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# 1 19-04-2005 , 11:49 AM
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aim constrain an eye without rotating

Hi all,

I'm trying out some eye-things for my contest-character, but can't get it the way i like.
I want an oval shaped pupil in the center of the eyeball going up/down/left/right using an aim constrain to look at a locator. But I don't want the pupil to rotate. It's kinda like a cartoon eye (I think the eyes of Copperbottom in the movie Robots are similar).

I parented a pupil into 2 joints of which the root has the aim constrain. I can use Set Driven Key to scale the bone when the root is rotates by the aim constrain, so the pupil wont roll back into the eye. But I don't know how to keep the pupil from rotating.
Is there another way doing this?

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# 2 19-04-2005 , 04:56 PM
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If you added a null or a locater that was outside of your current heirarchy, you could use it to set an orient constraint on the pupil itself so that while the pupil will translate when your root pivots, it will keep the orientation of the null object.

Was that clear?

# 3 19-04-2005 , 05:01 PM
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# 4 22-04-2005 , 02:32 PM
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Sorry for the late response. It's been hell busy at work. Pffff.

I think I've been through almost all of the Maya "eye" tutorials on the net. hehehe. But haven't found any yet that cover this. The "Cartoon Eyes" tutorial by Brian Immel is about controlling the look_at using aim constrain. But I want to control the look_how user added image of the eye. Controlling how the pupils behave while looking at the target.

The orient constrain worked like a charm. And easy to set up. user added image Thanks.

I limited the rotations of the joints so the pupil doesn't move off the eyeball area going up/down or left/right. However this will create a rectangular perimeter for the pupil to move in and not a circular. So the pupil will move off the eyeball looking far in the corners of the eye (see 1 in the animation). Any ideas on how to fix this? Must be some complicated mathematical expression for this.

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# 5 22-04-2005 , 02:36 PM
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For those interested who stumble onto this thread with the same question, here is the .ma file.

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File Type: ma eye.ma (74.6 KB, 309 views)

Last edited by Eelco; 22-04-2005 at 02:50 PM.
# 6 22-04-2005 , 02:40 PM
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ive never approached modelling the pupil out of geometry, what i do is get a rough shape of the eye and then use a texture map to add the detail.

I then parent the object to the locator and animate that (poles facing the camera).

because if you think about it the human eye is not made up of several external pieces but one complete object (with bits and bobs on the inside) and if when you move your eyes the eyeball rotates to that angle slightly.


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