*** TRIGGER WARNING ***

Matt Parker (Stand Up Maths) has a new video about a "self-righting"
tetrahedron:

https://www.youtube.com/watch?v=b6S5gHjuN48

But wait ...

                 ........... what's that?!!!

He provides not one but TWO .stl files . . .












                                        ... IN ASCII!   :O

The free, open-source provision of these easily downloadable, viewable,
interpretable, and 3D-printable files is not only sure to send shockwaves
throughout the POV-Ray newsgroups, but some joker is actually claiming that such
files bear more thana passing resemblance to . . . the POV-Ray mesh {} format!

Incredible!   Preposterous!
Simultaneously a blasphemous, heretical, and seditious utterance!
Home-coded find/replace extremism!

<Monty Python>
Paradoxically, those that find the _non-binary_ form of this file offensive are
- - - hateful bigots!
</Monty Python>

Ni!

- BE

Post a reply to this message

Attachments:
Download 'heppes tetrahedron.png' (157 KB)

Preview of image 'heppes tetrahedron.png'

On 09.09.2025 2:32, Bald Eagle wrote:

I'm sorry but I don't get the joke (well, it's only 6:26 here and I'm 
still waiting for my coffee to extract). So, text files may be converted 
to text files. We already seen it here with DXF converter by yesbird 
<sya### [at] gmailcom>, and DXFs are definitely more unhuman than STL 
(at least it took me about 5 minutes to read STL specs when I was 
writing STL export for my img2mesh, and DXF specs took whole day just to 
find damn chirality reference). So?

>                                          ... IN ASCII!   :O
> 
> The free, open-source provision of these easily downloadable, viewable,
> interpretable, and 3D-printable files is not only sure to send shockwaves
> throughout the POV-Ray newsgroups, but some joker is actually claiming that such
> files bear more thana passing resemblance to . . . the POV-Ray mesh {} format!
> 
> Incredible!   Preposterous!
> Simultaneously a blasphemous, heretical, and seditious utterance!
> Home-coded find/replace extremism!
> 
> <Monty Python>
> Paradoxically, those that find the _non-binary_ form of this file offensive are
> - - - hateful bigots!
> </Monty Python>
> 
> Ni!
> 
> - BE
> 

-- 
Ilyich the Toad
https://dnyarri.github.io/

Post a reply to this message

Ilya Razmanov <ily### [at] gmailcom> wrote:

> I'm sorry but I don't get the joke (well, it's only 6:26 here and I'm
> still waiting for my coffee to extract).

It's now 6:24 here, and I'm in the exact same situation.  :D

> So?

It's another installment in the long-running desire to have native stl support
for POV-Ray.  There was some insistence that .stl is a binary-only format, or
that it would be difficult to adapt our mesh {} code to handle stl.

https://news.povray.org/web.65818958d9619d9a1f9dae3025979125%40news.povray.org

So the point is that if the SDL and stl are virtually identical, then it ought
to be fairly simple to add the ability _in source_ to #include "MyModel.stl"

- BE

Post a reply to this message

On 10.09.2025 13:27, Bald Eagle wrote:
> 
> It's another installment in the long-running desire to have native stl support
> for POV-Ray.  There was some insistence that .stl is a binary-only format, or
> that it would be difficult to adapt our mesh {} code to handle stl.

STL may exist in binary form (although I see no good reason for that. 
Ok, some people say binary file takes less resources to load but I doubt 
it - I suppose most resources would be taken by interpreted scene 
itself, not the file), but ASCII STLs are fully legal. Like I said, 
beside POV-Ray output, for my img2mesh

https://dnyarri.github.io/img2mesh.html

I wrote ASCII STL, OBJ and DXF exports as well, and, imho, DXF is worst 
of all of them. It seems like developers were simply adding stuff like 
"ok let's plug this in ok so what type the variables are ah hell with 
that". What as to STL, about the only problem seem to be that some 
things declared as necessary are actually redundant and not used by 
various software, and it's hard to predict other software opinion about 
that. Well, with binary STL there would be problem with debugging 
(text-based formats are obviously the best for that), but since data are 
supposed to be the same as for ASCII, and STL allow only quite limited 
subset of what POV-Ray may do, I don't think it's an existential problem.

-- 
Ilyich the Toad
https://dnyarri.github.io/

Post a reply to this message

"Bald Eagle" <cre### [at] netscapenet> wrote:
> Ilya Razmanov <ily### [at] gmailcom> wrote:
>
> > I'm sorry but I don't get the joke (well, it's only 6:26 here and I'm
> > still waiting for my coffee to extract).
>
> It's now 6:24 here, and I'm in the exact same situation.  :D
>
> > So?
>
> It's another installment in the long-running desire to have native stl support
> for POV-Ray.  There was some insistence that .stl is a binary-only format, or
> that it would be difficult to adapt our mesh {} code to handle stl.
>
> https://news.povray.org/web.65818958d9619d9a1f9dae3025979125%40news.povray.org
>
> So the point is that if the SDL and stl are virtually identical, then it ought
> to be fairly simple to add the ability _in source_ to #include "MyModel.stl"
>
> - BE

#declare VertexVec = array[100] {
    <8,0,0> <9.44122,11.8709,0> <2.70223,19.3541,0>
    <-8.09808,18.1865,0> <-13.0913,7.48319,0> <-9.58918,-5.47232,0>
    <-5.40192,-13.8564,0> <-3.63688,-15.7569,0> <-0.826068,-10.2846,0>
    <4,-3.91887e-15,0> <7.53209,0,1.28558> <8.99892,11.4998,1.58634>
    <2.55384,18.5125,2.34791> <-7.51319,17.1735,3.21394>
<-11.7988,7.01274,3.7792>
    <-8.21366,-5.47232,3.7792> <-4.23215,-13.8564,3.21394>
<-2.7823,-15.7569,2.34791>
    <-0.248686,-10.2846,1.58634> <4.46791,-3.91887e-15,1.28558>
<6.3473,0,1.96962>
    <7.87898,10.5601,2.43042> <2.17809,16.3816,3.59721>
<-6.0322,14.6083,4.92404>
    <-8.52589,5.82151,5.79006> <-4.73074,-5.47232,5.79006>
<-1.27016,-13.8564,4.92404>
    <-0.618457,-15.7569,3.59721> <1.2133,-10.2846,2.43042>
<5.6527,-3.91887e-15,1.96962>
    <5,0,1.73205> <6.60543,9.49143,2.13727> <1.75081,13.9583,3.16333>
    <-4.34808,11.6913,4.33013> <-4.80411,4.46689,5.0917>
<-0.7701,-5.47232,5.0917>
    <2.09808,-13.8564,4.33013> <1.84218,-15.7569,3.16333>
<2.8758,-10.2846,2.13727>
    <7,-3.91887e-15,1.73205> <4.12061,0,0.68404> <5.77417,8.79393,0.844075>
    <1.47192,12.3767,1.2493> <-3.24884,9.78742,1.7101>
<-2.37489,3.58272,2.01087>
    <1.81502,-5.47232,2.01087> <4.29654,-13.8564,1.7101>
<3.44825,-15.7569,1.2493>
    <3.96092,-10.2846,0.844075> <7.87939,-3.91887e-15,0.68404>
<4.12061,0,-0.68404>
    <5.77417,8.79393,-0.844075> <1.47192,12.3767,-1.2493>
<-3.24884,9.78742,-1.7101>
    <-2.37489,3.58272,-2.01087> <1.81502,-5.47232,-2.01087>
<4.29654,-13.8564,-1.7101>
    <3.44825,-15.7569,-1.2493> <3.96092,-10.2846,-0.844075>
<7.87939,-3.91887e-15,-0.68404>
    <5,0,-1.73205> <6.60543,9.49143,-2.13727> <1.75081,13.9583,-3.16333>
    <-4.34808,11.6913,-4.33013> <-4.80411,4.46689,-5.0917>
<-0.7701,-5.47232,-5.0917>
    <2.09808,-13.8564,-4.33013> <1.84218,-15.7569,-3.16333>
<2.8758,-10.2846,-2.13727>
    <7,-3.91887e-15,-1.73205> <6.3473,0,-1.96962> <7.87898,10.5601,-2.43042>
    <2.17809,16.3816,-3.59721> <-6.0322,14.6083,-4.92404>
<-8.52589,5.82151,-5.79006>
    <-4.73074,-5.47232,-5.79006> <-1.27016,-13.8564,-4.92404>
<-0.618457,-15.7569,-3.59721>
    <1.2133,-10.2846,-2.43042> <5.6527,-3.91887e-15,-1.96962>
<7.53209,0,-1.28558>
    <8.99892,11.4998,-1.58634> <2.55384,18.5125,-2.34791>
<-7.51319,17.1735,-3.21394>
    <-11.7988,7.01274,-3.7792> <-8.21366,-5.47232,-3.7792>
<-4.23215,-13.8564,-3.21394>
    <-2.7823,-15.7569,-2.34791> <-0.248686,-10.2846,-1.58634>
<4.46791,-3.91887e-15,-1.28558>
    <8,0,-4.89859e-16> <9.44122,11.8709,-6.04464e-16>
<2.70223,19.3541,-8.94654e-16>
    <-8.09808,18.1865,-1.22465e-15> <-13.0913,7.48319,-1.44003e-15>
<-9.58918,-5.47232,-1.44003e-15>
    <-5.40192,-13.8564,-1.22465e-15> <-3.63688,-15.7569,-8.94654e-16>
<-0.826068,-10.2846,-6.04464e-16>
    <4,-3.91887e-15,-4.89859e-16>
  }

#declare NormalVec = array[100] {
    <0.970398,-0.241511,0> <0.964518,0.264016,0> <0.338788,0.940863,0>
    <-0.600834,0.799374,0> <-0.99802,0.0629003,0> <-0.940787,-0.338999,0>
    <-0.865497,-0.500914,-1.16282e-16> <0.615314,-0.788282,6.5167e-17>
<0.899878,-0.436142,5.59569e-17>
    <0.961129,-0.2761,0> <0.751627,-0.193101,0.63069>
<0.782153,0.176031,0.597703>
    <0.306739,0.711273,0.632456> <-0.439771,0.628692,0.641364>
<-0.779063,0.0397155,0.625686>
    <-0.734709,-0.283085,0.616494> <-0.686809,-0.44291,0.576301>
<0.50335,-0.753823,-0.422361>
    <0.712277,-0.368035,-0.597672> <0.748144,-0.214917,-0.627767>
<0.173444,-0.0485249,0.983648>
    <0.250024,-0.0325129,0.967694> <0.212934,0.135699,0.967597>
<0.00249393,0.200893,0.97961>
    <-0.173347,0.0312182,0.984366> <-0.172656,-0.106756,0.97918>
<-0.167243,-0.269104,0.948479>
    <0.13505,-0.628609,-0.765906> <0.171168,-0.168396,-0.970744>
<0.173433,-0.0498214,-0.983585>
    <-0.494052,0.153785,0.855723> <-0.477882,-0.198973,0.855592>
<0.0681164,-0.513488,0.855389>
    <0.552115,-0.217784,0.804822> <0.557043,0.152347,0.816391>
<0.494296,0.150612,0.856147>
    <0.499687,-0.035358,0.865484> <-0.460527,-0.389434,-0.797657>
<-0.498203,0.0846973,-0.862914>
    <-0.494921,0.142174,-0.857228> <-0.896097,0.301054,0.326153>
<-0.927261,-0.21252,0.308257>
    <-0.0705502,-0.937584,0.340527> <0.888954,-0.364892,0.276793>
<0.911329,0.307808,0.273375>
    <0.885942,0.33336,0.322456> <0.932562,0.122959,0.339425>
<-0.926214,-0.168767,-0.337114>
    <-0.911208,0.244351,-0.331652> <-0.90722,0.260614,-0.330201>
<-0.896097,0.301054,-0.326153>
    <-0.927261,-0.21252,-0.308257> <-0.0705502,-0.937584,-0.340527>
<0.888954,-0.364892,-0.276793>
    <0.911329,0.307808,-0.273375> <0.885942,0.33336,-0.322456>
<0.932562,0.122959,-0.339425>
    <-0.926214,-0.168767,0.337114> <-0.911208,0.244351,0.331652>
<-0.90722,0.260614,0.330201>
    <-0.494052,0.153785,-0.855723> <-0.477882,-0.198973,-0.855592>
<0.0681164,-0.513488,-0.855389>
    <0.552115,-0.217784,-0.804822> <0.557043,0.152347,-0.816391>
<0.494296,0.150612,-0.856147>
    <0.499687,-0.035358,-0.865484> <-0.460527,-0.389434,0.797657>
<-0.498203,0.0846973,0.862914>
    <-0.494921,0.142174,0.857228> <0.173444,-0.0485249,-0.983648>
<0.250024,-0.0325129,-0.967694>
    <0.212934,0.135699,-0.967597> <0.00249393,0.200893,-0.97961>
<-0.173347,0.0312182,-0.984366>
    <-0.172656,-0.106756,-0.97918> <-0.167243,-0.269104,-0.948479>
<0.13505,-0.628609,0.765906>
    <0.171168,-0.168396,0.970744> <0.173433,-0.0498214,0.983585>
<0.751627,-0.193101,-0.63069>
    <0.782153,0.176031,-0.597703> <0.306739,0.711273,-0.632456>
<-0.439771,0.628692,-0.641364>
    <-0.779063,0.0397155,-0.625686> <-0.734709,-0.283085,-0.616494>
<-0.686809,-0.44291,-0.576301>
    <0.50335,-0.753823,0.422361> <0.712277,-0.368035,0.597672>
<0.748144,-0.214917,0.627767>
    <0.970398,-0.241511,0> <0.964518,0.264016,-6.83606e-16>
<0.338788,0.940863,0>
    <-0.600834,0.799374,-9.79107e-17> <-0.99802,0.0629003,-2.37935e-16>
<-0.940787,-0.338999,-4.55888e-16>
    <-0.865497,-0.500914,-2.55819e-16> <0.615314,-0.788282,2.3623e-16>
<0.899878,-0.436142,2.47809e-16>
    <0.961129,-0.2761,3.22825e-16>
  }

#declare FacesIndices = array[162]{
    <0,1,11> <10,0,11> <1,2,12> <11,1,12> <2,3,13> <12,2,13>
    <3,4,14> <13,3,14> <4,5,15> <14,4,15> <5,6,16> <15,5,16>
    <6,7,17> <16,6,17> <7,8,18> <17,7,18> <8,9,19> <18,8,19>
    <10,11,21> <20,10,21> <11,12,22> <21,11,22> <12,13,23> <22,12,23>
    <13,14,24> <23,13,24> <14,15,25> <24,14,25> <15,16,26> <25,15,26>
    <16,17,27> <26,16,27> <17,18,28> <27,17,28> <18,19,29> <28,18,29>
    <20,21,31> <30,20,31> <21,22,32> <31,21,32> <22,23,33> <32,22,33>
    <23,24,34> <33,23,34> <24,25,35> <34,24,35> <25,26,36> <35,25,36>
    <26,27,37> <36,26,37> <27,28,38> <37,27,38> <28,29,39> <38,28,39>
    <30,31,41> <40,30,41> <31,32,42> <41,31,42> <32,33,43> <42,32,43>
    <33,34,44> <43,33,44> <34,35,45> <44,34,45> <35,36,46> <45,35,46>
    <36,37,47> <46,36,47> <37,38,48> <47,37,48> <38,39,49> <48,38,49>
    <40,41,51> <50,40,51> <41,42,52> <51,41,52> <42,43,53> <52,42,53>
    <43,44,54> <53,43,54> <44,45,55> <54,44,55> <45,46,56> <55,45,56>
    <46,47,57> <56,46,57> <47,48,58> <57,47,58> <48,49,59> <58,48,59>
    <50,51,61> <60,50,61> <51,52,62> <61,51,62> <52,53,63> <62,52,63>
    <53,54,64> <63,53,64> <54,55,65> <64,54,65> <55,56,66> <65,55,66>
    <56,57,67> <66,56,67> <57,58,68> <67,57,68> <58,59,69> <68,58,69>
    <60,61,71> <70,60,71> <61,62,72> <71,61,72> <62,63,73> <72,62,73>
    <63,64,74> <73,63,74> <64,65,75> <74,64,75> <65,66,76> <75,65,76>
    <66,67,77> <76,66,77> <67,68,78> <77,67,78> <68,69,79> <78,68,79>
    <70,71,81> <80,70,81> <71,72,82> <81,71,82> <72,73,83> <82,72,83>
    <73,74,84> <83,73,84> <74,75,85> <84,74,85> <75,76,86> <85,75,86>
    <76,77,87> <86,76,87> <77,78,88> <87,77,88> <78,79,89> <88,78,89>
    <80,81,91> <90,80,91> <81,82,92> <91,81,92> <82,83,93> <92,82,93>
    <83,84,94> <93,83,94> <84,85,95> <94,84,95> <85,86,96> <95,85,96>
    <86,87,97> <96,86,97> <87,88,98> <97,87,98> <88,89,99> <98,88,99>
  }

#version 3.7;


// STL export macro
#macro WriteSTL(filename)
  #fopen STLFile filename write

  // Write STL header
  #write(STLFile, "solid POVRayMesh\n")

  // Get the number of faces
  #local NumFaces = dimension_size(FacesIndices, 1);

  // Loop through all faces
  #local i = 0;
  #while (i < NumFaces)
    // Get the three vertex indices for this face
    #local v1_idx = FacesIndices[i].x;
    #local v2_idx = FacesIndices[i].y;
    #local v3_idx = FacesIndices[i].z;

    // Get the vertices
    #local v1 = VertexVec[v1_idx];
    #local v2 = VertexVec[v2_idx];
    #local v3 = VertexVec[v3_idx];

    // Calculate face normal (cross product of two edge vectors)
    #local edge1 = v2 - v1;
    #local edge2 = v3 - v1;
    #local face_normal = vnormalize(vcross(edge1, edge2));

    // Write facet to STL file
    #write(STLFile, "  facet normal ", face_normal.x, " ", face_normal.y, " ",
face_normal.z, "\n")
    #write(STLFile, "    outer loop\n")
    #write(STLFile, "      vertex ", v1.x, " ", v1.y, " ", v1.z, "\n")
    #write(STLFile, "      vertex ", v2.x, " ", v2.y, " ", v2.z, "\n")
    #write(STLFile, "      vertex ", v3.x, " ", v3.y, " ", v3.z, "\n")
    #write(STLFile, "    endloop\n")
    #write(STLFile, "  endfacet\n")

    #local i = i + 1;
  #end

  // Write STL footer
  #write(STLFile, "endsolid POVRayMesh\n")

  #fclose STLFile
#end

// Call the macro to write the STL file
WriteSTL("mesh_output.stl")

// Optional: Display a message
#debug "STL file 'mesh_output.stl' has been created.\n"

// Create a simple scene to render (optional)
camera {
  location <20, 10, -20>
  look_at <0, 0, 0>
}

light_source {
  <30, 30, -30>
  color rgb <1, 1, 1>
}

// Render the mesh for visualization (optional)
mesh2 {
  vertex_vectors {
    dimension_size(VertexVec, 1),
    #local i = 0;
    #while (i < dimension_size(VertexVec, 1))
      VertexVec[i]
      #if (i < dimension_size(VertexVec, 1) - 1) , #end
      #local i = i + 1;
    #end
  }

  normal_vectors {
    dimension_size(NormalVec, 1),
    #local i = 0;
    #while (i < dimension_size(NormalVec, 1))
      NormalVec[i]
      #if (i < dimension_size(NormalVec, 1) - 1) , #end
      #local i = i + 1;
    #end
  }

  face_indices {
    dimension_size(FacesIndices, 1),
    #local i = 0;
    #while (i < dimension_size(FacesIndices, 1))
      FacesIndices[i]
      #if (i < dimension_size(FacesIndices, 1) - 1) , #end
      #local i = i + 1;
    #end
  }

  pigment { color rgb <0.8, 0.6, 0.4> }
  finish { ambient 0.2 diffuse 0.8 }
}

Post a reply to this message

"ingo" <nomail@nomail> wrote:

.....

Yes, yes.  That's oranges to my apples.

Download an stl file from thingaverse and show me every step of the workflow to
render that in POV-Ray.

Aint nobody got time for that.


#include "MyObject.stl"
object {MyObject pigment {rgb z}}

Even a newbie can do that and get good results.

- BE

Post a reply to this message

"Bald Eagle" <cre### [at] netscapenet> wrote:
> "ingo" <nomail@nomail> wrote:
>
> .....
>
> Yes, yes.  That's oranges to my apples.
>

Ah, misunderstood. No, the #read directive expects quoted strings, not just text
and thus fails straight away on the stl 'keywords'.

An annoyance of STL is that the number of faces is not given beforehand. Makes
declaring arrays hard or one has to do a two pass run and count faces.

A conversion script in a scripting lang is the way out.

ingo

Post a reply to this message

"ingo" <nomail@nomail> wrote:

Yeah, sorry, I'm kinda thinking one thing and typing another.
I'm using too many systems at once and hopping between them all in rapid
succession.

> An annoyance of STL is that the number of faces is not given beforehand. Makes
> declaring arrays hard or one has to do a two pass run and count faces.

But we no longer have to declare the size of an array in SDL when constructing
one, unless it's a multidimensional array.

And I'm really talking about somehow doing this in the same way that we use
image_maps.  So we'd be doing this under the hood in c++.

So the thought process is actually more that what we feed the parser through SDL
when we make a mesh {} is nearly identical to the data structure of the ASCII
stl.  And so therefor it ought to be easy to bypass converting to SDL and just
read the triangle vertices in directly from the stl file.

So, I guess it would actually be

#declare MyObject = stl {"MyObject.stl"}

Now, whether or not we create a new keyword, or spruce up the mesh {} keyword to
allow something like  #declare MyObject = mesh {stl "MyObject.stl"} is something
that would be a decision for someone with more development experience than I.

Another idea is to code the conversion script into source - because it would be
nice to convert stl to mesh and save it as a file.  And convert both mesh {} and
stl to mesh2 {}.  And to have an array automatically populated with the triangle
vertices if desired.
(I'd also like to see a similar mechanism to populate an array with rgb data
from an image map and other related finction & pigment data)

So, I can envision both:
#declare MyObject = mesh {stl "MyObject.stl" make_array MyArray}
and
#declare MyObject = mesh2 {stl "MyObject.stl" make_arrays ...}
where there would some mechanism to specify what arrays for vertices, faces, and
normals would exist.

> A conversion script in a scripting lang is the way out.

I mean, yeah - I just hate all the extra steps, and the generation of a whole
new file that takes up space next to the original stl.

#read could probably use some fixing, and we all are intimately familiar with
the long-standing need to have some sort of data-typing mechanism.

- BW

Post a reply to this message

On 10/09/2025 16:23, ingo wrote:

> 
> A conversion script in a scripting lang is the way out.
> 


I agree with you.


The wiki page shows that the structure is very simple, and I think Perl* 
is a very good candidate for this.




* : (from WIKIPEDIA) Perl was developed by Larry Wall in 1987 and STL 
was invented by the Albert Consulting Group for 3D Systems in 1987 too LOL



-- 
kurtz le pirate
compagnie de la banquise

Post a reply to this message

"Bald Eagle" <cre### [at] netscapenet> wrote:

> I mean, yeah - I just hate all the extra steps, and the generation of a whole
> new file that takes up space next to the original stl.

for the current POV-Ray situation, I'm mostly writing my own little tools "that
do things" and then call POV-Ray on the generated scene. The opposite of POV-Ray
should be able to do it "all". Although I would like the latter,

ingo

Post a reply to this message