Is it possible, but give the sphere a totally invisible texture in addition
to the halo, like:
texture // invisible
pigment
{
color rgbft <1.0, 1.0, 1.0, 1.0, 1.0>
}
finish
{
ambient 0.0
diffuse 0.0
}
}
The effect you describe is the hollow sphere itself showing in the
lightbeam.
Hope it helps,
Johannes.
