Hi,

I'm trying to render a simple script:

polygon { 5, <15.45085, 0, 47.55283>, <15.11321, -3.212412, 47.55283>,
<24.45369, -5.197792, 43.30127>, <25, 0, 43.30127>, <15.45085, 0, 47.55283>
texture { pigment { color rgb <1, 0, 0> } } }

sky_sphere { pigment { color rgb <1, 1, 1> } }
camera { look_at <15, -3, 47> location <0, 0, 100> }
light_source { <0, 0, 100> color rgb <1, 1, 1> }


The red polygon is not visible. Any ideas why?

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On 11/29/24 18:20, folkert wrote:
> Hi,
> 
> I'm trying to render a simple script:
> 
> polygon { 5, <15.45085, 0, 47.55283>, <15.11321, -3.212412, 47.55283>,
> <24.45369, -5.197792, 43.30127>, <25, 0, 43.30127>, <15.45085, 0, 47.55283>
> texture { pigment { color rgb <1, 0, 0> } } }
> 
> sky_sphere { pigment { color rgb <1, 1, 1> } }
> camera { look_at <15, -3, 47> location <0, 0, 100> }
> light_source { <0, 0, 100> color rgb <1, 1, 1> }
> 
> 
> The red polygon is not visible. Any ideas why?
> 

The polygon is set up as a 2D object sitting in an x,y plane somewhere 
along z.

The normal way to specify it is to use 2D vectors of <x,y> or <u,v> 
values.

You can specify 3 coordinates, but the z values must all be the same. If 
not, the parser is supposed to issue an error because the polygon code 
won't work. However, it looks like that checking got dropped at some point.

I see this as a parser bug.

Bill P.

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> The polygon is set up as a 2D object sitting in an x,y plane somewhere
> along z.

Ah ok!
Thanks for clarifying. Do you know if there's an other way of defining
polygon-alike structures in povray?

> I see this as a parser bug.

I'll submit an issue in github.

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hi,

"folkert" <fol### [at] vanheusdencom> wrote:
> > The polygon is set up as a 2D object sitting in an x,y plane somewhere
> > along z.
>
> Ah ok!
> Thanks for clarifying. Do you know if there's an other way of defining
> polygon-alike structures in povray?

POV-Ray does have (pretty decent) documentation, see eg:
<https://wiki.povray.org/content/Reference:Polygon>
<https://wiki.povray.org/content/Documentation:Contents>

hth.


regards, jr.

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> > > The polygon is set up as a 2D object sitting in an x,y plane somewhere
> > > along z.
> >
> > Ah ok!
> > Thanks for clarifying. Do you know if there's an other way of defining
> > polygon-alike structures in povray?
>
> POV-Ray does have (pretty decent) documentation, see eg:
> <https://wiki.povray.org/content/Reference:Polygon>
> <https://wiki.povray.org/content/Documentation:Contents>

That doesn't tell me how to go from a 3D polygon to something PovRay
understands.

But for now I triangulate my polygons and put them in a mesh2 object.

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hi,

"folkert" <fol### [at] vanheusdencom> wrote:
> > > > The polygon is set up as a 2D object sitting in an x,y plane somewhere
> > > > along z.
> > >
> > > Ah ok!
> > > Thanks for clarifying. ...
> That doesn't tell me how to go from a 3D polygon to something PovRay
> understands.
> But for now I triangulate my polygons and put them in a mesh2 object.

"language barriers" :-)  polygon, the dictionary tells me:
1. (geometry) A plane figure bounded by edges that are all straight lines.

you, otoh, appear to be talking "polyhedron":
1. (geometry) A solid figure with many flat faces and straight edges.

mesh2 seems a good choice.


regards, jr.

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