"Stephen" <mcavoys_AT_aolDOT.com> schreef in bericht 
news:web.46c4154216060248c4e49fa40@news.povray.org...
>
> Oh please don't stop posting. Peer review is always useful even if only to
> confirm what a bunch of nitpicker we are :-)
Allright. You asked for it. Here is a final WIP in pre-radiosity format, 
with all latest changes (amongst others the use of LightSys)


>>
>
> Have a book to hand.
> BTW I've kept a couple of Ken Macleod paperbacks if you want them. Now I'm
> here the postage would not signify
Hey! That would be fantastic! Thank you! I'll send you my address 
separately.

Thomas

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"Thomas de Groot" <t.d### [at] internlDOTnet> wrote:
> "Stephen" <mcavoys_AT_aolDOT.com> schreef in bericht
> news:web.46c4154216060248c4e49fa40@news.povray.org...
> >
> > Oh please don't stop posting. Peer review is always useful even if only to
> > confirm what a bunch of nitpicker we are :-)
> Allright. You asked for it. Here is a final WIP in pre-radiosity format,
> with all latest changes (amongst others the use of LightSys)
>


> >>
> >
> > Have a book to hand.
> > BTW I've kept a couple of Ken Macleod paperbacks if you want them. Now I'm
> > here the postage would not signify
> Hey! That would be fantastic! Thank you! I'll send you my address
> separately.
>






Stephen

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Shay wrote:

> 
> How about sphere_sweeps for column and flutes? Evaluating the spline
> functions would give any circumference you need.
> 


I am not really sure there is support for an interpolated or function 
driven reduction of the radius in the sphere_sweep syntax but I have 
only ever looked at it briefly. In any case I still would not be able to 
compose such a function.

So I'll take a look. Of course I can improvise my own.  (I guess I do 
that sort of thing a lot an so was hoping for some other way.)  Since 
you prodded me with this post, though, I will probably improvise 
something with spheres and cones along a spline.  I'll build the spline 
using the trace function and sample the sphere surface after it is 
already scaled.  I'll do it just to see how it works.

But constructing the thing in mesh is far and away the pragmatic 
approach, it now seems obvious.

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Thomas de Groot wrote:


> I think now that an easier workflow would be to slice a pie section from a 
> featureless shaft, exactly covering one flute width and twice the half rib 
> widths; to craft the flute and finally to apply a rotational sweep to 
> restore the complete shaft.
>

Thanks for that.  Probably how I will proceed.



> 
>>>If you want to follow the classical rules, number and form of the flutes 
>>>are fixed, but that is another discussion entirely.
>>
>>I would be intereseted if you have any references.  Right now I am using 
>>18 flutes, so a 20 degree rotation.
> 
> 24 seems to have been the general use in antiquity, at least in the 
> classical period. However, older columns could have up to 48 flutes. Ribs 
> were sharp during the Doric Order period, but flat (with deeper flutes) 
> later.
> 
>>

Interesting.  I have been making counts of visible flutes on coluns here 
and there, (including the new MMA classical wing,) then doubling the 
number, but it never seems quite that many.  I will have to pay closer 
attention.

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46c5dabe$1@news.povray.org...
> Shay wrote:
>
>
>
> I am not really sure there is support for an interpolated or function 
> driven reduction of the radius in the sphere_sweep syntax but I have only 
> ever looked at it briefly. In any case I still would not be able to 
> compose such a function.
>
Does that  fit your needs?

#declare P1=.7;
#declare P2=.9;
#declare P3=1.1;
#declare P4=1.15;


#declare Shaft=
sphere_sweep {

  cubic_spline

  5,
  <0, 7.5, 0>, P1
  <0, 5.5, 0>, P2
  <0, 0, 0>,P3
  <0, -5.5, 0>,P4
  <0, -7.5, 0>, P4
  pigment {color rgb 1 }
}

 #declare Flute =
  sphere_sweep {
  cubic_spline
  5,
  <P1, 7.5, 0>, 0.1
  <P2, 5, 0>, .1
  <P3, 0, 0>, .1
  <P4, -5, 0>,.1
  <P4, -7.5, 0>, .1
pigment {color rgb 1  }
}

#declare Flutes= union{
#declare C_Flute =0;

#while (C_Flute<20)
object{Flute rotate y*18*C_Flute}
   #declare C_Flute =C_Flute+1;
#end
}
difference{
object{Shaft}
object{Flutes}
}

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M_a_r_c wrote:

Thanks, yes, the constant radius on your flutes are one of the problems 
I wanted to overcome, but obviously, tha can be adjusted by eyeball or a 
static calulation beforehand, and I now see the possibilities.  Also it 
renders much faster than my spline solution.

Post a reply to this message

46c615ec$1@news.povray.org...
> M_a_r_c wrote:
>
> Thanks, yes, the constant radius on your flutes are one of the problems I 
> wanted to overcome, but obviously, tha can be adjusted by eyeball or a 
> static calulation beforehand, and I now see the possibilities.  Also it 
> renders much faster than my spline solution.

I didn't study the greek architecture, it's a fast try at a sphere_sweep 
solution as Shay suggested :-)
I wondered wether the flute radius had to be constant or not but I see no 
problem at making it vary as a fraction of the shaft radius.
That's better I think.


#declare P1=.7;
#declare P2=.9;
#declare P3=1.6;  // Obelix nudged my elbow here ;-) just to show as flute 
radius follows shaft radius... better with 1.1
#declare P4=1.15;


#declare Shaft=
sphere_sweep {

  cubic_spline

  5,
  <0, 12.5, 0>, P1
  <0, 10.0, 0>, P2
  <0, 5, 0>,P3
  <0, 0.0, 0>,P4
  <0, -2.5, 0>, P4

}

#local N_flutes=20; //Number of flutes
#local Flute_Ratio=.95; //flute radial coverage
#local F_fctr=pi*Flute_Ratio/N_flutes;

 #declare Flute =
  sphere_sweep {
  cubic_spline
  5,
  <P1,  12.5,  0>, F_fctr*P1
  <P2,   10,   0>, F_fctr*P2
  <P3,   5,   0>, F_fctr*P3
  <P4,  0,   0>, F_fctr*P4
  <P4,  -2.5, 0>, F_fctr*P4
}

#declare Flutes= union{
#declare C_Flute =0;

#while (C_Flute<20)
object{Flute rotate y*C_Flute*360/N_flutes}
   #declare C_Flute =C_Flute+1;
#end
}
difference{
object{Shaft}
object{Flutes}
 pigment {color rgb 1 }
}

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46c6b8cb$1@news.povray.org...
Last one, I think, now radius and y coordinate declared in the same 2d 
vector
// radius and y coordinate declared in same 2d vector

#declare P1=<.7,12.5>;
#declare P2=<.9,10>;
#declare P3=<1.1,5>;
#declare P4=<1.15,0>;
#declare P5=<1.1,-2.5>;



#declare Shaft=
sphere_sweep {

  cubic_spline

  5,
  <0, P1.y, 0>, P1.x
  <0, P2.y, 0>, P2.x
  <0, P3.y, 0>, P3.x
  <0, P4.y, 0>, P4.x
  <0, P5.y, 0>, P5.x

}

#local N_flutes=25; //Number of flutes
#local Flute_Ratio=.9; //flute radial coverage
#local F_fctr=pi*Flute_Ratio/N_flutes;

 #declare Flute =
  sphere_sweep {
  cubic_spline
  5,
  <P1.x, P1.y, 0>, F_fctr*P1.x
  <P2.x, P2.y, 0>, F_fctr*P2.x
  <P3.x, P3.y, 0>, F_fctr*P3.x
  <P4.x, P4.y, 0>, F_fctr*P4.x
  <P5.x, P5.y, 0>, F_fctr*P4.x
}

Post a reply to this message

46c6c1cf$1@news.povray.org...
Ooops

 #declare Flute =
  sphere_sweep {
  cubic_spline
  5,
  <P1.x, P1.y, 0>, F_fctr*P1.x
  <P2.x, P2.y, 0>, F_fctr*P2.x
  <P3.x, P3.y, 0>, F_fctr*P3.x
  <P4.x, P4.y, 0>, F_fctr*P4.x
  <P5.x, P5.y, 0>, F_fctr*P5.x  // not F_fctr*P4.x as in previous post
 }


Marc

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M_a_r_c wrote:

> 46c6c1cf$1@news.povray.org...
> Ooops
> 
>  #declare Flute =
>   sphere_sweep {
>   cubic_spline
>   5,
>   <P1.x, P1.y, 0>, F_fctr*P1.x
>   <P2.x, P2.y, 0>, F_fctr*P2.x
>   <P3.x, P3.y, 0>, F_fctr*P3.x
>   <P4.x, P4.y, 0>, F_fctr*P4.x
>   <P5.x, P5.y, 0>, F_fctr*P5.x  // not F_fctr*P4.x as in previous post
>  }
> 
> 
> Marc 
> 
> 
Poifect!  Thanks, I am immediately switching to this method.

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