Hi all!

I have got a problem and I hope that povray could be a solution. Perhaps you
have got a suggestion for me.

Having a bunch of polygons and a ray I would like to find out how often the ray
intersects a polygon. I guess I can find out how to set up a camera to get some
rays, but i have no idea how to count the intersections... Is it possible to
define a material, so that the resulting pixel colour reflects the number of
intersections?

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Am 07.10.2014 13:42, schrieb Horst:
> Hi all!
>
> I have got a problem and I hope that povray could be a solution. Perhaps you
> have got a suggestion for me.
>
> Having a bunch of polygons and a ray I would like to find out how often the ray
> intersects a polygon. I guess I can find out how to set up a camera to get some
> rays, but i have no idea how to count the intersections... Is it possible to
> define a material, so that the resulting pixel colour reflects the number of
> intersections?

You can use a semi-transparent surface, e.g. "colour rgbt <0,0,0,0.8>", 
and a contrasting background, e.g. "colour rgb <1,1,1>"; then, the 
resulting colour will depend on how often the ray enters or exits the 
object.

Use the "File_Gamma=1.0" ini-file setting to more easily evaluate the 
result; the pixel value will then follow an exponential law:

100%   = no intersection
  80%   = 1 intersection
  64%   = 2 intersections
  51.2% = 3 intersections

etc.

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