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Backfacing polygons in SF

Gadget Girl

Extraordinary
Contributing Artist
So an interesting thing happened. I've made a very simple shader to give a raw silk sort of look. Interestingly the backfiring polygons in Superfly and turning black, and I'm not sure why. When I add an image map, I get a shadowed version of it on the other side, but for some reason without one, I'm getting black.

Here's what I'm talking about:

The lining has become a thick solid black.

Here's a screen shot of the material:

Now I did change the Geometric_Edge_Color to white after I did the render, because it was black and I thought that might have been it, but it didn't make a difference. In Firefly I get what I more or less would expect:


Now to be honest, I would love to be able to do different things with the backfacing polygons. My understanding is that is doable in SF but not really in FF. But even without doing cool fancy things, it would be nice to have it look like the same piece of fabric on both sides.

Any ideas on what is happening?
 

phdubrov

Noteworthy
Contributing Artist
Quiq fix — try tick "Normals forward" on.

About backfacing/two-sided materials in SF — it's doable, I'm working on tutorial/MR combo product now: vegetation, cloth, utility nodegroups.
You need use Cycles nodes for it, Geometry:Backfacing is a key. Plus a bit of vector math.
 

Gadget Girl

Extraordinary
Contributing Artist
Thanks. I figured a true two sided shader was going to be difficult. The Normals forward didn't work, but I did figure it out, even if I don't understand it. I used the Wacro to add SSS to the fabric. That macro seems to change the Diffuse Color in the Simple pane black, even though the Diffuse Color in the Advanced pane stays white. If I change the Diffuse Color in the Simple pane, I can control the color of the backfacing polygons to some degree. For some reason white just gives you a grey, but in this case I changed it to a strong blue and this is what I got:

 

Miss B

Drawing Life 1 Pixel at a Time
CV-BEE
About backfacing/two-sided materials in SF — it's doable, I'm working on tutorial/MR combo product now: vegetation, cloth, utility nodegroups.
You need use Cycles nodes for it, Geometry:Backfacing is a key. Plus a bit of vector math.
I was just reading a thread on the SM Poser forums about this setup, and it works nice with just diffuse colors. However, I'm having a heck of a time plugging in texture maps to the Color nodes of the 2 DiffuseBsdf nodes for the front and backfacing polys, so I'd love seeing a tutorial on it, or are you just planning on including the tutorial with your MR combo product?
 

phdubrov

Noteworthy
Contributing Artist
Tutorial really is main part.
Textures — just use FF image node. No need for additional setup and works with Netherworks MATPanel if you have one.
 

Miss B

Drawing Life 1 Pixel at a Time
CV-BEE
Unless I did it wrong, I tried plugging in a texture in the Diffuse_Color node of the FF palette, but it didn't work, and I'm not sure I want the same texture for both the front facing and back facing polys. I was trying to figure out a way to have a different texture on each side, or at least 2 different colors of the same texture on either side.

I would've thought plugging them into the color nodes of the 2 Diffuse_Bsdf palettes would work, but it doesn't.
 

Miss B

Drawing Life 1 Pixel at a Time
CV-BEE
AHA! See that's what I tried. OK, I guess I'll have to check out your tutorial when it's done. ;)
 

Gadget Girl

Extraordinary
Contributing Artist
Here basic diffuse setup. Just one thing - simple mix ready materials as was said in SM forum not always work. Hence tutorial.
Thanks for this! I tried it out and it worked. Of course now that I know how to do this, I'm going to make Firefly and Superfly versions of my materials. It actually means I can do something I wanted that I thought I couldn't do, which is to have the inside of my brocade fabric have a sort of inverted color set the way real fabric does.
 

Gadget Girl

Extraordinary
Contributing Artist
And now I've found a new problem, or at least an annoyance. So here's my render with the two sided material in Superfly.

This is just a quick render, but the materials look the way I want. Here's the thing. Now when I'm posing the figure, the materials look like this:


I've tried simplifying the Preview material down to just an image map, and even just a solid color, but this is all I get. Is this some sort of bug in Poser, or once you've set up a more complex cycles node are you just not allowed to preview anything that looks even remotely like your texture?
 

phdubrov

Noteworthy
Contributing Artist
It's complicated. Basicly yes, if you add Cycles shaders.
But! If you ready to work with PoserSurfaceRoot in Superfly (which sometimes gives you (me) unpredictable), you can use such construction:

2-sidedPS.png
 
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Miss B

Drawing Life 1 Pixel at a Time
CV-BEE
Well, as I posted on the Poser forums, I did get it to work after all. I had totally forgotten to UV map the prop I had created, so once that was done, it worked like a charm.


BackfacingPolysTest-Success.jpg
 
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