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Le 18-01-12 à 12:32, Kenneth a écrit :
> Alain <kua### [at] videotron ca> wrote:
>
>>
>> If you use fade_power 1, you get light fading as a direct factor of the
>> distance : Double the distance = half of the illumination. Works in a 2D
>> world.
>
> Thanks; that clarifies my own misconception of fade_power 1.0. For some reason,
> I always assumed that it meant NO fading of the light-- like a typical power law
> of, say,
> pow(7,1.0) = 7
For fade_power 1,
it's fade_distance/pow(Distance, 1) = fade_distance/Distance
For fade_power 0,
it becomes fade_distance/pow(Distance,0) = fade_distance/1
>
> Of course, using fade_power 1.0 in a scene DOES fade the light; I just never
> knew what that fading value represented. I think the documentation's chart
> example threw me off-- it shows a 'curve' for fade_power 1.0, where I was
> naively expecting a straight line (at some downward angle, of course.) The
> chart's X and Y axes are indeed linear-- but the X-axis represents a more
> 'compressed' set of values than the Y-axis... a detail that I never paid much
> attention to! So the 'curve' is correct. (Personally, I would have preferred a
> chart with equal values on the X and Y axes-- to show the fading behavior more
> clearly.)
>
> The one detail that's not *specifically* included in the chart is the chosen
> fade_distance-- although the documentation seems to indicate that it's also 1.0.
> Adding that to the chart itself would remove any ambiguity, IMO.
>
>
>
>
Usually, for an area_light, you want to use fade_distance = size od the
area_light.
Otherwise, you can use fade_distance 1 for large scenes or far lights,
and 0.1 or less for lights that are very close to the closest surface.
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