(Speculation)
I suspect the sky_spere is not exactly represented as an unit sphere around the
camera, but around the start of a ray (camera, reflected, refracted...) More
exactly, the returned value would be that of the pigment 1 unit away from the
origin, in the (relative) direction of the ray. Since only the direction is
important, this would give the desired result.

Margus

Nieminen Juha wrote:
> 
>   I have a question for the hardcore povrayers (I can only guess the correct
> answer, but I'm not sure about it):
> 
>   The sky sphere is a sphere of radius 1 around the camera, as I described
> in the previous article.
>   Now suppose that the camera is at the origin and a ray is shot from it in
> the z direction and it hits a reflective object at <0,0,2>. The reflected
> ray is shot in the x direction (ie. it made a 90 degrees turn). This
> reflected ray doesn't hit anything else.
>   Since it doesn't hit anything else, it is tested against the sky sphere.
> But since the sky sphere is a sphere of radius 1 at the origin, this ray
> doesn't (?) hit it.
>   How is this solved?
> 
> --
> main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
> ):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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