Le 18-02-11 à 09:47, William F Pokorny a écrit :
> On 01/23/2018 03:28 PM, clipka wrote:
>> Am 23.01.2018 um 16:57 schrieb William F Pokorny:
>>
> ...
>> I'd say yes, that would be quite useful indeed.
>>
>> (And maybe also `media_attenuation on` for light sources inside the
>> media container.)
>>
> 
> I have been weeks now on and off digging into media and media code. It 
> turns out there are scenes - abyss.pov for example - where the 
> light_source IS inside the media container. We get no attenuation no 
> matter other settings in those cases and often a washed out visual 
> result. I'm starting to wonder if this lack of attenuation is behind the 
> struggles with contrast in some media scenes.
> 
> Anyway, I want to immediately let folks know there is a way to get 
> media_attenuation on in cases where your light source(s) are inside your 
> media container. If you set up a difference creating either a small void 
> or small divot around your light source(s) - presto media_attenuation is 
> on.
> 
> It's an obvious idea since for lights outside the media container in my 
> original posting the attenuation is always on. Of course, the small void 
> idea didn't work when I first tried it...
> 
> Turns out in the global - the post transforms - scene coordinate space, 
> the distance from the light outside to surface of the media container 
> must be >= 0.001. This value appears to come from '#define 
> SHADOW_TOLERANCE 1.0e-3' value being used in trace.cpp, but I've not 
> spent time hacking at that code to be 100% sure.
> 
> Getting the lights outside the container >= 0.001 for attenuation works 
> all the way back to 3.6.1 in my testing.
> 
> Bill P.
> 

So, we should add :
looks_like{sphere{0, 0.001 pigment{rgbt 1}}}
to the lights that are inside some media container.

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