Attenuation types

[zahl2001]

I've been looking at the Red Book and online and can't get a clear picture of what the 3 types of lighting attenuation actually MEAN in real world terms.  Are any of the three commonly NOT used? 

Thanks,

Keith

[Orangy Tang]

If you're meaning constant/linear/exp then they're all handy. Constant means there isn't any falloff (so a light miles away is still the same strength) and is probably the least common. Linear and quadratic both have the light intensity decay over distance, which is the most intuitive behaviour for point/spot lights. Linear is easier (and hence faster) to calculate, whereas exponential is more physically accurate and looks nicer. In practice I doubt you'll see any performance difference between the two though.

Directional lights are implicitly assumed to be constant attenuation, it doesn't need to be set explicitly.

[zahl2001]

I don't know why the book couldn't have given such a clear answer... I appreciate it.

Keith