POV-Ray : Newsgroups : povray.general : Background Image Server Time
1 Aug 2024 04:10:25 EDT (-0400)
  Background Image (Message 1 to 5 of 5)  
From: Kaka22
Subject: Background Image
Date: 29 Apr 2006 07:45:01
Message: <web.445350c4b8907d159c45cf0f0@news.povray.org>
Is it possible to put an image (instead of a color)as a background in a
scene ?

thanks


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From: John VanSickle
Subject: Re: Background Image
Date: 29 Apr 2006 09:33:24
Message: <44536b24$1@news.povray.org>
Kaka22 wrote:
> Is it possible to put an image (instead of a color)as a background in a
> scene ?
> 
> thanks

Yes.  Apply the image to a large polygon and put the polygon in the 
background.

Regards,
John


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From: Kaka22
Subject: Re: Background Image
Date: 29 Apr 2006 10:30:00
Message: <web.445377325ecbd4a99c45cf0f0@news.povray.org>
John VanSickle <evi### [at] hotmailcom> wrote:
> Kaka22 wrote:
> > Is it possible to put an image (instead of a color)as a background in a
> > scene ?
> >
> > thanks
>
> Yes.  Apply the image to a large polygon and put the polygon in the
> background.
>
> Regards,
> John

Can you please give me a small example...because I tried:
polygon {
    4,
    <0, 0>, <0, 300>, <300, 300>, <300, 0>
    texture {
      finish { ambient 1 diffuse 0 }
      pigment { image_map { gif "test.gif"  } }
    }
  }
and the image repeats instead of having the whole picture as my background.
thanks


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From: Jim Charter
Subject: Re: Background Image
Date: 29 Apr 2006 10:43:05
Message: <44537b79$1@news.povray.org>
Kaka22 wrote:
> John VanSickle <evi### [at] hotmailcom> wrote:
> 
>>Kaka22 wrote:
>>
>>>Is it possible to put an image (instead of a color)as a background in a
>>>scene ?
>>>
>>>thanks
>>
>>Yes.  Apply the image to a large polygon and put the polygon in the
>>background.
>>
>>Regards,
>>John
> 
> 
> Can you please give me a small example...because I tried:
> polygon {
>     4,
>     <0, 0>, <0, 300>, <300, 300>, <300, 0>
>     texture {
>       finish { ambient 1 diffuse 0 }
>       pigment { image_map { gif "test.gif"  } }
>     }
>   }
> and the image repeats instead of having the whole picture as my background.
> thanks
> 
> 
> 
the image_map is scaled from <0,0> to <1,1> by default so you have to 
either

a:
scale the texture to match the size of your object


or

b:

first apply the texture to a unit sized object then scale up the object.


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From: Norbert Kern
Subject: Re: Background Image
Date: 29 Apr 2006 18:15:00
Message: <web.4453e2ee5ecbd4a9ee88888c0@news.povray.org>
Hi, use this code for the usual camera type.
You have to adapt the first lines and the name of the background image
to your scene.
If you use z direction as up, you have to change cam_s to z too.


//____________________________________________________________________________
#declare cam_loc = <0,1.5,-8>; // camera location
#declare lookat = <0,0.5,0>;   // camera look_at
#declare cam_ang = 67;         // camera angle
#declare back_dist = 1000;     // how far away the background should be
#declare cam_mirror = 1;       // 1 for normal / -1 for mirror image

#include "transforms.inc"
#declare cam_z = 0.5*image_width/image_height/tan (radians (cam_ang*0.5));
#declare cam_ang_up = degrees (2*atan2(0.5/cam_z,1));
#declare cam_a = cam_mirror*image_width/image_height;
#declare cam_s = y;
#declare cam_d = vnormalize (lookat-cam_loc);
#declare cam_r = vnormalize (vcross (cam_s,cam_d));
#declare cam_up = vnormalize (vcross (cam_d,cam_r));
#declare cam_dir = cam_d*cam_z;
#declare cam_right = cam_r*cam_a;

#declare fz = vlength (cam_dir);
#declare fx = vlength (cam_right)/2;
#declare fy = vlength (cam_up)/2;

#macro OrientZ (p1,p2,cs)          // looks like Reorient_trans macro!
        #local nz = vnormalize (p2-p1);
        #local nx = vnormalize (vcross (cs,nz));
        #local ny = vcross (nz,nx);
        matrix <nx.x,nx.y,nx.z,ny.x,ny.y,ny.z,nz.x,nz.y,nz.z,p1.x,p1.y,p1.z>
#end

camera {
        location cam_loc
        up cam_up
        right cam_right
        direction cam_dir
}
/*
camera {                        // equivalent camera definition
        location cam_loc
        right cam_right
        look_at lookat
        angle cam_ang
}
*/
//_background________________________________________________________________

box {
        <0,0,0> <1,1,0.1>
        texture {
                pigment {
                        image_map {png "sky" once map_type 0 interpolate 2}
                }
                finish {ambient 1 diffuse 0}
        }
        translate <-0.5,-0.5,0>
        scale 2*<cam_mirror*fx,fy,0.5>
        translate fz*z
        scale back_dist
        OrientZ (cam_loc,lookat,cam_up)
}
//______________________________________________________________________________


Regards
Norbert Kern


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