Editing Expressions

# 1 22-03-2006 , 09:06 AM

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Join Date: Jan 2004

Location: Tempe, Arizona, USA

Posts: 224

To create an expression in MEL, you would do this:

expression -s "ls.rotateY = time;" -o expression1 -ae 1 -uc all ;
// Result: expression1 //

I actually did not code that, I did it in the expression editor and just copied it out of the script editor. . . But it is handy to know how to write the code. If you want to edit an expression after it has already been created, you would do this:

expression -e -s "ls.rotateY = time * 3;" -o expression1 -ae 1 -uc all expression1;
// Result: expression1 //

Note the extra -e in the edit expression code. You also must name the expression which you wish to edit! (expression1).

The usefullness in this coding is very well demonstrated in the Walkerman program as part of the code that controls the ability to toggle the hand control so you can either control all four fingers at once or one finger at a time . . . . user added image

"The Sage as an Astronomer: If you still see the stars as something above you, you lack the eye of knowledge." Friedrich Nietzsche

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# 2 25-03-2006 , 02:01 PM

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Join Date: Oct 2004

Posts: 27

I normally keep all my expressions in one place, eg create a locator and add an attribute to it, say DoNotDelete, and set it in the expression to 1.

ExpLocator.DoNotDelete = 1;

then all the other expressions get stuck under this one. Not to everyones tastes perhaps but when you have a lot going on i find it much quicker to scroll than remember the name or where it was.

AnDy

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# 3 25-03-2006 , 05:36 PM

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Join Date: Jan 2004

Location: Tempe, Arizona, USA

Posts: 224

My trick is searching out the string that builds the expression. It is unique, because Maya will not allow you to create two expressions controlling the same attribute like "ls.rotateY". If I need to change an expression in run time, I just search it out and edit it. If I want to see the expression as it appears, I just copy it to the script editor and print it. This is a key method used in the Walkerman program I created, it allows me to change the gaits and control the hands in runtime.

"The Sage as an Astronomer: If you still see the stars as something above you, you lack the eye of knowledge." Friedrich Nietzsche

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