Hello POV Ray community;

At the moment I'm busying myself with the source code of POV Ray since I want to
adapt it for some test purposes. During the last day, I was not able to answer
one basic question.


Let's assume the following situation in POV Ray:

- I follow a primary ray to its first intersection point (backward raytracing).

- There I compute the diffuse reflection component --> contribution A

- Then I construct the secondary ray (specular at intersection point).

- After that I follow the secondary ray to its first intersection point.

- There I calculate the diffuse reflection component --> contribution B


My question with respect to POV Ray is:

- is there any weight factor which takes into account that contribution B still
has to pass intersection point 1 to finally reach the image pixel (so weight
factor < 1 for considering some attenuation effects) or

- is the reflection of contribution B at intersection point 1 assumed to be
perfect specular (so weight factor = 1)?

As far as I can see, the weight factor computed in the function
"determine_reflectivity" is only used for testing secondary rays with respect
to the ADC value (adaptive depth control value) and not for scaling the diffuse
color contribution derived at intersection point 2.


So I would assume that POV Ray just adds diffuse reflection components of
primary and secondary rays without any weighting. Am I right with this
assumption?


It would be very helpful for me, if you could answer this question.

Thank you very much.

Stefan Auer

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