in news:3B8F7FC3.D717E8FF@engineer.com Kari Kivisalo wrote:

> http://www.pp.htv.fi/kkivisal/prox.jpg
> 

Interesting.

Just an idea I came up with while making a short bicycle tour this 
afternoon. It may be complete nonsense.

 Shoot a ray at the object to be rendered. Put an imaginary sphere with 
a given radius with its centre on the ray, its surface should toutch 
the objects surface in the intersection point. Now check if the sphere 
intersects somewhere with the object. If so, reduce the sphere radius 
until it does not intersect anymore (the sphere should still be 
toutching the object at the intersection point).
 Now make the grey-value of the objects pigment depends on the sphere's 
radius.
 By setting limits to the sphere's sizes you could control the amount 
of patina.
 Would something like this work? As a patch? As a clever combination of 
macros and functions (3.5)?

Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/

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