Rotating an eyeball

[killingtool]

In the tutorial at:

http://canimation.com/tutorT002.html

The author creates an eyeball by building a sphere then rotating it on the x axis 90 degrees. This places the north pole of the sphere directly where the pupil would be.

Now I'm trying to figure out how to place the texture on the eyeball sphere. Seems like the 'Place2dTexture' would give me the ability to rotate the texture around the pole, but there is a "seam" there...and my texture just gets squished as I move my pupil towards the pole.

The author even states in his tutorial:

"ask yourself...Why should I rotate the sphere 90 degree in the first place?"

But unfortunately, he never answers his own question. So I'm asking it here. Why rotate the eye sphere 90 degrees...AND...now that I have, how can I place the pupil texture so that it overlaps the pole?

[stevesayer]

Use a V Ramp texture, not an image file, to create your iris/pupil. Works beautifully. You want the eyeball facing this way specifically so that you can do this, first of all (allows you to control incresing pinkness of colour and veining procedurally along that same V coordinate)... and also because if you want to add more geometrical detail (specifically the bulge of the cornea) it fits properly with the existing geometry.

Anyone have any other answes? --I don't consider mine complete or definitive...

-Steve

[killingtool]

Thanks for your response. Hmmm, did you mean to say U Ramp texture? That did seem to work, but seems to add more complexity. I'm no expert shader, so building an eye shader wont be easy.

I found an excellent tutorial at:

http://www.3dluvr.com/rogueldr/tutorials/eye/eyes.html

And think I may trying building the eyes in this snowman like stack of NURB's, grouping them, and then aiming the group at my aim-constraint target.

Does this sound like a normal/usable way to animate eyes?

The original tutorial I was studying used a cool lattice trick that allows you to rotate non-spherical eyes, so that they do NOT bugle out when you rotate them. I'd like to use my snowman-stack eye groups, but my eyes need to be NON-Spherical. So I hope this lattice trick works on groups as well as solo NURBS.

[killingtool]

I just made a quick and dirty attempt at my stacked eye with aim constaint. If you are curious to see it in action I placed it on my website at:

http://www.zaske.com/files/eyethatworks.mb

Does this seem like a workable/usable way to animate an non-spherical eyeball?

I guess I could then texture the cornea/pupil with seperate texture files or shaders. Not as easy as a sphere with a TIF texture map, but probably more expressive.

I'm still curious how I can lay a texture over the NURB spheres seam or "north pole" or whatever it is called.

[stevesayer]

I may have mixed up U and V. Whichever ramp turns into a nice eyeball texture, that's the one you want.

That is a wonderful tutorial you found; one of the best I've seen for eyes. The procedurals do add complexity but I think the flexibility and ease of control you get makes it worth it.

The whole thing about rotating the sphere 90 degrees has to do with the fact that the tissue of the eye all flows in that direction. Any subtlties you add to the eye (like veins or texure in the iris) will behave better when the poles of the sphere are located at the center of the iris and the back of the eyeball. Otherwise you'd have textures warping around the poles, and that would be visible if your character rotated its eyes an extreme amount. (For example, if it looked downwith eyelids wide open, the pole at the top of the eye would be visible, and the veins wouldn't look right.)

Finally, remember that the center of the pupil is completely black/transparent, so if you put a pole there it will be completely hidden--which is always good.

Hope it all makes some sense now.

-Steve

P.S. Unfortunately I can't view your scene (different versions of Maya), but your setup sounds like it should work fine.