Unfortunately, there are still a bunch of places in maya that only
take MEL (and not python) - expressions being a big culprit.
My general approach when I have to do stick in some mel code into a
python script is to have the mel call a python function, instead of
putting in a mel literal string.
ie, instead of:
Method 1 - Raw String:
=================
melCommand = r'''
$someVal = $someOtherVal
'''
I might do:
Method 2 - Call python function:
=======================
melCommand = r'''python("import myCommand;myCommand.go()")'''
However, expressions are actually their own language, similar but
somewhat different from mel... and I seem to recall that last time I
tried to mix python and expressions, there were some additional
complications... something to do with imports, I think? So, trying to
do Method 2 may end up being more trouble than it's worth, especially
if it's a very simple expression.
If you want to use a mel string, but need to dynamically change it,
you'll have to fall back on string formatting operations, I'm afraid.
Ie:
expressionCommand = r'''
spriteScaleXPP=rand(%f,%f);
spriteScaleYPP=spriteScaleXPP;
spriteSpin=rand(%f);
spriteTwistPP=rand(%f,%f);''' % (scaleMin, scaleMax, spinMax,
twistMin, twistMax)
(Look up Section "3.6.2 String Formatting" in the python help for details.)
Note that, for readability, using the r (for a raw string literal),
and triple quoting it can help a lot (see section "2.4.1 String
Literals" in the python help for details).
Finally, as regards your outlinerEditor problem - maya GUI callback
CAN generally run python code, but there's some weird issues to work
around. For details, see this topic:
http://groups.google.com/group/python_inside_maya/browse_thread/thread/4fe55cd54ebb822/7fffe668f7b814e1?lnk=gst&q=gui+callback#7fffe668f7b814e1
...and look for Ofer Koren's post, which actually quotes the pymel docs.
Good luck!
- Paul
On Tue, Mar 10, 2009 at 9:17 PM, [email protected]
<[email protected]> wrote:
>
>
> Hi Guys,
> this is probably one of those questions that has been asked a
> million times but meh, dynamic expressions as we all know are written
> in maya, as mel expressions, and to use these in python we simply
> write it as MEL in brackets and all is dandy. except how do we edit
> the contents of these expressions? can we even do so ? as they are MEL
> scripts i am unsure. i thought the MEL.EVAL might be of help but am
> unsure.
>
> Example:....
>
> mc.dynExpression('%s'%spriteOutParticleName,s="spriteScaleXPP=rand
> (0.5,1.8);\r\nspriteScaleYPP=spriteScaleXPP;\r\nspriteSpin=rand
> (-90-45);\r\nspriteTwistPP=rand(-90,90);",c=1)
>
> basically how can i edit the values inside the " ", inserting
> variables etc. HELP !
>
>
> so i surrender this to the PYTHON gods, how do we edit MEL dynamic
> expresssions, through python ?
>
> As an offering to the said gods i present the solution to
> another python/Mel problem
>
> if you need the outliner in your GUI, which is quite useful, and need
> a command to be executed whenever the user clicks on an element with
> in the outliner... you can t. it will only execute mel commands. weird
> no? after a few hours of pointlessly playing i ve solved this issue by
> using a mel wrapper. this is just one example but the principle is the
> same
>
> import maya.cmds as cmds
> import maya.mel as mel
>
> def tester():
> print "hello"
>
> mel.eval( " global proc wrapper() { python( \"tester()\" ); } " )
>
> cmds.window()
> cmds.frameLayout( labelVisible=False )
> panel = cmds.outlinerPanel()
> outliner = cmds.outlinerPanel(panel, query=True,outlinerEditor=True)
> cmds.outlinerEditor( outliner, edit=True, sec="wrapper()")
> cmds.showWindow()
>
> just thought i d share it
> >
>
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