In article <39edc188@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

>   Perhaps the distance used in the calculation should not be taken from
> the current ray only, but from the total distance travelled by the ray
> sent from the camera (and bounced from reflecting objects or refracted
> from transparent objects).
>   Or would this be too hard?

The total distance travelled would be useful for other things, like the 
pigmented light source patch, but I think it would make this problem 
worse. The glow for the distance to the point would be calculated, then 
the glow using the distance to that point and the one beyond it, etc. 
And you can't calculate the total depth and then do the glow once, 
because other things will change after reflection or refraction, like 
the angle and position.
One other possible way to "fix" this would be to have it ignore 
intersections with objects, and pretend the ray always goes to infinity. 
This would be even less physically accurate, but would at least give 
consistent *looking* results.


>   Perhaps better a falloff algorithm that doesn't depend on the ray 
>   length.

From one of my previous messages:
"I will eventually have new falloff functions with adjustable falloff 
amounts which should make fade_power unnecessary."

So: size is known to be buggy, don't use it if you have objects in your 
scene. You can control the size by adjusting the brightness of the color.
The fade_power feature is known to be unrealistic with transparent or 
reflective surfaces, and I do plan on adding glow types which 
incorporate control of the falloff which will avoid the problem of 
fade_power, as soon as I figure out how.

Which is not necessarily a simple matter, since I didn't develop the 
math in the first place, and the original author is probably busy with 
Arnold, said he thought his original patch had been forgotten and that 
he had abandoned that approach. And I have little time to spare...I have 
school to waste most of my time, and I have several other projects I am 
working on.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

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