"Chris B" <nom### [at] nomailcom> wrote:
> "mone" <mon### [at] alienenterprisesde> wrote in message
> news:web.4ad518671466e24f66e6d7c00@news.povray.org...

> The main control on the slope pattern is a vector defining the orientation
> of the pattern. I used   'slope{z}'  in the example, along with a
> pigment_map which tells it that, everything aligned precisely with the
> z-axis is to be White with a tiny bit of transparency. It transitions to
> have progressively more transparency and a Blue color for surfaces that are
> not precisely aligned to the z-axis. It fades to completely transparent for
> surfaces at right angles to the z-axis.

That does sound logical. However I wonder how you have figured out the correct
values, so it does look so good :).


>If you declare variables 'MyLocation' and 'MyLook_At' for the camera,
> then you can simply use  slope{MyLook_At-MyLocation}  to keep the pattern
> oriented towards the camera as you move the camera around (remembering not
> to rotate objects after applying the texture/pattern).

Yes. Thank you for the information, it was very helpful. I think the reason
because it didn't work at first was because I use to put the camera in the -z
direction. And than when the slope pigment is in the +z-direction everything is
much too bright and does not look like an x-ray texture at all. But when putting
"-z" behind slope everything looks fine. Likewise, when the camera is sitting in
the -z direction it seems to work whith MyLocation-MyLook_At  instead
MyLook_At-MyLocation.
I've tried both, with the slope pigment texture you suggested (I think I've
added a bit more ambient) and aoi, it looks both quite Ok, I think (see image
below), only with aoi it started to look strange when I tried to make it more
transparent.  I think it does work too, though, if people know how to use it
correctly, only I couldn't figure it out any better with my usual
trial-error-approach. :)

Best Regards,

Simone

//////////////////////////////////////
#version unofficial megapov 1.1;

#include "Brain_POV_geom.inc" //Geometry

#declare cam_location=  <0.0, 0.0, -18.0>  ;
#declare cam_look_at=  <0.0, 0.0, 0>  ;


camera {
  location  cam_location   angle 30
  look_at  cam_look_at
  right     x*image_width/image_height
}


#declare XRayTexture2 = texture {
  pigment {
    slope{cam_location-cam_look_at}
    pigment_map {
      [0    color rgbt 2*<1,1,1,0.1>]
      [0.75 color rgbt <0.1,0.6,2,1>*1]
      [1    color rgbt <1,1,1,1>]
    }
  }
  finish {ambient 3}
}


 #declare Brain_  = object {
 object { Brain_   Center_Trans (Brain_  , x+y+z)}
 }  ;


object{
      Brain_
 scale <.6,.6,.6>
 rotate <0,180,0>
 translate <-2,0,0>
 texture {XRayTexture2 }
}


object{
      Brain_
 scale <.6,.6,.6>
 rotate <0,180,0>
 translate <2,0,0>
texture {
    pigment {
        aoi
        color_map {[0 rgb 0]
                   [.5 rgbt <0.3, 0.35, 1,.5>*1]
                   [1 rgbt <1, 1, 1,1>*1]
        }
    }
    finish { ambient 4 diffuse 0}
}

}

////////////////////////////////////

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