Wasn't it Tony who wrote:
>Help!
>
>In my current POVray work, I'm incorporating a lightning bolt - to do this
>I'm using a GIF image textured onto a very thin box primitive, and using
>'transmit' to filter out the various shades..the trouble is, the colours
>that need to be completely transparent, just...well...aren't.
>
>What happens is that I get my bright lightning bolt, fair enough...but the
>part that needs to be completely transparent just looks a little darker.
>
>I've tried pretty much everything to eliminate this problem, as you can see
>from the snippet below:
>
>#declare lightning1 = box {<0,0,0>, <2,-5,0.0001> texture {pigment
>{image_map {gif "lightning1.gif" transmit 0, 0.1 transmit 1, 0.5 transmit
>2,0.6 transmit 3,0.7 transmit 4,0.8 transmit 5,0.9 transmit 6,0.95 transmit
>7,1.0 transmit 8,1.0 transmit 9,1.0 transmit 10, 1.0 transmit 11, 1.0
>transmit 12, 1.0 transmit 13, 1.0  transmit 14, 1.0  transmit 15, 1.0
>interpolate 4} scale 2.25 scale y*1.25}} interior {fade_power 0
>fade_distance 0} finish {ambient 1.0  diffuse 0} hollow no_shadow}
>
>Any help will be very much appreciated - this is making me lose a lot of
>hair!!!!!!!
>
>BTW - is there any way to compact/refine this particular piece of script?
>Looks kind of ugly to me.

It would be an awful lot easier to turn your gif into a png and give it
an alpha channel. Your code would then reduce to:

#declare lightning1 = box {<0,0,0>, <2,-5,0.0001>
  texture {
    pigment {
      image_map {png "lightning1.png" interpolate 4}
      scale 2.25 scale y*1.25}
    }
    finish {ambient 1.0  diffuse 0}
  }
  no_shadow
}

-- 
Mike Williams
Gentleman of Leisure

Post a reply to this message