> (unless I have the wrong Craig Lindley :-) )
>
> David Buck
Wow, synchronicity - I've had that book for decades and it's down in my studio
right now. I was reading through it (and some Graphics Gems) just last weekend!
Post a reply to this message
Attachments:
Download 'practicalraytracinginc.jpg' (285 KB)
Preview of image 'practicalraytracinginc.jpg'
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David Buck <dav### [at] simberoncom> wrote:
> Hey, Craig. I haven't seen you around in years.
>
> For those who don't know, Craig is the author of Practical Raytracing in C:
> "https://www.amazon.ca/Practical-Ray-Tracing-Craig-Lindley/dp/0471573019"
>
> (unless I have the wrong Craig Lindley :-) )
>
> David Buck
>
>
> On 2022-03-29 2:54 p.m., Craig Lindley wrote:
> > Hello,
> >
> > I came across the attached image the other day that I thought was beautiful so I
> > decided to look at raytracing again. I hadn't done any raytracing since about
> > 1993 so the POVRAY program has changed quite a bit. I am using the 3.8 version
> > of POVRAY and it is amazing. I retraced one of my old images that took 33 hours
> > in the 1990's and today on my Mac it took about 10 minutes.
> >
> > Anyway. I would like to understand how this image was produced because I would
> > like to do something like it for this years Christmas card.
> >
> > It seems to be made up of Fibonacci spirals but I am not sure. I looked at the
> > POVRAY documentation for these types of spirals but I cannot seem to duplicate
> > the image accurately. I would guess that each color is its own Fibonacci spiral
> > but how they are positioned so they don't interfere with each other escapes me.
> >
> > Any help or suggestions would be appreciated. If anyone has access to the actual
> > POV file for this image I would love to have it.
> >
> > Thanks in advance.
Guilty as charged. Yes that is my book but like I said I haven't done any
raytracing in a long time. Thanks everyone for the hints on how to make this
image. Hopefully I'll get my raytracing chops back in trying to figure this
image out.
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Le 2022-03-29 à 14:54, Craig Lindley a écrit :
> Hello,
>
> I came across the attached image the other day that I thought was beautiful so I
> decided to look at raytracing again. I hadn't done any raytracing since about
> 1993 so the POVRAY program has changed quite a bit. I am using the 3.8 version
> of POVRAY and it is amazing. I retraced one of my old images that took 33 hours
> in the 1990's and today on my Mac it took about 10 minutes.
>
> Anyway. I would like to understand how this image was produced because I would
> like to do something like it for this years Christmas card.
>
> It seems to be made up of Fibonacci spirals but I am not sure. I looked at the
> POVRAY documentation for these types of spirals but I cannot seem to duplicate
> the image accurately. I would guess that each color is its own Fibonacci spiral
> but how they are positioned so they don't interfere with each other escapes me.
>
> Any help or suggestions would be appreciated. If anyone has access to the actual
> POV file for this image I would love to have it.
>
> Thanks in advance.
My proposition :
Start by constructing a single spiral and make it an object with an
union. Don't give it any pigment nor finish yet.
Next, place several copies of that object, each rotated so that it's
constituent spheres are tangent to those of the previous.
In this case, there are height spirals, so, 45° of rotation between each.
In that step, give each spiral it's own pigment and finish.
In the finish, make them reflective with the metallic attribute.
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David Buck <dav### [at] simberoncom> wrote:
> Hey, Craig. I haven't seen you around in years.
>
> For those who don't know, Craig is the author of Practical Raytracing in C:
> "https://www.amazon.ca/Practical-Ray-Tracing-Craig-Lindley/dp/0471573019"
>
> (unless I have the wrong Craig Lindley :-) )
>
> David Buck
>
>
> On 2022-03-29 2:54 p.m., Craig Lindley wrote:
> > Hello,
> >
> > I came across the attached image the other day that I thought was beautiful so I
> > decided to look at raytracing again. I hadn't done any raytracing since about
> > 1993 so the POVRAY program has changed quite a bit. I am using the 3.8 version
> > of POVRAY and it is amazing. I retraced one of my old images that took 33 hours
> > in the 1990's and today on my Mac it took about 10 minutes.
> >
> > Anyway. I would like to understand how this image was produced because I would
> > like to do something like it for this years Christmas card.
> >
> > It seems to be made up of Fibonacci spirals but I am not sure. I looked at the
> > POVRAY documentation for these types of spirals but I cannot seem to duplicate
> > the image accurately. I would guess that each color is its own Fibonacci spiral
> > but how they are positioned so they don't interfere with each other escapes me.
> >
> > Any help or suggestions would be appreciated. If anyone has access to the actual
> > POV file for this image I would love to have it.
> >
> > Thanks in advance.
David,
On a personal note, I think we met once a long time ago. If I recall correctly,
you worked for DEC in Colorado Springs. Are you still in the Springs? I live in
Rockrimmon.
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Alain Martel <kua### [at] videotronca> wrote:
> > Hello,
> >
> > I came across the attached image the other day that I thought was beautiful so I
> > decided to look at raytracing again. I hadn't done any raytracing since about
> > 1993 so the POVRAY program has changed quite a bit. I am using the 3.8 version
> > of POVRAY and it is amazing. I retraced one of my old images that took 33 hours
> > in the 1990's and today on my Mac it took about 10 minutes.
> >
> > Anyway. I would like to understand how this image was produced because I would
> > like to do something like it for this years Christmas card.
> >
> > It seems to be made up of Fibonacci spirals but I am not sure. I looked at the
> > POVRAY documentation for these types of spirals but I cannot seem to duplicate
> > the image accurately. I would guess that each color is its own Fibonacci spiral
> > but how they are positioned so they don't interfere with each other escapes me.
> >
> > Any help or suggestions would be appreciated. If anyone has access to the actual
> > POV file for this image I would love to have it.
> >
> > Thanks in advance.
>
> My proposition :
> Start by constructing a single spiral and make it an object with an
> union. Don't give it any pigment nor finish yet.
> Next, place several copies of that object, each rotated so that it's
> constituent spheres are tangent to those of the previous.
> In that step, give each spiral it's own pigment and finish.
> In the finish, make them reflective with the metallic attribute.
Yes this is what I will attempt next. I looked into the Doyle spirals as was
mentioned above but the math is challenging to say the least.
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I've lived in Ottawa since 1977 but I did work on contract in Colorado
Springs around 1994 - 1995. That's likely when we met.
David
On 2022-03-31 11:07 a.m., Craig Lindley wrote:
>
> David,
>
> On a personal note, I think we met once a long time ago. If I recall correctly,
> you worked for DEC in Colorado Springs. Are you still in the Springs? I live in
> Rockrimmon.
>
>
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On 29/03/2022 20:54, Craig Lindley wrote:
> Any help or suggestions would be appreciated. If anyone has access to the actual
> POV file for this image I would love to have it.
I made this kind of picture.
I just found this old code in my archives.
// --------------------------------------------------------------------
#declare index=0;
#declare nBilles=32; //64;
#declare dAngle=4;
#declare dRayon=0.50;
#declare rayon = 1-dRayon;
#declare xPos=0;
#declare rot=0;
#declare spirale = union {
#declare index=0;
#while(index<nBilles)
#declare rayon=rayon+dRayon;
#declare rot=rot+dAngle;
sphere {
<0,0,0>, rayon
translate xPos*x
rotate rot*y
}
#if(debugging) #debug concat("Rayon = ",str(rayon,7,2)," xPos =
",str(xPos,7,2)," Rot = ",str(rot,7,2),"\n") #end
#declare xPos=xPos+rayon;
#declare index=index+1;
#end
}
#declare theColor = rgb <0,0,0>;
#declare index=0;
#while(index<360)
#declare theColor = rgb CH2RGB(index);
object {
spirale
rotate index*y
pigment { color theColor }
}
#declare index=index+10;
#end
// --------------------------------------------------------------------
Hope that help
--
Kurtz le pirate
Compagnie de la Banquise
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hi,
kurtz le pirate <kur### [at] gmailcom> wrote:
> ...
> I made this kind of picture.
> I just found this old code in my archives.
> ...
"heavy, man. psychedelic." ;-)
regards, jr.
Post a reply to this message
Attachments:
Download 'klp.png' (578 KB)
Preview of image 'klp.png'
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"Craig Lindley" <cal### [at] gmailcom> wrote:
> Hello,
>
> I came across the attached image the other day that I thought was beautiful so I
> decided to look at raytracing again. I hadn't done any raytracing since about
> 1993 so the POVRAY program has changed quite a bit. I am using the 3.8 version
> of POVRAY and it is amazing. I retraced one of my old images that took 33 hours
> in the 1990's and today on my Mac it took about 10 minutes.
>
> Anyway. I would like to understand how this image was produced because I would
> like to do something like it for this years Christmas card.
>
> It seems to be made up of Fibonacci spirals but I am not sure. I looked at the
> POVRAY documentation for these types of spirals but I cannot seem to duplicate
> the image accurately. I would guess that each color is its own Fibonacci spiral
> but how they are positioned so they don't interfere with each other escapes me.
>
> Any help or suggestions would be appreciated. If anyone has access to the actual
> POV file for this image I would love to have it.
>
> Thanks in advance.
After struggling with Doyle circle packing code for a week I finally have an
image which is close to the original image I posted. I've attached the image and
a POV file in case anyone wants to play around with it. I wrote the circle
packing code in Java and then transferred the generated spheres into a POV file.
If anyone is interested in the Java code, let me know and I can get it to you.
Cheers
Craig Lindley
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Attachments:
Download 'spheresdoyle.png' (692 KB)
Preview of image 'spheresdoyle.png'
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"Craig Lindley" <cal### [at] gmailcom> wrote:
> Hello,
>
> I came across the attached image the other day that I thought was beautiful so I
> decided to look at raytracing again. I hadn't done any raytracing since about
> 1993 so the POVRAY program has changed quite a bit. I am using the 3.8 version
> of POVRAY and it is amazing. I retraced one of my old images that took 33 hours
> in the 1990's and today on my Mac it took about 10 minutes.
>
> Anyway. I would like to understand how this image was produced because I would
> like to do something like it for this years Christmas card.
>
> It seems to be made up of Fibonacci spirals but I am not sure. I looked at the
> POVRAY documentation for these types of spirals but I cannot seem to duplicate
> the image accurately. I would guess that each color is its own Fibonacci spiral
> but how they are positioned so they don't interfere with each other escapes me.
>
> Any help or suggestions would be appreciated. If anyone has access to the actual
> POV file for this image I would love to have it.
>
> Thanks in advance.
And here is the poverties file
Post a reply to this message
Attachments:
Download 'spheresdoyle.pov.txt' (10 KB)
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