> > Thanks for that..but I could not locate the equation in the
documentation - hence my need for the artificial setup.  I'm not too
familiar with the more subtle features of POVRAY - so I'd welcome an example
of the 'slope' pattern method you suggest - what about texturing a lens with
the coating I described?


After consideration, I'm not sure if slope will give you the effect you are
looking for.
The slope pattern is only affected by the surface normal relative to a
specified vector.  This could help give different reflectivity models to
different parts of the lens but wouldn't affect the individual
reflectivities.

Perhaps if you can describe more accurately what you are looking for, we can
arrive at the solution you need.

As for the variable reflection model, you can look at it this way:
reflection{
  min
  max
  falloff exp
}

min is the amount of reflection when the angle of incidence is 0deg
max is the amount of reflection when the angle of incidence is 90deg
falloff is how the reflection values vary between 0 and 90, i.e., linear,
square, cubic, etc.

Therefore your equation would be:

r(ang)= (ang/90*(max-min))^exp

where r(ang) = reflectivity at angle ang (in degrees)

this, of course, doesn't apply to the fresnel reflection model (actually it
could, but I just don't know)

-tgq

Post a reply to this message