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Tutorial: Sperm shader.
12-24-2013, 07:12 AM (This post was last modified: 12-26-2013 12:11 AM by uchuujinx.)
Post: #1
Tutorial: Sperm shader.
About a year ago I tried to make a shader for sperm props which could be used on any of the different products available online for Poser. But I couldn't get anything decent to work back then, but now I've had the chance to get back to it and figure it out.

This is SIMPLE shader which is a basic template for any liquids and fluids you may want to produce on Poser. This shader is 99.9% physically accurate: it is procedural which means you don't need any bitmaps to use it, and you can use it with ANY object, which I'll show using three different props...

[Image: attachment.php?aid=1926]

If you're familiar with Poser's advanced material room, I imagine this shader won't be hard to understand just by looking at it. They're just 8 nodes but that's enough.

It is far from "perfect" because I actually removed any additional refraction. But it is accurate. We don't really need refraction here and it would make the render times slower without any significant improvement.

For the tutorial here I'll be using different props:

Strideribellum's Splooge & Darkseal's Loadz, from Renderotica.
Flinks Water FX, from Renderosity.

The props were scaled, set in place and then parented.

I didn't pay much attention to placing them, because it is a shader tutorial. Though I did some smoothing and pulling here and there with the Morphing Tool, and left the props intersecting the skin for the 'sticky' effect. It could have been done better, this was done a bit rushed.

The props have:
Smooth polygons ON
Cast shadows ON
Visible in Raytracing ON
Light emitter OFF This saves us time through the IDL render calculation.

BTW, this is Leona, she'll be our assistant and she's gladly agreed to get her face creamed for the love of art and science. ~<3

[Image: attachment.php?aid=1931]

Let's move on to the parts of the shader:

[Image: attachment.php?aid=1927]

Reflection_Lite_Mult, Reflection_KD_Mult, Traslucence and Ambient must be set to zero ALWAYS.
Ambient you can use only if you're making an object emitting light for a special effect. A diffuse light emitter, a sci-fi or magical weapon, or those Tron-based things people were rendering when the sequel movie came out.

1. Default Diffuse and Specular in Poser are OK... if you're living ten years ago. They are based on simpler calculation which we don't really use much anymore. That's why we're keeping them unplugged, set to zero, and instead we will use the Alternate channels.

2. I've cheated a little bit here in the way I've used the edge_blend to bring some noise and trasparency shifts in the shader. You could use just the edge_blend and get away with it, but the additional turbulence fakes the impression of viscosity.
This transparency setup is what saves us from actually having to use Refraction at all, which means faster rendering.

3. A Bagginsbill little trick. If you haven't read Bagginsbill's many tutorials about shaders, you should read 'em. The man is brilliant and you'll learn lots from his tutorials.

4. At the end, I didn't need to forward the normals. Now that I think of it, it may have made sense if the props were single sided. The Splooge props have two materials zones, one for each side, which imho it's pointless.

[Image: attachment.php?aid=1928]

5. Glossy is a quick fix for shiny stuff. You'll use Glossy with liquids, metals and of course latex and fetish stuff.
The Blinn node would have been also an appropiate alternative, More often than not, it's a matter of personal choice.

6. The Fresnel effect if the whole key behind getting good results with Poser. I even use it to drive specularity in transmapped hair shaders.
Glass, water, plastics, almost everything depends on this Fresnel effect.

If you ever want to render a girl wearing eyeglasses, and getting her face gooed, while she squirts, you'll thank Fresnel for being such a nerd.

[Image: attachment.php?aid=1929]
Almost there.

There's a typo up there. Clear water is 1,33 not 1,44.

7. Speaking of this Fresnel effect, there are lists online with values for different materials you might want to reproduce. Sometimes you'll want the exact value but other times an approximation is enough. Experience will tell you when to do one thing or another and you might find yourself guessing the refractive indexes of stuff correctly.

I used 1,44 to separate the SSS from its reflection, but 1,34 or 1,54 would've been OK too. The higher the number, the brighter our reflections will be.

8. No comment, the Reflection node is very intuitive. If you want to save even more time, set Softness to zero. We don't need a lot of Quality either.

[Image: attachment.php?aid=1930]

9. We've Subsurface Scattering (SSS) here. It is what will give us the real translucence. We've gone through transparency already by faking refraction and we've added our reflections so this is all that is left.
Changing SSS parameters gives you all the options you need in this case.

I used 0,05 in the scale, but as the props all came from different sources, sometimes the scale has to be fixed to match the XYZ scale of the prop.
Varying SSS scales across the props it's also an option (0,025 up to 0,1) if for any reason you want different qualities in your scene, i.e. group sex with different guys bukkaking the same girl.
Using different colors or even textures can also bring some interesting effects. It's worth trying.

I forgot to mention, I set the Scatter_Group to 5 because I prefer to keep them separated. It is not really important if you put all your SSS in the same group.

And that's the end of the tutorial. Let's see how it all came together... on Leona's face:

[Image: attachment.php?aid=1932]

She seems happy, despite mess.

Overall the results are not bad. The problem itself are the props and Poser's apparent limits on physic simulations, which hardly match the behaviour the shader is trying to accomplish. For example I had to cheat a bit using the Morph tool to push and pull some of the props, and change their size. The Loadz props around her mouth and chin look pretty nice.
I'm also fond on how the WaterFX seems to drip from her cheek even if it's a bit overdone and the particles look too big.

If anything, this example is a bit on the watery, transparent side of what this shader can accomplish. But now you know what to change and how to do it, and I hope anyone can get better results than my rather rushed render.

I'm wondering now what would happens if these props were used in a cloth simulation... but that's another problem for another day.

And that's my christmas present for you guys, have happy holidays and a merry porn-rendering!

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12-25-2013, 11:33 PM (This post was last modified: 12-25-2013 11:34 PM by uchuujinx.)
Post: #2
RE: Tutorial: Sperm shader.
This one shader is interesting too. It gets an interesting translucence from blending refraction with SSS, intead of cheating with Edge_Blend in Transparency values.

Although renders times increase a bit, the result is interesting, though it looks a bit too pearly... not bad for another shader sone in a rush LOL

[Image: attachment.php?aid=1935]
[Image: attachment.php?aid=1936]

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12-26-2013, 12:57 PM
Post: #3
RE: Tutorial: Sperm shader.
Thank you very much for taking the time to create this informative tutorial. Your results are excellent Big Grin

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