[Bf-cycles] "Is SSS ray" output and ray visibility

Greg Zaal gregzzmail at gmail.com
Sat Jan 17 17:03:48 CET 2015

Yep, Matt is right.

Clearly I don't understand anything about SSS - all I want is to be able to
prevent a light from affecting SSS shaders by disabling the SSS ray
visibility on the lamp object (so that it can only affect glossy shaders
and nothing else).

On 17 January 2015 at 16:42, Matthew Heimlich <matt.heimlich at gmail.com>

> I think what Greg is going for is a lamp that would only affect glossy
> materials, for artistic highlights on eyes and such. Currently this is
> impossible because there's no way to turn off the influence of a lamp on a
> material with SSS. So it's not so much a request for turning off the SSS of
> the material, but rather the influence of the individual lamp.
> On Sat, Jan 17, 2015 at 9:33 AM, Sergey Sharybin <sergey.vfx at gmail.com>
> wrote:
>> That's probably possible, but sounds a bit malformed. Internally SSS ray
>> only exists in medium with SSS shader and used for light attenuation in the
>> medium. From this point of view SSS ray visibility makes no sense sine
>> disabling it would basically mean removing SSS closure from the object.
>> That's not what you want i bet.
>> So main question is what you consider SSS ray.
>> Is it any ray after subsurface transmission as SSS ray? This is somewhat
>> weird for scenes when having multiple SSS objects, especially when having
>> smoke.
>> Or is it first bounce after SSS transmission as a SSS ray? In this case
>> you wouldn't be able to make SSS ignoring reflected light.
>> What's the real-life example of such a setup you're trying to achieve?
>> (assuming Cycles is more or less physical based your setup seems a bit
>> weird :)
>> On Sat, Jan 17, 2015 at 6:51 PM, Greg Zaal <gregzzmail at gmail.com> wrote:
>>> Hey folks :)
>>> Is it possible to have a Ray Visibility switch for SSS, and possibly an
>>> "Is SSS ray" output for the light path node too? Or possibly just combine
>>> it with the Diffuse ray.
>>> Why would this help?
>>>    - At the moment it's impossible to have a light that only influences
>>>    glossy rays - artists sometimes like to control their specular highlights
>>>    separately (e.g. make them more prominent in the eyes) without affecting
>>>    the rest of the lighting. If you have no SSS shaders, you can just disable
>>>    everything except glossy in the Ray Visibility panel - but if you do have
>>>    some SSS, it is doomed to be lit as well.
>>>    See here: http://i.imgur.com/n2bNWvp.png - one red light underneath
>>>    that influences everything, and one blue light above that's only supposed
>>>    to influence glossy (sphere materials left to right: diffuse, glossy,
>>>    glass, SSS)
>>>    - I wrote a light manager add-on that is able to "turn off" the
>>>    World lighting temporarily by disabling all the Ray Visibility switches.
>>>    Sure this is a hacky solution, but it's more reliable than fiddling with
>>>    the nodes.
>>> So yeah - is this even possible? And if so, who I do I have to buy beer
>>> for to make it happen? :)
>>> Cheers,
>>> Greg
>>> _______________________________________________
>>> Bf-cycles mailing list
>>> Bf-cycles at blender.org
>>> http://lists.blender.org/mailman/listinfo/bf-cycles
>> --
>> With best regards, Sergey Sharybin
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