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MrHoo

Packed Prims - attributes not affecting material with sss

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Hi folks,

hope my problem is not to silly...

I've attached a test scene below.

--

I have an object with an attribute "randCol" altering Cd. I pack the object and then copy it several times on a circle.
So far so good. Giving the object a material with some color has the desired effect, having some spheres showing the color more and others not...

Now turning on SSS gives me the effect only on one random picked object, the others render black.

So how would I get the SSS on all the others? In the mantra node I have "Save all materials and shaders" tuned on. In the shader I use "Use packed color"
Do I have to use some "Render State" magic and if yes, how?

Thanks in advance!

Dominik

packed_rand_sss.hiplc

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Haven't played too much with Principled Shader, but it looks like the SSS is linked to the Base Color (Cd) parameter. The scattering happens on all spheres, but on your "color_by_randCol" Attribute Wrangle node you've clamped the Cd attribute on all but one sphere to be really dark so it's not really visible.

In your setup you can just use the "Use Point Color" option since the Cd attribute is on the points of your unpacked geometry, not on the packed primitives themselves. Mantra will unpack the packed primitives at rendertime and find the Cd attribute.

Edited by berglte

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Thanks for your answer, but if I try your suggestions it does not work, especially because I had already "Use point color" ticked. So if you just fire a render of my test scene, you will notice all rings have one significantly noticeable blue sphere, if you then go in the shader and activate SSS, all rings get black except on ring, with correct SSS showing.

A friend of mine suggested to throw out the "pack" node and use copy stamp instead with "pack and instance" ticked. That should work.

But:

In my bigger setup, I have a blueberry, which has the same attributes. I write it as a bgeo.sc to disk, then having a RBD sim to place them in a bowl and on a table using a lower geo representation and after that i instance the hi geo on the originally used lower ones.

Here I have the same issues with the above mentioned SSS problems... Still have to dig deeper...

Edited by MrHoo

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Hi,

I can't solve it... I uploaded a scene with the original object.

https://we.tl/fL6ZWnfunE

If you render right away it looks fine, because it does not use any packed prims. I f you render out the geo from the rop and then pipe the file node in the copy nodes, you

should see, that only one berry has SSS, the other not.

Maybe somebody can help here...?

Thanks

Dominik

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Hi dominik, I tried rendering your file and It seems to be working the same, whether I render directly or from file :/
I get some light SSS on some of the spheres of each berry 

Edited by ciliath
Precise

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Though the SSS in my scene looks much more noisy and kinda blue, It does appear in both cases and on the same spots as in your example.

Im at work so cant post my result, ill give it another try once im home.

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You are right. With 16.0.633 I get your behaviour...I had a look to the changelog ... Seems that they changed/fixed some things...

thx for pointing !

Edited by MrHoo

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