POV-Ray : Newsgroups : povray.binaries.images : billboard tint : Re: billboard tint Server Time
25 Feb 2024 07:31:22 EST (-0500)
  Re: billboard tint  
From: William F Pokorny
Date: 3 Nov 2023 14:57:13
Message: <65454289$1@news.povray.org>
On 11/3/23 12:49, Mike Miller wrote:
> I've run into a problem with the
> transparent portion of the png when turning on fog. The fog is tinting the
> billboard shape.

The fog feature is a faked effect which works, solely, with initial 
camera rays. More specifically fog is added using the distance from the 
camera to the first intersection - or effective infinity (2,000,000 
units?). Those initial camera rays will intersect the billboards whether 
the pigment is transparent or not.

So, I'm not surprised the bill board tint is different, but at this 
moment, I don't understand why it appears to be more foggy rather than 
less. Most probably your fog is set up to be more dense at distance (not 
ground fog)?

Maybe we'd get what you see, if using ground fog that is not oriented 
correctly? Not sure. Could be some bug too - there are some in the 
official POV-Ray code - and probably some unknown ones still in my 
playpen code too. Faked effects are tricky.

In any case, distance based features will struggle with a "billboards 
technique".

Bill P.


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