cman2k's eyeShader

cman2k · May 2010

Sup polycounters!

I've been trying to learn how to write my own shaders, and in the process I decided to work on a 3ds Max shader for the community. I didn't want to make another Do-it-all shader, we seem to have plenty of awesome versions of that, so I decided to do something more specialized.

It's been a great learning experience for me. I hope some people find it useful. Feel free to ask questions, and please post your results!

Features:

Diffuse maps: Separated Cornea and Iris Diffuse and Normal maps with seperate texture coordinates
Normal maps: Separate Cornea and Iris Specular controls
Parallax Offset Mapping (POM): used to simulate Iris Indentation and Cornea Refraction. Hard to 'see' in still image.
Pupil Dilation: Similar in concept to Valve's pupil dilation, this is done entirely through UV math!
Cubemap Reflections: Cubemap-based reflections with Strength, Contrast and Fresnel Falloff controls
Image-based Ambient: Cubemap-based Ambient lighting
Hemispherical Ambient: Hemispherical ambient lighting in UV-space.
Shadow Map: Shadow map used to simulate eyelid-shadowing.
3-Light support!

Possible Future Features:

"bounced" specular for iris interior
Specular "Shape" mask? What if we can mask specular to a shape, to fake a light source?
"negative" fresnel strength support (for flipped fresnel calculation) per Pior's suggestions
"hemisphere shadowing", as an alternative to shadow-mapping. might be more flexible and overall better.
Investigate adding fake chromatic abberation to pupil specular, maybe with a texture?
optional second cubemap for ambient
Tint masking: 3 color mask texture (Iris outer, iris inner, pupil)?
1D tint masking?: what if we just map a black&white iris to a 1D ramp? more color range and control? harder to author?

**DOWNLOAD HERE!**

Malus · May 2010

Very nice.

Any chance of a Maya version?

poopinmymouth · May 2010

Ufff, looks hot! Thanks for this dude.

Eric Chadwick · May 2010

Nice job man!

Ged · May 2010

sweet work thanks for the effort, Id love to try this some time

Michael Knubben · May 2010

Thanks for sharing this! I know it takes extra effort to prepare something for release, so I'm glad you didn't decide to keep this to yourself as an exercise.

StefanH · May 2010

That looks very cool. Very promising. Thx a lot for sharing!

Firebert · May 2010

Nice job man! Thanks a ton for sharing! Keep on writing dude!

BradMyers82 · May 2010

Wow this is great! I have been looking for something like this for a long time. Great work!

cman2k · May 2010

Glad to see this being well received, means a lot coming from you guys. 8)

MattLichy · May 2010

Looks sick. Nice job

kodde · May 2010

Looks cool. Nice to see people posting shaders here.

I also played around a bit with dilation with a shader using a texture instead of UV animation. Was pretty neat, you could do whatever shape of dilation animation you wanted.

youtube.com/watch?v=CN9alIFB-d4

Keep going I wanna see those future updates.

Thanks for the reference

ScoobyDoofus · May 2010

Hey! This looks and works great. Exactly what I needed. I started trying to do something like this with ShaderFX and UDK last night, and here you've already made it happen.

I cant wait for multi-light support as that'll really help put this over the top for me.

cman2k · May 2010

Kodde: that's RAD dude! Is it a multi-frame texture, like actual texture-based animation?

Scooby: I got multi-light support working, but I have some things to clean up. expect an update tomorrow!

kodde · May 2010

It's a gradient texture where you choose to clamp at a certain value. So for instance any value below 0,3 gets black and any value greater than 0,3 gets white. Use that as a mask. Then you can animate where to clamp which can result in some interesting results. I've also integrated the normal map transition to dynamically create that border to make the outer layer seem "thicker".

Like this image:

cman2k · May 2010

MAN kodde, I've used that technique in other shaders but I never would have guessed you could have gotten such a smooth result out of it! Especially with the normals, that is really nice!

pior · May 2010

Very cool!
I think the fresnel falloff would work better the other way around tho. More shiny on the edges of the volume, and less shiny inside...
http://wiki.blender.org/uploads/thumb/c/c6/Manual-Part-III-fresnel-ball.png/300px-Manual-Part-III-fresnel-ball.png

Also on your exemple it looks as if the bump on the veins is flipped maybe...

Hope this helps! Cant wait to play with it.

cman2k · May 2010

Hey Pior! Actually I had the standard fresnel falloff implemented exactly as you suggest, and I purposefully flipped it after looking at a lot of eyeball references. It seems to me like you never want the iris to have no reflection and the outer edges to have a lot.

This is something more common to metals and plastics and stuff, and at first I thought it was maybe just the nature of reflection. Wikipedia seems to support this; http://en.wikipedia.org/wiki/Fresnel_equations

But after looking at a lot of eyeballs it seemed to me like I should shrug that off and just make it look "right". My rationale here was that in general less light probrably hits the sides of the eye because of the surrounding facial structure, so less light is able to be reflected. This is the phenomena I'm trying to simulate here, rather than the standard mathematical fresnel reflection falloff. This is what feels more natural and close to real-life reference to me as well.

Thinking about it some more, it would certainly be possible for me to support both..but I have to question if its necessary and what gains it might have...

If anyone disagrees with me or makes a good argument for it I'd be happy to consider changing it though.

And right you were with the normals! An embarassing mistake, this is what I get for making normal maps at 4 in the morning instead of sleeping...haha!

rahul_shrimali · May 2010

Thanks for this dude

pior · May 2010

Yup, totally agree, it doesnt have to be math-correct to look good, especially since everything on a computer screen is a hack anyways! And youre right too, we mostly see reflections in the middle of the eyeball rather than outside.

Maybe because the 'wetness' of it creates some kind of continuous membrane, getting up near the edges, hence sending the reflections away ?

Who knows hehe.

Supporting both miiiiiight be useful in the case of a standalone eyeball model maybe ...
Or just for added flexibility just in case (who knows what kind of alien stuff could be achieved with this shader!)

Great stuff!

Funky Bunnies · May 2010

oh man, carlos! this is awesome!
eyes are about to look a lot more badass

cman2k · May 2010

latest update;

Light usage is controlled via the technique (you must switch to the 3-light technique in order to use 3 lights!)

also: normal-map fixes, as per pior's suggestion.

**DOWNLOAD**

almighty_gir · Jan 2011

wish i could do this kind of thing in UDK :P

Neox · Jan 2011

what stops you from doing it in udk?

almighty_gir · Jan 2011

the fact that i have a brainfart roughly every 5 minutes that procludes me from doing even the most basic shaders...

hell, even copying the reflectivity shader from the UDN website throws back errors...

cman2k's eyeShader

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