Constrain a texture map to a Locator

[brcummi]

I am a student, new to Maya, and recently tasked to help with the rigging of a model for one of our class animation projects. The eyes of the model are not spherical (it is more oblong, similar to an egg) so we can't just constrain the sphere to aim at a locator. I am looking for a better way to do this.

One way that i thought of was "slipping" the texture map around the object, keeping the geometry static, while simulating the movement of the pupil, etc...

Is this possible? Do I have other options?

thanks,
Brian

[empleh]

What's up Brian. You could try creating a projection for the eye texture. Then position the texture in a neutral strait forward position so that the eyes look the way that you want. Then move the pivot point of the projection to the center of the sphere(eye). Now constrain the projection to a locator.

This might work. Since the slope of the eye surface is not constant there might be some weird effects though. Who knows.

Good luck,
ww

[perseus2]

In the "learning Maya" book, there's a tutorial called "Salty the Seal". In that tutorial, there's a good method of doing what you want it to do - you can deform the eyeballs with a lattice. Rotating the eyeballs directly or via an aim constraint will keep the deformation constant as the eyes roll.

You can also do this with grouping - if you group a sphere to itself and squash or scale the top node, the lower node will rotate within the context of that squash.

[gmask]

What you can do is to make a normal sphere and constraint it. Then make the sphere oval with a lattice. That way the eye will rotate properly and follow the aim contraint while maintaining the proportions of an oval. A tutorial of this is in the Salty Chapter in the Learning Maya book.

[empleh]

"you can deform the eyeballs with a lattice. Rotating the eyeballs directly or via an aim constraint will keep the deformation constant as the eyes roll.

You can also do this with grouping - if you group a sphere to itself and squash or scale the top node, the lower node will rotate within the context of that squash. "

Nice.

I wondered about doing it this way but was too lazy to try. Tsk, tsk.

ww

[brcummi]

hey guys,
thanks, everyone, for your help...i am using the method of grouping the sphere to itself. seemed the most straightforward...and i couldnt get the lattice thing to look quite right. what might i be doing wrong with that, just for the record and for the advancement of my maya knowledge?

Thanks again!!
Brian

[mantrid]

Well actually, there is a much cleaner and more methodical appraoch to this, and it even gives you control of the eyelid also.

Firstly, create a an eyeball. Then duplicate it, and enlarge it. Now you can chop up the larger one, that forms the eyelid and even extrud it or whatever to give it some depth. Now, both spheres should still have the same pivot point (centred). ...

Next, creata a locator, snap it the centre of the eye, NOT constrain. Enlarge the locator so that it is bigger than the eye...i.e. it is easy to select.

Now setup the aim constraint before you apply a lattice...create a locator, select the locator, then the eyeball, constraints>aim. If it doesn't just work when it is applied...i.e. the eyeball turns round and the area of the pupil is not aiming at the constraint, all you need to do is apply a -1 or a 1 figure to one of the aim constraint's 3 axis in the option box when you make the constraint...i.e. it is reorienting the eye to aim correctly by correcting the 90 degree offset of the object's normal.

Next, group the eyeball and the eyelid together and very important...CENTRE the pivot. Now you can apply your lattice. Modify your lattice to shape the eye as you please, then take both lattice nodes and parent them to the eye-Locator. Now, wherever the locator goes, the eye lattice goes, likwise, you need to parent the eye geometry Group node to the locator also.

...now, as a result of parenting to the locator and matching all the pivots centrally, you can freely move the locator (whole eye) and the eye and lattice move together and rotate together. Your Aim constraint should be working, if not, you did not apply the correct setting to one axis in the aim constraint options. Heres the fun part....as a result of applying your lattice to the group node, anything within that group now has a local axis assigned to every vertex in theory, within the lattice. In other words, everything is relative. So, you can rotate the eyelid and it will remain consistant with the shape of the eyeball, and you can move your aim constraint to rotate the eyeball itself, again maintaing the correct shape. There you go. Any questions, I suggest you try to work out the answers yourself first....there would be no fun if I told you everything now would there.