I modelling a spaceship with povray and want to add an imagemap
to the tail. I use

    object { tailwing
               texture {C1b}
               texture { pigment { image_map {
                 gif "altairsign.gif"
                 map_type 0
                 once
                 filter 0,1 }
                 scale <3,2,1> translate <-3,-1,0.05>}}
             translate <-7,4,-0.02>}

When rendering the imagemaps shows up on both sides of the tail, on one side it
is the mirrorimage. I understand that this is because the imagemap is considered

to be long rods in the z-direction with different colors. But is it any way to
avoid
it showing through the tail, in other words just show up on one side?

--
Tommy Grav
-------------------------------------------------------------
tom### [at] astrouiono     http://www.uio.no/~tommygr/
Institute of Astrophysics, UiO, No
IMTU tn++t4+tg+ ru+ge++ !3i jt+au+st+ls hi++dr-so++zh-sy-sw++

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Tommy Grav wrote:

> I modelling a spaceship with povray and want to add an imagemap
> to the tail. I use
> <snip>
>
> When rendering the imagemaps shows up on both sides of the tail, on one side it
> is the mirrorimage. I understand that this is because the imagemap is considered
> to be long rods in the z-direction with different colors. But is it any way to
> avoid it showing through the tail, in other words just show up on one side?
> --
> Tommy Grav

    I have had this problem before and others have asked
the same question. It wasn't until I read your post just
now that I have finaly thought of a way of avoiding this.
    You have your tail section declared. Now use a
second copy of the tail section and uniformly scale it
smaller than the original.
    Now take the second tail section and use it to CSG
the inside of the first to create a cavity inside. If the object
is solid the image map will indeed appear on the other side.
If it is hollow on the other hand it will apply properly on
just one side.
    If you try it and it works let me know. I would
like to hear about it.

Ken Tyler

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You could also try repeating the same object and translating it down a bit
then giving it the texture you want on the reverse side. Does that make
sense?
Mick

> Tommy Grav wrote:
> 
> > I modelling a spaceship with povray and want to add an imagemap
> > to the tail. I use
> > <snip>
> >
> > When rendering the imagemaps shows up on both sides of the tail, on one
side it
> > is the mirrorimage. I understand that this is because the imagemap is
considered
> > to be long rods in the z-direction with different colors. But is it any
way to
> > avoid it showing through the tail, in other words just show up on one
side?
> > --
> > Tommy Grav

> 
>

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1) Apply the image map to a super-thin object that is then placed next to the tail.

2) Or, replicate the tail as a csg without the image map and a second with the image
map.  Then place the two copies next to each other offset to the side you want the
image to appear on.  POV only has problems when the surface is exactly the same on
both... even a micro bit gives it the difference necessary to resolve the surface
without mixing the two.

Regards,
Robert J Becraft
aka cas### [at] aolcom

Tommy Grav wrote:

> I modelling a spaceship with povray and want to add an imagemap
> to the tail. I use
>
>     object { tailwing
>                texture {C1b}
>                texture { pigment { image_map {
>                  gif "altairsign.gif"
>                  map_type 0
>                  once
>                  filter 0,1 }
>                  scale <3,2,1> translate <-3,-1,0.05>}}
>              translate <-7,4,-0.02>}
>
> When rendering the imagemaps shows up on both sides of the tail, on one side it
> is the mirrorimage. I understand that this is because the imagemap is considered
>
> to be long rods in the z-direction with different colors. But is it any way to
> avoid
> it showing through the tail, in other words just show up on one side?
>
> --
> Tommy Grav
> -------------------------------------------------------------
> tom### [at] astrouiono     http://www.uio.no/~tommygr/
> Institute of Astrophysics, UiO, No
> IMTU tn++t4+tg+ ru+ge++ !3i jt+au+st+ls hi++dr-so++zh-sy-sw++

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Tommy Grav <tom### [at] astrouiono> wrote in article
<3611DF5C.190E15CE@astro.uio.no>...
> I modelling a spaceship with povray and want to add an imagemap
> to the tail.
> 
> When rendering the imagemaps shows up on both sides of the tail, on one
side it
> is the mirrorimage. I understand that this is because the imagemap is
considered
> 
> to be long rods in the z-direction with different colors. But is it any
way to
> avoid
> it showing through the tail, in other words just show up on one side?
> 

	Use a texture map, like this (untested so I may have screwed up somewhere)
:

#declare T_Tail_With_Image=
texture {C1b}
texture {
 pigment {
  image_map {
   gif "altairsign.gif"
   map_type 0
   once
   filter 0,1
  }
  scale <3,2,1> translate <-3,-1,0.05>
 }
}

object {
 tailwing
 texture {
  gradient z
  texture_map {
   [0.5 texture { C1b } ]
   [0.5 texture { T_Tail_With_Image } ]
  }
 }
 translate <-7,4,-0.02>
}

Or something like that.

HTH,
-- 
Scott Hill
Sco### [at] DDLinkscouk
Software Engineer (and all round nice guy)
Author of Pandora's Box
Company homepage : http://www.ddlinks.demon.co.uk

"The best trick the devil ever pulled was convincing people he didn't
exist..."
								- Verbal Kint.

"the Internet is here so we can waste time talking about nothing in 
 particular when we should be working" - Marcus Hill.

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Tommy Grav wrote:
> 
> I modelling a spaceship with povray and want to add an imagemap
> to the tail. I use

  <snip>

> When rendering the imagemaps shows up on both sides of the tail, on one
> side it is the mirrorimage. I understand that this is because the
> imagemap is considered to be long rods in the z-direction with different
> colors. But is there any way to avoid it showing through the tail, in
> other words just show up on one side?

What I do is make a decal object.  I use a primitive of the same shape
as the object to receive the image.  I make the image background totally
transparent (transmit 0,1 usually does the trick), clip the decal to
the boundaries of the image, apply the no_shadow flag, and place it
so that it is a small fraction above the surface of the object.  The
result is like those decals you get for model airplanes.

Regards,
John
-- 
"He has the power to rear-project major cities!" -- Mike Nelson

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Tommy Grav <tom### [at] astrouiono> writes:

> to be long rods in the z-direction with different colors. But is it any way to
> avoid
> it showing through the tail, in other words just show up on one side?

  What I'd do is cut the tail into two parts (for instance, with a
correctly placed plane) and give each half a different texture (one with
the image map and the other one without it). If your tail has a strange
shape, you'll have to replace the plane by whatever is more appropriate,
but otherwise this is the simplest solution.

Roland.
-- 
Les francophones m'appellent Roland Mas,
English speakers call me Rowlannd' Mass,
Nihongode hanasu hitoha [Lolando Masu] to iimasu.
Choisissez ! Take your pick ! Erande kudasai !

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