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1 Nov 2024 13:22:06 EDT (-0400)
  cylindrical image mapping & frequency (Message 1 to 3 of 3)  
From: Peter Duthie
Subject: cylindrical image mapping & frequency
Date: 3 Oct 2004 19:35:35
Message: <41608cc7$1@news.povray.org>
Is it possible to set the frequency of a cylindrically mapped image map 
to something other than one?

Ie, currently if I map an image bitmap to a cylinder (map_type 2), I get 
an image wrapped once around the Y axis, as documented.  However, what I 
would like to do is map the texture such that N copies wrap around the Y 
axis.

For example, lets say I have a seamless texture, and a very large 
cylinder close to the camera.  Up close the texture looks grainy, as it 
is only wrapped once about the Y axis, however as it's seamless, and the 
camera is only seeing a small portion of the surface, one could get away 
with increasing the frequency of the texture about the Y axis to 
something greater than one (and scale on the y axis appropriately).

Is this possible?  If so, how?

Regards,

Peter D.


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From: povray
Subject: Re: cylindrical image mapping & frequency
Date: 3 Oct 2004 20:52:23
Message: <ue71m0hthv0e0vkuj1lf7p7qhrbrg6g70a@4ax.com>
On Mon, 04 Oct 2004 19:36:12 +1000, Peter Duthie
<pli### [at] warlordsofbeercom> wrote:

>Is it possible to set the frequency of a cylindrically mapped image map 
>to something other than one?
>
>Ie, currently if I map an image bitmap to a cylinder (map_type 2), I get 
>an image wrapped once around the Y axis, as documented.  However, what I 
>would like to do is map the texture such that N copies wrap around the Y 
>axis.
>
>For example, lets say I have a seamless texture, and a very large 
>cylinder close to the camera.  Up close the texture looks grainy, as it 
>is only wrapped once about the Y axis, however as it's seamless, and the 
>camera is only seeing a small portion of the surface, one could get away 
>with increasing the frequency of the texture about the Y axis to 
>something greater than one (and scale on the y axis appropriately).
>
>Is this possible?  If so, how?
>

  #declare desired_frequency = 2;  // integer >= 1

  pigment {
    image_map {
      tga "whatever.tga"
    }
    scale <1/desired_frequency, 1, 1>
    warp { cylindrical }
  }


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From: Peter Duthie
Subject: Re: cylindrical image mapping & frequency
Date: 4 Oct 2004 17:09:15
Message: <4161bbfb$1@news.povray.org>
Thanks, that worked quite nicely.

Peter D.

pov### [at] almostbestwebnet wrote:
> 
>   #declare desired_frequency = 2;  // integer >= 1
> 
>   pigment {
>     image_map {
>       tga "whatever.tga"
>     }
>     scale <1/desired_frequency, 1, 1>
>     warp { cylindrical }
>   }
> 
>


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