Post render frame MEL

[ruchit]

Hello,ppl tell me how to use this option..i have MEL script(28 lines long).Where i have to execute this first ?? in script editor or expression editor?? & then wht i have to put in post render frame MEL to run that ??
if you know any good tutorial on how to use this "post render frame MEL" then it will save my time.
Reply ASAP.Thank you

[ruchit]

for testing purpose,In script editor i type this
int $a=15;
int $b=10;
int $c=$a+$b;

And in post render frame MEL i type this
print $c;

But after render complete i got error in mayaRenderLog
 Error: print $c;
Error: "$c" is an undeclared variable.

so tell me which silly mistake is i m doing.

[thnkr]

First define a procedure in a mel script that is in the proper location; one of the directories in the script path. You can find out what that is with 

getenv MAYA_SCRIPT_PATH;

give that script the name of the procedure. In this example, use the file name myAddition.mel

global proc float myAddition(float $a, float $b){

float $c;

$c = $a + $b;

return $c;

} 

Now add this line to the render settings Post render MEL:

 print myAddition 5 6;

If you're just trying this and you don't care about loosing the procedure after quitting Maya, you can just run the procedure declaration in the Script Editor, but if you want to use post render MEL commands in a batch render, you must do it the way I just showed you.

[joojaa]

Where i have to execute this first ??

If its in mayas lookup path maya will find it. If not then you should put it into yoru lookup path. So the aswer is you do not need to execute it first.

so tell me which silly mistake is i m doing.

scoping. while it MAY be true thet tha $a, $b and $c may under some circumstanes be scoped as global that is not teh case once you go to batch render, so you must understand what maya keeps and what not easiepcally if you intend for stuff to live between sessions.

[ruchit]

@Michiel Duvekot & Joojaa
thnx very very much
Friends i m doing rendertime compositing with one MEL script but i m gettin this error
Error:     string $imgFolder = "C:\Documents and Settings\ruchitb\My Documents\maya\projects\default\images\";
Error: Unterminated string.

Wht's wrong in my code

[joojaa]

strings escape on backslash ("\") so ir you want to type:

C:\Documents and Settings\ruchitb\My Documents\maya\projects\default\images\

as a queted string literar you must double the backslashes ala:

string $imgFolder = "C:\Documents and Settings\ruchitb\My Documents\maya\projects\default\images\";