CGTalk - SSS light linking

CharlesVarenne

10-10-2006, 02:53 PM

Hi,
I have a problem to understand about the llight linking in the sss shader.
I know you can put either 0, 1 or 2.
But what i really dont understand is that depending on the polygon model i am working on i dont have the same effect.

First model act like that: light linking 0 in the shader and 0 in the missfastlightmap make the model to appear black. Same if i put 1. It does work only if I put 2 in the lightmap and in the shader.

On my second model if I put 2 in the lightmap and in the shader the light are acting the same way as if i would put 0 in the first model.:eek:
The good setting I found was 0 in the shader and 2 in the lightmap.

It is fine to use it like that as I found the solution, but I was expecting a more logical way of working. Anyone get a clue or is it just the way it is?
Thanks

mindsample

10-10-2006, 04:09 PM

'Light Linking Mode' - This is a common parameter on Mental Ray material shaders. Mode 0 means all lights are included in shading the object. Mode 1 means that specifically connected lights are the only ones used. Mode 2 means that specifically connected lights are the only ones NOT used. Mode 0 is the fastest to render.

See also:

http://www.highend3d.com/maya/tutorials/rendering_lighting/shaders/135-3.html

CharlesVarenne

10-10-2006, 05:01 PM

thanks for the answer but i knew that. What I meant is that I put the same setting on 2 different model which are in 2 different .mb file and the light doesnt react the same way. One react properly by putting 0 in the shader fast skin and 2 in the lightmap and the other by putting 2 in the fast ski and 2 in the lightmap. If I follow the logical way. Both of my model should have a light linking at 0 in the fast skin shader and 0 in the lightmap. If i do that both are not reacting properly to the light.

Does any other parametres affects this setting?

CharlesVarenne

10-11-2006, 01:36 AM

Oki I found that in the Maya help
mode is the mode selector for the lights list: all (0), inclusive (1), or exclusive (2). All is faster than inclusive, and inclusive is faster than exclusive.
Which is apparently what mindsample said.

However I have been tweeking around with the lightlinking, the algorithm control and samples of the ligthmap. I have been doing so on a model which didnt react to the light at all even if i put 0 in the lightlinking in the lightmap and the shader. This model only reacted to the light when I put 2. Which is apparently not what it should to be (I checked all my lights and they are all linked properly.)
So with all this tweeking I manage to have the colour of the object but not the sss. I then put different number in the light linking like 3 for example and i get the sss:rolleyes:. So I end up with this conclusion. The light linking is different on each object and nothing is logical in the setting and so you have to test each time how your shader is going to react to the light. If someone have any explanations I will be gratefull. I will keep on my testing and if I find some other solution i will post them here.

CharlesVarenne

10-11-2006, 10:05 AM

Sooo stupid :cry::cry::cry: Apparently it is just a stupid bug. What I found is if you have your model not catching the light anymore and having the settings on 0...then you just have to put an other shader like the lambert1 for example on your model and then reput your sss shader. Then it will work normally... or at least it did in my scene. :eek::eek::eek: I cant believe i have been wasting so much time with this problem especialy when I figure out such a solution :p

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