Newbie - question about expression editor

[pigpen]

Hi. I have a question about the expression editor in Maya 4. I'm going through the bouncing ball tutorial in the "Learning Maya" book, and right now I just made the ball scale in the Y direction to make it elongate by using the scale tool. Now the book is having me add an expression so that the X of the ball with by altered too. I'm trying to alter ballScale node I created with the expression sx = 1/sy in the expression editor. Everytime I hit create, I get an error "Error: Attribute already controlled by an expression,keyframe, or other connection, sx". How can I diagnose whats going on?

Thanks for your patience. I just started taking a maya class yesterday and I'm really really new.

-Andre

[jschleifer]

have you set a keyframe for sx already? if so, then your expression won't work.. maya only allows you to make one incoming connection to an attribute. So if you have a keyframe on scaleX, then you can't make an expression..

In reply to:
Hi. I have a question about the expression editor in Maya 4. I'm going through the bouncing ball tutorial in the "Learning Maya" book, and right now I just made the ball scale in the Y direction to make it elongate by using the scale tool. Now the book is having me add an expression so that the X of the ball with by altered too. I'm trying to alter ballScale node I created with the expression sx = 1/sy in the expression editor. Everytime I hit create, I get an error "Error: Attribute already controlled by an expression,keyframe, or other connection, sx". How can I diagnose whats going on?

Thanks for your patience. I just started taking a maya class yesterday and I'm really really new.

-Andre

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jason schleifer
animator
weta digital

[pigpen]

Weird my reply earlier didn't make it through... Anyway, I have a keyframe already set for sy, but not sx. I used the scale tool to squash the ball along the Y axis and then pressed the "s" key to make a keyframe. Is there a way of seeing a list of keyframes and it's properties?

One thing the tutorial had me do was move all the attributes (except for scale Y) of the ballScale node that I created, to the non-keyable list by using the channel control window. So when I keyframed the ballScale node by scaling the ball in the Y axis, I only keyframe the Y attribute. Because the X attribute is part of the non-keyable list, does this prevent me from making an expression? sx = 1/sy. I'm supposed to maintain the volume of the squash ball as it bounces, by using the aforementioned expression.

Thanks