CGTalk - Any help on making this shader? (Picture) Eyeball.

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GuyRamsey

04-11-2006, 07:40 PM

Hey

I'm a complete n00b when it comes to shading in Maya, I recently started an eyeball using Adam Baroody's tutorial, everything is fine except for I cant seem to duplicate one shader, which is the white section of the eye:

http://www.3dluvr.com/rogueldr/tutorials/eye/eyewhite_shader.jpg

I've tried trial and error for a long time but havent succeeded, i've also looked for other tutorials but all i find are tutorials using a transparent layer over the entire sphere, unlike the shader Baroody created, I'm really stuck so any help would be appreciated!!!

Thanks

Guy

Kako

04-11-2006, 09:20 PM

I think this link can help...

http://www.cgrenaissance.com/tutorials/reflections.htm

Kako.

Rens

04-12-2006, 01:16 AM

Actually that tutorial isn't completely correct. If you want true Fresnel reflections then you need to adjust the Ramp. It's not linear.

I've included some images from a shader I made in XSI that uses the actual formulas to calculate the amount reflected. You can see that the bar stays the same colour for a long time and then it ramps up to white.

Take note of the amount reflected when viewed at a 0° incidence angle (the left side of the bar/in the middle of the sphere). For an Index of Refraction (IOR) of 1.5 (~glass) that is about 4%, for an IOR of 2.5 (~diamond) that is around 18%.
The IOR of the eye is around 1.4, that means about 3% reflected at 0° incidence.

Hope this helps. :)

Rens

Rens

04-12-2006, 01:16 AM

And the other two at IOR 2.5.

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