I made an image pretty much like this one in 2004. I went on to some more
complex things, but this one somehow became an unofficial personal brand. I use
it on websites like GitHub where I for whatever reason elect not to use a photo
as my profile picture. Occasionally, I log in somewhere I haven't been for a
while and am surprised to see I'd been there before and left this image.
I wanted to rebuild this from over 20 years ago just to see if I still have the
trig chops. The answer to that is ... maybe. I know more now, and I've written
thousands of lines of "scaffolding" around vector math in the last 20 years, and
I can interrogate 3 AIs in my code editor ... but I needed all of it. I've got
more knowledge and better tools, but my intuition for this kind of 3d
manipulation has diminished.
But the bigger problem may be that I have more of a desire to write re-usable
code, which is a massive time sink. Back when I was doing POV-Ray, I solved a
lot of problems on paper, then threw away the paper. My old POV code is brimming
with "magic numbers". In a way, my approach was better then: I "kept my eyes on
the prize."
That being said, it's pretty much the same as the original, and it's still hand
coded and it was fun. I even made a version with a 14-pass "shader" just like we
used to do. The one here is just lighting.
"Shay" <nomail@nomail> wrote:
Really nice job!
Is this a "compound of 5 tetrahedra"?
Did you work out the cutouts on the tetrahedra yourself?
Are all of the facets made by CSG, or is it a "mesh" or collection of triangles
of some sort?
- BE
"Bald Eagle" <cre### [at] netscapenet> wrote:
> "Shay" <nomail@nomail> wrote:>> Really nice job!>> Is this a "compound of 5 tetrahedra"?>> Did you work out the cutouts on the tetrahedra yourself?> Are all of the facets made by CSG, or is it a "mesh" or collection of triangles> of some sort?>> - BE
Thank you.
- Yes, it is a compound of 5 tetrahedra.
- Yes, I worked out the cutouts myself.
- No CSG. This is all hand-coded mesh. All these decades later, I still don't
have the patience to wait for CSG. It would be doable as an intersection of
planes, but I still remember downloading an old IRTC entry of blue houses that
were all intersections of planes. Took FOREVER to render.
Found it: https://www.irtc.org/ftp/pub/stills/2002-08-31/golonls2.jpg
From: ingo
Subject: Re: Rebuilding an old scene from 2004
Date: 26 Aug 2026 01:54:04
Message: <6a8e7f7c$1@news.povray.org>
On 2026-08-26 05:04, Shay wrote:
> All these decades later, I still don't> have the patience to wait for CSG.
especially for csg with planes and all kind of complex shape
intersections, bounded_by can be quite a speedup.
ingo
ingo <ing### [at] nomailcom> wrote:
> On 2026-08-26 05:04, Shay wrote:> > All these decades later, I still don't> > have the patience to wait for CSG.>> especially for csg with planes and all kind of complex shape> intersections, bounded_by can be quite a speedup.>> ingo
In many cases, yes. But here, most of the bounds would overlap. And since the
shapes are not strictly convex, you'd be dealing with a lot of intersections of
intersections of planes. And you'd also probably have to minimize or eliminate
coincident edges to eliminate rendering errors ...
You might even surpass the number of triangles.
hi,
"Shay" <nomail@nomail> wrote:
> ingo <ing### [at] nomailcom> wrote:> > On 2026-08-26 05:04, Shay wrote:> > > All these decades later, I still don't> > > have the patience to wait for CSG.> >> > especially for csg with planes and all kind of complex shape> > intersections, bounded_by can be quite a speedup.> >> In many cases, yes. But here, most of the bounds would overlap. And since the> shapes are not strictly convex, you'd be dealing with a lot of intersections of> intersections of planes. And you'd also probably have to minimize or eliminate> coincident edges to eliminate rendering errors ...>> You might even surpass the number of triangles.
give my 'Bounder()' macro a try ? does sound like an "ideal case" :-).
<wiki.povray.org/content/User:Jr>
regards, jr.
"jr" <cre### [at] gmailcom> wrote:
> hi,>> "Shay" <nomail@nomail> wrote:> > ingo <ing### [at] nomailcom> wrote:> > > On 2026-08-26 05:04, Shay wrote:> > > > All these decades later, I still don't> > > > have the patience to wait for CSG.> > >> > > especially for csg with planes and all kind of complex shape> > > intersections, bounded_by can be quite a speedup.> > >> > In many cases, yes. But here, most of the bounds would overlap. And since the> > shapes are not strictly convex, you'd be dealing with a lot of intersections of> > intersections of planes. And you'd also probably have to minimize or eliminate> > coincident edges to eliminate rendering errors ...> >> > You might even surpass the number of triangles.>> give my 'Bounder()' macro a try ? does sound like an "ideal case" :-).> <wiki.povray.org/content/User:Jr>>>> regards, jr.
Nothing is more "POV-Ray" than a link to a zip file on a wiki instead of a
GitHub repo. There's still a culture around here that hasn't changed in decades.
It's great to see how it has endured.
I can see what your macro is doing, and it would work for bounding boxes, but
bounding boxes are a poor fit over any tetrahedron, and the bounding boxes would
in this case all overlap across most of the geometry.
And that would be a lot of geometry. Each tetrahedron face is built like a
compressed, beveled cube. A cube like that is an intersection of 26 planes. Now
extrude that across an L shaped path and the numbers start going up fast,
especially since many of the planes used to construct the cube would have to be
intersected themselves to keep them from colliding with other parts along the
path.
It would be straightforward with a series of macros, but there's no way around
being slow.
"Cousin Ricky" <rickysttATyahooDOTcom> wrote:
> "Shay" <nomail@nomail> wrote:> >> > - No CSG. This is all hand-coded mesh. ...>> Hand-coded mesh? And I thought I was a masochist!
I've done it before on a few occasions, simply because for special instances, it
does turn out to be easier.
"Cousin Ricky" <rickysttATyahooDOTcom> wrote:
>> Hand-coded mesh? And I thought I was a masochist!
This is POV-Ray. Everyone here is a masochist!
FWIW, this isn't even scraping the masochism surface. I've done so much worse in
POV-Ray.
"Shay" <nomail@nomail> wrote:
Hi,
That’s a really nice render of the compound of five tetrahedra — thank you for
sharing it.
I especially appreciate the work you put into editing the mesh by hand. Getting
the intersections to look clean without automated CSG or a pre-made library is
no small task, and it shows. The classic “five tetrahedra” compound always looks
deceptively simple until you actually try to build it.
I’ve been a bit obsessed with the same figure myself. Over the past months I
designed and published a few physical LEGO versions on BrickLink, in different
sizes and with different edge thicknesses (some more “wireframe”, some more
rigid). If anyone here also enjoys brick-built geometry, here they are:
https://www.bricklink.com/v3/studio/design.page?idModel=802912https://www.bricklink.com/v3/studio/design.page?idModel=799698https://www.bricklink.com/v3/studio/design.page?idModel=840837
I also have a small Python script that starts from a single base tetrahedron and
applies the right rotations and colours to generate the full compound. I’d be
happy to share it if anyone finds it useful.
Thanks again for posting this — it’s always a pleasure to see this old favourite
treated with care in POV-Ray.
Best regards,
B. Gimeno
P.S. If anyone feels that links to another platform, or models rendered in
another program, have nothing to do with POV-Ray… they probably haven’t been
hooked on the same program for more than twenty years. Without that
long-standing obsession I would never have ended up building this thing in
physical bricks.
So, I cannot see parts of this reply, presumably due to UTF-8/non-ASCII
characters, and when I tried to use Thunderbird it said "connection refused."
Is this a website policy change, or something that I need to fix in my
Thunderbird application?
- BE
From: Jim Henderson
Subject: Re: Rebuilding an old scene from 2004
Date: 1 Sep 2026 12:31:15
Message: <6a96fdd3$1@news.povray.org>
On Tue, 1 Sep 2026 11:43:18 EDT, Bald Eagle wrote:
> So, I cannot see parts of this reply, presumably due to UTF-8/non-ASCII> characters, and when I tried to use Thunderbird it said "connection> refused."
The Thunderbird issue is probably due to the NNTP server name change that
happened a couple of weeks ago. It used to be news.povray.org, but now
uses a prefix of "nntp" instead of "news".
--
"I learned long ago, never to wrestle with a pig. You get dirty, and
besides, the pig likes it." - George Bernard Shaw
From: William F Pokorny
Subject: Re: Rebuilding an old scene from 2004
Date: 1 Sep 2026 12:42:13
Message: <6a970065$1@news.povray.org>
On 9/1/26 11:43, Bald Eagle wrote:
> So, I cannot see parts of this reply, presumably due to UTF-8/non-ASCII> characters, and when I tried to use Thunderbird it said "connection refused."> > Is this a website policy change, or something that I need to fix in my> Thunderbird application?> > - BE
Ref:
https://news.povray.org/povray.general/thread/%3Cweb.6a772e1743a59e128139023aa597fb8%40news.povray.org%3E/
For Thunderbird I went with:
"...changing to nntp.povray.org in the connection settings should work."
Bill P.
From: Chris Cason
Subject: Re: Rebuilding an old scene from 2004
Date: 3 Sep 2026 08:23:26
Message: <6a9966be@news.povray.org>
On 2/09/2026 01:43, Bald Eagle wrote:
> So, I cannot see parts of this reply, presumably due to UTF-8/non-ASCII> characters, and when I tried to use Thunderbird it said "connection refused."> > Is this a website policy change, or something that I need to fix in my> Thunderbird application?
If you are referring to text missing after the word "that" in line 3 of the post you
are replying to, it should not happen when viewing the NG via NNTP in Thunderbird
itself.
There was an issue viewing it in the web view, though.
The part that reads "That’s a really nice render of the compound of five tetrahedra
— thank you for sharing it." had two characters that were not being handled when the
message was being rendered as UTF-8. These are the chars 0x92 at offset 0x26 and 0x97
at offset 0x61.
00000000 22 53 68 61 79 22 20 3c 6e 6f 6d 61 69 6c 40 6e |"Shay" <nomail@n|
00000010 6f 6d 61 69 6c 3e 20 77 72 6f 74 65 3a 0a 48 69 |omail> wrote:.Hi|
00000020 2c 0a 54 68 61 74 92 73 20 61 20 72 65 61 6c 6c |,.That.s a reall|
00000030 79 20 6e 69 63 65 20 72 65 6e 64 65 72 20 6f 66 |y nice render of|
00000040 20 74 68 65 20 63 6f 6d 70 6f 75 6e 64 20 6f 66 | the compound of|
00000050 20 66 69 76 65 20 74 65 74 72 61 68 65 64 72 61 | five tetrahedra|
00000060 20 97 20 74 68 61 6e 6b 20 79 6f 75 20 66 6f 72 | . thank you for|
Both of these represent undefined codepoints in UTF-8 and the result of passing them
through the PHP htmlentities() function with the options that were in the code before
was to cause the text between the two points to vanish.
There's been a number of complaints about this behavior so I did spend some time today
trying to at least get it to not disappear the text, and it does appear to work now,
though the characters in question are replaced by default glyphs.
The proper fix is to convert each message to UTF-8 according to its declared encoding
(we do store this in the DB along with the message), but I don't have time to do that
right now so what's there will have to do. I have been working on the webview code
recently (RSS and sitemaps) and this matters for those, too, so it should get fixed in
the not too distant future.
FWIW see three attachments: one with the old behavior, one with the current, and one
with what it would look like with the codepage taken into account.
-- Chris
Chris Cason <del### [at] deletethistoopovrayorg> wrote:
> There's been a number of complaints about this behavior so I did spend some time
today trying to at least get it to n
ot disappear the text, and it does appear to work now, though the characters in
question are replaced by default glyphs
.
Thanks! That's much better.
I'll fix my Thunderbird the next time I get a chance to sit and catch a breath.
- BW
From: Jim Henderson
Subject: Re: Rebuilding an old scene from 2004
Date: 3 Sep 2026 14:05:02
Message: <6a99b6ce$1@news.povray.org>
Hi, Chris!
FWIW, using the Pan newsreader that I've used for years, what I see most
closely resembles the second screenshot - some of the punctuation shows up
as an unknown unicode character.
Pan has been around for a long time, and was written to comply with a NNTP
standard called GNKSA.
The default encoding it uses is UTF-8.
--
"I learned long ago, never to wrestle with a pig. You get dirty, and
besides, the pig likes it." - George Bernard Shaw
"Shay" <nomail@nomail> wrote:
I am pretty sure I remember the original post for this (I think you may have
asked people to guess how it was made but that could apply to any number of your
images as they are often complex in nature and way beyond my math skills).
Great to see you back in the POV saddle, hoping to join you again one day soon
when life slows down.
Ahh, .zip files my favourite source control method.
From: Chris Cason
Subject: Re: Rebuilding an old scene from 2004
Date: 4 Sep 2026 23:23:09
Message: <6a9b8b1d$1@news.povray.org>
On 4/09/2026 13:38, Dave Blandston wrote:
> "Shay" <nomail@nomail> wrote:>> This is POV-Ray. Everyone here is a masochist!> > I don't feel alone anymore. Thank you.https://news.ycombinator.com/item?id=40643207
From: Chris Cason
Subject: Re: Rebuilding an old scene from 2004
Date: 4 Sep 2026 23:23:10
Message: <6a9b8b1e$1@news.povray.org>
This is what I thought the internet would become, back in the 1990s, just tons of projects like Povray. Not addictive dark pattern trillionaires, see the recent Eli Gray article posted on HN how big tech enables link fraud for example. This was before FAANG existed as it does now. Apple was a struggling PC maker and Microsoft was the evil empire being challenged by a Finnish college student. Sun and SGI and DEC were big tech and they made you know... actual tech. It was this crazy dream that it would last like that forever, that the internet would just be one huge BBS of Povray style people, makers and users, who were interested in art and science above all else. Nobody was thinking you could contract third parties of poor people to screen out death videos on your BBS so they would have PTSD but you could make billions. Nobody was thinking to clickfarm children.
"Shay" <nomail@nomail> wrote:
>> This is POV-Ray. Everyone here is a masochist!
Ouh yes :)
The last few days I have asked myself countless times:
What nonsense am I working on again ...
Ma
Chris Cason <del### [at] deletethistoopovrayorg> wrote:
> https://news.ycombinator.com/item?id=40643207
The early years of POV-Ray was an exciting time. There were many people working
on companion software (modelers, animation tools, et cetera). Maybe part of the
attraction of continuing to use POV-Ray, for me at least, is the psychological
link to the past.
"B. Gimeno" <nomail@nomail> wrote:
> "Shay" <nomail@nomail> wrote:> Hi,> That�s a really nice render of the compound of five tetrahedra � thank you for> sharing it.> I especially appreciate the work you put into editing the mesh by hand. Getting> the intersections to look clean without automated CSG or a pre-made library is> no small task, and it shows. The classic �five tetrahedra� compound always looks> deceptively simple until you actually try to build it.> I�ve been a bit obsessed with the same figure myself. Over the past months I> designed and published a few physical LEGO versions on BrickLink, in different> sizes and with different edge thicknesses (some more �wireframe�, some more> rigid). If anyone here also enjoys brick-built geometry, here they are:>> https://www.bricklink.com/v3/studio/design.page?idModel=802912> https://www.bricklink.com/v3/studio/design.page?idModel=799698> https://www.bricklink.com/v3/studio/design.page?idModel=840837>> I also have a small Python script that starts from a single base tetrahedron and> applies the right rotations and colours to generate the full compound. I�d be> happy to share it if anyone finds it useful.> Thanks again for posting this � it�s always a pleasure to see this old favourite> treated with care in POV-Ray.>> Best regards,> B. Gimeno>>> P.S. If anyone feels that links to another platform, or models rendered in> another program, have nothing to do with POV-Ray� they probably haven�t been> hooked on the same program for more than twenty years. Without that> long-standing obsession I would never have ended up building this thing in> physical bricks.
That is great stuff! If anyone else wants to play around with this, I think
these are the required vertices and transformations. Not tested, but pasted
together from various files that work.
/* Coordinate values for a tetrahedron inside a dodecahedron with an edge
length of 1. This will match the scale used at
https://mathworld.wolfram.com/Tetrahedron5-Compound.html. */
#local P = (sqrt(5) + 3) / 4 // Phi / DODECAHEDRON_EDGE_LENGTH
#local V = 1 / 2 // Varphi / DODECAHEDRON_EDGE_LENGTH
#local N = (sqrt(5) + 1) / 4 // 1 / DODECAHEDRON_EDGE_LENGTH
#local Tetrahedron = array[4] { <0, P, -V>, <-P, -V, 0>, <N, -N, -N>, <V, 0, P>
}
#local Triangles = array[4][3] {
{ <Tetrahedron[0], Tetrahedron[1], Tetrahedron[2] },
{ <Tetrahedron[0], Tetrahedron[2], Tetrahedron[3] },
{ <Tetrahedron[0], Tetrahedron[3], Tetrahedron[1] },
{ <Tetrahedron[3], Tetrahedron[2], Tetrahedron[1] }
}
#local Q = P - 1
#local Transforms = array[5] {
matrix <1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0>,
matrix <Q, N, V, -N, V, -Q, -V, -Q, N, 0, 0, 0>,
matrix <-N, V, Q, -V, -Q, -N, -Q, -N, V, 0, 0, 0>,
matrix <-N, -V, -Q, V, -Q, -N, Q, -N, V, 0, 0, 0>,
matrix <Q, -N, -V, N, V, -Q, V, -Q, N, 0, 0, 0>
}
"s.day" <s.d### [at] uelacuk> wrote:
> "Shay" <nomail@nomail> wrote:>> I am pretty sure I remember the original post for this (I think you may have> asked people to guess how it was made but that could apply to any number of your> images as they are often complex in nature and way beyond my math skills).>> Great to see you back in the POV saddle, hoping to join you again one day soon> when life slows down.>> Ahh, .zip files my favourite source control method.
Thanks, oldtimer.
Chris Cason <del### [at] deletethistoopovrayorg> wrote:
> https://news.ycombinator.com/item?id=40644828>> "This is what I thought the internet would become, back in the 1990s, just tons of
projects like Povray. Not addictiv
e dark pattern trillionaires, see the recent Eli Gray article posted on HN how big
tech enables link fraud for example.
This was before FAANG existed as it does now. Apple was a struggling PC maker and
Microsoft was the evil empire being
challenged by a Finnish college student. Sun and SGI and DEC were big tech and they
made you know… actual tech. It was
this crazy dream that it would last like that forever, that the internet would just be
one huge BBS of Povray style peo
ple, makers and users, who were interested in art and science above all else. Nobody
was thinking you could contract th
ird parties of poor people to screen out death videos on your BBS so they would have
PTSD but you could make billions.
Nobody was thinking to clickfarm children."
>> -- doubloon, June 11, 2024
"Wait! what's happening here! did I miss another post explaining? ...a homepage
news article it should be!
Do we now have some special wiki-like syntax that prettyfies our mails or
quotations in them into the http view?"
-- Me Wondering , September 15, 2026
From: Chris Cason
Subject: Re: Rebuilding an old scene from 2004
Date: 17 Sep 2026 22:48:11
Message: <6aaca66b$1@news.povray.org>
On 15/09/2026 21:41, Mr wrote:
> "Wait! what's happening here! did I miss another post explaining? ...a homepage> news article it should be!
Agreed, I am planning on making it one but I've been snowed under at work (where we
are also dealing with our share of botnets).
> Do we now have some special wiki-like syntax that prettyfies our mails or> quotations in them into the http view?"
Actually ... no. Sorry :) ... this was a hard-coded exception I made on the spur of
the moment as I was working on the site's PHP code at the time. My original post
(viewable via NNTP) is plain text.
-- Chris
net> wrote:
