No Dan, the dist start end end dials are quite different.

Dist start tells the light when it should start to fade, and sit end tells it when it should reach an intensity of zero. The progression from one to the other is linear. For example, I could set start to 10, and end to 10.5 inches. This means that the light would be at the full intensity I have set it at from the source all the way to the 10 inch boundary, and then would rapidly diminish to zero within 0.5 inches.

This is not how real light works. A light source in the real world is at its brightest at the source (no surprise there), but begins to diminsh as soon as the light waves have left the source. It does not diminish linearly, though, it obeys the inverse square law which BB has explained perfectly eloquently in his post, so I see no need to mangle it here with my confused mumblings.

Thank you somch for coming up with this solution, BB - although I'm shocked and surprised at you that you hadn't considered this problem before! It's always been something I've noticed, but figured there was little I could do about it. I do have one question for you, however (which I will gladly wait until you have completed the AM shader before answering) - how can this be applied to infinite lights? Due to there nature, there is no co ordinate data for these light types, and so I'm not sure how we can input the x/y/z data required by this shader.

I await your reply patiently, but with bated breath. :)

JonTheCelt