I found the answer:  The problem isn't with the sphere, it is with the
sky_sphere.

The sky_sphere does not handle filtered transparency. It acts as if you
specified rgbt even if you use rgbf. If you specify both (rgbft) then the
sky_sphere adds the two values together and treats the sum as rgbt.
  So your textures were working correctly on the sphere, they were NOT
working correctly on the sky_sphere!

Examples of how sky_sphere apparently reads colors:
rgbt<0, 0, 0, 1>                   = rgbt<0, 0, 0, 1>
rgbf<0, 0, 0, 1>                   = rgbt<0, 0, 0, 1>
rgbft<0, 0, 0, 0.4, 0.6>           = rgbt<0, 0, 0, 1>
rgbft<0, 0, 0, 0.1, 0.5>           = rgbt<0, 0, 0, 0.6>

!!!

Post a reply to this message