Far and normal ranges are fine in my testing, but when you get too close it starts to shrink the glow inside sphere for some reason. :? Tried normalizing all vectors but doesn't do anything.

Could be that perspective "eye point" is not at 0 but more behind or forward some amount. Fov near plane was at least not that.

Edit: Oh i know what happens... Because of perspective view the sphere front becomes much wider than center part of sphere when zoomed close in and therefore glow will be smaller than visible sphere. Imagine looking at a cube from straight front, the front face will cover everything up when watching it closer, and it is the same thing. Solution could be scaling up the glow when coming down to certain range... just goes very unformal and tricky again. I have no idea how to calculate correct scaling and if it's worth it.