wollinger nous apporta ses lumieres en ce 08/04/2006 13:38:
> Hi all,
> 
> I have a beginners Question on fog and sky handling:
> 
> I want to render a landscape in a rectangular geographic systen. That means
> that I have "translate < 419020, 0, 279020>" for my height_field, camera
> and so on. Do I also have to translate my sky and the fog? At least for the
> fog I get an warning that I can't translate the up vector. It seems that I
> dont have to do it for the fog but I get a sharp edge in the horizont where
> the fog ends. Is there a way to have ground fog and a blue sky?
> 
> tnx
> Wolfgang
> 
> my code for fog and sky:
> 
> // fog on the ground -------------
> fog { fog_type   2
>       //translate Fog_Center
>       distance   7500
>       color      rgbt <1,1,1,0.6>
>       fog_offset 700
>       fog_alt    100
>     }
> 
> sky_sphere{
>         //pigment {planar colour_map{[0,rgb <0.9,0.9,1>][1, rgb
> <0.1,0.2,1>]}}
>         pigment{P_Cloud4}
>         //pigment {rgbt <1.0,1.0,1.0,(1-clock)>}
>         //pigment {rgbt <1.0,1.0,1.0,0>}
>         scale 2 //avoid repetion
> 
>         }
> 
> 
You don't translate a sky_sphere. It's a background pigment applyed to a unit sphere
centered around 
the camera. If a ray don't encounter any object, it's reported on that sphere.
What you see at the horizon, is not the end of the fog but the end of your plane. You
can try adding 
a filtering or plain fog with a greater distance (like 8000 to 9000), smaller
fog_offset (like 70 or 
less) and fog_alt (like 20 or less). When you use a transmiting fog with a transmit
value of 0.6, 
you always get AT LEAST 60% of the background.
you can also place a plane just under your hight_field with a pattern similar to that
of the 
hight_field.

-- 
Alain
-------------------------------------------------
A true friend is someone who reaches for your hand
and touches your heart.

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