Hi all I need some help making some shapes,
I'm trying to kane an octahedron without taking a box and cutting off 
edges, as I later want to make a regular dodecahedron and an icosahedron.
I finally found the prisim and it makes good stuff for other things but 
i'm still new and cant find how to make the shapes above thanks for the 
help!

this is what I have to do ?  but remember i'm new!

#declare cutter =
box {
<2.1,2.1,2.1>
<-2.1,-2.1,-2.1>
pigment {Green}
translate  <0,3.5,0>
}

difference {

box {
<2,2,2>
<-2,-2,-2>
pigment {Green}
}
object {cutter  rotate x*45}
object {cutter  rotate x*-45}
object {cutter  rotate x*45 scale -1}
object {cutter  rotate x*-45 scale -1}


object {cutter  rotate z*45}
object {cutter  rotate z*-45}
object {cutter  rotate z*45 scale -1}
object {cutter  rotate z*-45 scale -1}
}

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Attachments:
Download 'shapes for conn.bmp.dat' (226 KB)

did the pic work It didnt on my end when I tried to use it so here it is 
again
srry all

Flaming Monarch wrote:

> Hi all I need some help making some shapes,
> I'm trying to kane an octahedron without taking a box and cutting off 
> edges, as I later want to make a regular dodecahedron and an icosahedron.
> I finally found the prisim and it makes good stuff for other things but 
> i'm still new and cant find how to make the shapes above thanks for the 
> help!
> 
> this is what I have to do ?  but remember i'm new!
> 
> #declare cutter =
> box {
> <2.1,2.1,2.1>
> <-2.1,-2.1,-2.1>
> pigment {Green}
> translate  <0,3.5,0>
> }
> 
> difference {
> 
> box {
> <2,2,2>
> <-2,-2,-2>
> pigment {Green}
> }
> object {cutter  rotate x*45}
> object {cutter  rotate x*-45}
> object {cutter  rotate x*45 scale -1}
> object {cutter  rotate x*-45 scale -1}
> 
> 
> object {cutter  rotate z*45}
> object {cutter  rotate z*-45}
> object {cutter  rotate z*45 scale -1}
> object {cutter  rotate z*-45 scale -1}
> }

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Attachments:
Download 'tetrahedron.jpg' (18 KB)

Preview of image 'tetrahedron.jpg'

I could see the first pic no problem.

I confess I have no idea how your box approach is working. The way I'd suggest
doing a regular octahedron is with plane intersections like this:

intersection {
    plane { < 1, 1, 1>, 1 }
    plane { < 1, 1,-1>, 1 }
    plane { < 1,-1, 1>, 1 }
    plane { < 1,-1,-1>, 1 }
    plane { <-1, 1, 1>, 1 }
    plane { <-1, 1,-1>, 1 }
    plane { <-1,-1, 1>, 1 }
    plane { <-1,-1,-1>, 1 }
}

8 planes to describe an 8 sided solid :)

Hope this helps.

--
Tek
http://www.evilsuperbrain.com


Flaming Monarch <fla### [at] gatescom> wrote in message
news:3C9### [at] gatescom...
> did the pic work It didnt on my end when I tried to use it so here it is
> again
> srry all
>
> Flaming Monarch wrote:
>
> > Hi all I need some help making some shapes,
> > I'm trying to kane an octahedron without taking a box and cutting off
> > edges, as I later want to make a regular dodecahedron and an icosahedron.
> > I finally found the prisim and it makes good stuff for other things but
> > i'm still new and cant find how to make the shapes above thanks for the
> > help!
> >
> > this is what I have to do ?  but remember i'm new!
> >
> > #declare cutter =
> > box {
> > <2.1,2.1,2.1>
> > <-2.1,-2.1,-2.1>
> > pigment {Green}
> > translate  <0,3.5,0>
> > }
> >
> > difference {
> >
> > box {
> > <2,2,2>
> > <-2,-2,-2>
> > pigment {Green}
> > }
> > object {cutter  rotate x*45}
> > object {cutter  rotate x*-45}
> > object {cutter  rotate x*45 scale -1}
> > object {cutter  rotate x*-45 scale -1}
> >
> >
> > object {cutter  rotate z*45}
> > object {cutter  rotate z*-45}
> > object {cutter  rotate z*45 scale -1}
> > object {cutter  rotate z*-45 scale -1}
> > }
>
>


--------------------------------------------------------------------------------

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My box aproach was made by using the difference of the cutters and a 
main box

Tek wrote:

> I could see the first pic no problem.
> 
> I confess I have no idea how your box approach is working. The way I'd suggest
> doing a regular octahedron is with plane intersections like this:
> 
> intersection {
>     plane { < 1, 1, 1>, 1 }
>     plane { < 1, 1,-1>, 1 }
>     plane { < 1,-1, 1>, 1 }
>     plane { < 1,-1,-1>, 1 }
>     plane { <-1, 1, 1>, 1 }
>     plane { <-1, 1,-1>, 1 }
>     plane { <-1,-1, 1>, 1 }
>     plane { <-1,-1,-1>, 1 }
> }
> 
> 8 planes to describe an 8 sided solid :)
> 
> Hope this helps.
> 
> --
> Tek
> http://www.evilsuperbrain.com
> 
> 
> Flaming Monarch <fla### [at] gatescom> wrote in message
> news:3C9### [at] gatescom...
> 
>>did the pic work It didnt on my end when I tried to use it so here it is
>>again
>>srry all
>>
>>Flaming Monarch wrote:
>>
>>
>>>Hi all I need some help making some shapes,
>>>I'm trying to kane an octahedron without taking a box and cutting off
>>>edges, as I later want to make a regular dodecahedron and an icosahedron.
>>>I finally found the prisim and it makes good stuff for other things but
>>>i'm still new and cant find how to make the shapes above thanks for the
>>>help!
>>>
>>>this is what I have to do ?  but remember i'm new!
>>>
>>>#declare cutter =
>>>box {
>>><2.1,2.1,2.1>
>>><-2.1,-2.1,-2.1>
>>>pigment {Green}
>>>translate  <0,3.5,0>
>>>}
>>>
>>>difference {
>>>
>>>box {
>>><2,2,2>
>>><-2,-2,-2>
>>>pigment {Green}
>>>}
>>>object {cutter  rotate x*45}
>>>object {cutter  rotate x*-45}
>>>object {cutter  rotate x*45 scale -1}
>>>object {cutter  rotate x*-45 scale -1}
>>>
>>>
>>>object {cutter  rotate z*45}
>>>object {cutter  rotate z*-45}
>>>object {cutter  rotate z*45 scale -1}
>>>object {cutter  rotate z*-45 scale -1}
>>>}
>>>
>>
> 
> 
> --------------------------------------------------------------------------------
> 
> 
> 
> 
> 
> 
>

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Cool I never thought of that way with the intersecting planes and stuff.
it worked and the code was tonnes shorter here is the way it loooked
the blue one is yours and the green mine

Tek wrote:

> I could see the first pic no problem.
> 
> I confess I have no idea how your box approach is working. The way I'd suggest
> doing a regular octahedron is with plane intersections like this:
> 
> intersection {
>     plane { < 1, 1, 1>, 1 }
>     plane { < 1, 1,-1>, 1 }
>     plane { < 1,-1, 1>, 1 }
>     plane { < 1,-1,-1>, 1 }
>     plane { <-1, 1, 1>, 1 }
>     plane { <-1, 1,-1>, 1 }
>     plane { <-1,-1, 1>, 1 }
>     plane { <-1,-1,-1>, 1 }
> }
> 
> 8 planes to describe an 8 sided solid :)
> 
> Hope this helps.
> 
> --
> Tek
> http://www.evilsuperbrain.com
> 
> 
> Flaming Monarch <fla### [at] gatescom> wrote in message
> news:3C9### [at] gatescom...
> 
>>did the pic work It didnt on my end when I tried to use it so here it is
>>again
>>srry all
>>
>>Flaming Monarch wrote:
>>
>>
>>>Hi all I need some help making some shapes,
>>>I'm trying to kane an octahedron without taking a box and cutting off
>>>edges, as I later want to make a regular dodecahedron and an icosahedron.
>>>I finally found the prisim and it makes good stuff for other things but
>>>i'm still new and cant find how to make the shapes above thanks for the
>>>help!
>>>
>>>this is what I have to do ?  but remember i'm new!
>>>
>>>#declare cutter =
>>>box {
>>><2.1,2.1,2.1>
>>><-2.1,-2.1,-2.1>
>>>pigment {Green}
>>>translate  <0,3.5,0>
>>>}
>>>
>>>difference {
>>>
>>>box {
>>><2,2,2>
>>><-2,-2,-2>
>>>pigment {Green}
>>>}
>>>object {cutter  rotate x*45}
>>>object {cutter  rotate x*-45}
>>>object {cutter  rotate x*45 scale -1}
>>>object {cutter  rotate x*-45 scale -1}
>>>
>>>
>>>object {cutter  rotate z*45}
>>>object {cutter  rotate z*-45}
>>>object {cutter  rotate z*45 scale -1}
>>>object {cutter  rotate z*-45 scale -1}
>>>}
>>>
>>
> 
> 
> --------------------------------------------------------------------------------
> 
> 
> 
> 
> 
> 
>

Post a reply to this message

Attachments:
Download 'two of em.jpg' (18 KB)

Preview of image 'two of em.jpg'

In article <3c913ee9$1@news.povray.org>, "Tek" <tek### [at] evilsuperbraincom> 
wrote:

> I confess I have no idea how your box approach is working. The way 
> I'd suggest doing a regular octahedron is with plane intersections 
> like this:
...snip...
> 8 planes to describe an 8 sided solid :)

Note that POV has no idea how to bound this, so it is completely 
unbounded...POV will test against it for every ray traced. This isn't 
much of a problem just for one, but if you use a large number of them 
you should use an appropriate bounded_by statement.

You could also use an intersection of 2 or more boxes, which might be 
faster and won't need manual bounding as badly...POV will be able to 
come up with a bounding box, just not a perfect one.

-- 
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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The corners for the octahedron would be:
 Corner1 = <0,1,0>
Corner2 = <1,0,0>
Corner3 = <0,0,1>
Corner4 = <-1,0,0>
Corner5 = <0,0,-1>
Corner6 = <0,-1,0>

Just make triangles out of these. This will give you the fastest octahedron.

#mesh {
 triangle {Corner1, Corner2, Corner3}
 triangle {Corner1, Corner3, Corner4}
 triangle {Corner1, Corner4, Corner5}
 triangle {Corner1, Corner5, Corner2}
 triangle {Corner6, Corner2, Corner3}
 triangle {Corner6, Corner3, Corner4}
 triangle {Corner6, Corner4, Corner5}
 triangle {Corner6, Corner5, Corner2}
} /* end mesh */

 -Shay



 -Shay

"Flaming Monarch" <fla### [at] gatescom> wrote in message
news:3C9### [at] gatescom...

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The simplest way to make an octahedron is the intersection of two
rectangular boxes.

object {intersection {
  object {box{<-2,-1,-1>, <2,1,1>} rotate 45*x}
  object {box{<-1,-1,-2>, <1,1,2>} rotate 45*z}
  pigment {color Green}
  finish {roughness .1 specular .1} }
}

    Note that since the diagonal aspect is sqrt(2) you can take the 2's
above to 1.414 or so with the same results.  If you make it smaller than
that, it will trim the equator very nicely.  Now, two more rectangular
solids can trim the remaining 8 edges with no trouble at all.  Two solids,
one octahedron.  Four solids, one trimmed octahedron.
    For a perfectly symmetrical octahedron, scale the z axis to 1.414, for
obvious reasons.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip

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Oh, yes- once you scale the octahedron at 1.414*y, since it is perfectly
symmetrical, you can then use one more cube and trim it into a perfect
cuboctahedron like this:

// start of POV code

#declare octahedron = intersection {
  object {box{<-2,-1,-1>, <2,1,1>} rotate 45*x}
  object {box{<-1,-1,-2>, <1,1,2>} rotate 45*z}
  pigment {color Green}
  finish {roughness .1 specular .1}
}

object {intersection {
  object {octahedron scale 1.414*y }
  object {box{-1, 1} rotate 45*y pigment {color Green} finish {roughness .1
specular .1} }
} }

// end of POV code

  Note the attached image.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip

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Attachments:
Download 'Octahedr.jpg' (8 KB)

Preview of image 'Octahedr.jpg'

Wasn't it Flaming Monarch who wrote:

>Hi all I need some help making some shapes,
>I'm trying to kane an octahedron without taking a box and cutting off 
>edges, as I later want to make a regular dodecahedron and an icosahedron.
>I finally found the prisim and it makes good stuff for other things but 
>i'm still new and cant find how to make the shapes above thanks for the 
>help!

#include "shapes2.inc"
object {Octahedron}

-- 
Mike Williams
Gentleman of Leisure

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