Ordinary Event Message

[dauzer]

Hello all,

I'm new to the community and I have a problem setting something up with my undo plugin as follows:

I try to keep track of the undo queue in Maya, like I'd like to get a message anytime the user is doing something with the scene like adding a new object, e.g., adding a polycube. The only way to catch event like this I found is using the 'UndoAvailable' Event available in MConditionMessage. The problem now is that it is only triggered when the undo queue was empty and has received one new entry. It's not triggered when an entry is added to a non-empty undo queue. So, basically one can work around this problem, if you flush the undo queue anytime you get a new entry and sort of implement your own undo behavior. The problem now is that I also need to catch anytime the user hits the undo button then. But, if I flush the undo queue, Maya is not sending out the corresponding message either (which is 'Undo' in MEventMessage). So, I'm sort of stuck.

I was trying to find another way of catching regular event, like when the user does something and one entry is added to the undo queue, but I couldn't find any appropriate message.

Does anybody have a hint, how to solve this? Any help is highly appreciated.

Many thanks in advance

D.

[joojaa]

read documentation for mel scriptJob, it lists all possible events now you could use SelectionChanged or DagObjectCreated they might be more approapriate for you. (selection changed is basically the get all user events event)

There is however a different approach, you can sugercoat the commands users use to do the objects witha call to your handlers. This has a few benefits, you can ignore scripts, this may also be a downside And you get finer ganular control.

Example:

CODE
//paste into script editor and execute
//don't worry it will get cleared on restart
//if you want it persistent t you need to set it into userSetup
global proc thisIsAExampleHook(string $str){
  print ("i am hooked to: "+$str+"\n");
}

for ($i in menu -q -itemArray MayaWindow|mainCreateMenu){
  if (menu -q -ex $i){
    for ($j in menu -q -itemArray $i){
      //avoid the 2 last of poly and nurbs
      if (!menuItem -q -d $j){
        menuItem -e -c ("thisIsAExampleHook(\""+
        menuItem -q -label $j+"\");"+menuItem -q -c $j) $j;
      }else{
         break; //a bit tacky but works
      }
    }
  }
  else{
     //lets only wrap the fisrt submenus
     break;
  }
}

PS: Don't thank in advance, it creates a iffy aura.

[dauzer]

Hi, many thanks for your reply, it helped alot.

Since, I'm only need one item (undo), I did the following:

OpenMaya.MGlobal.executeCommand("menuItem -e -c (\"python (\\"thisIsAExampleHook()\\");\"+menuItem -q -c undoItem) undoItem")

and it works fine up to the point that he is trying to call the function "thisIsAExampleHook()" whenever I hit the undo button.
So you might also see my next problem... I'm using python to write my plugin.
The problem now is that he is not finding the function "thisIsAExampleHook()", though, it is defined in the python script right in front of the OpenMaya command...

def thisIsAExampleHook3():
print 'hook'

I guess, it's not possible for MEL to recognize that the whole thing is operated from a python script. And I didn't find any way to make the proper call.

Does anybody faced this before, like calling the right python procedure from MEL? In the case there is no possibility to do that, I know that I have to rewrite the plugin using exclusively MEL.

cheers

D.

[joojaa]

Question is why you want to do this. If you implement something that needs to undo you already have undo sections for commands you do. (and theres no possibility for you to attack stuff that isnt yours really)

There may be a more natural way thatn whet your trying to do.

QUOTE
I guess, it's not possible for MEL to recognize that the whole thing is operated from a python script. And I didn't find any way to make the proper call.

They dont run in same space no. you can wrap the call to the python command tough. But thetare not 1 to 1 interchangeable

[joojaa]

Question is why you want to do this. If you implement something that needs to undo you already have undo sections for commands you do, theres a trick to this tough since maya does not store python objects for commands but its own object structure so you need to store them away first, read the docs itts described. (and theres no real possibility for you to attack stuff that isnt yours really)

There may be a more natural way thatn whet your trying to do.

QUOTE
I guess, it's not possible for MEL to recognize that the whole thing is operated from a python script. And I didn't find any way to make the proper call.

They dont run in same space no.

[dauzer]

Hi,

yea right, my application might be a little bit silly, anyway I'm just playing around. But how about this one:

One has a python plugin that does some algorithmic stuff... let's say setting up some data structures for later rendering, whatever. Then you initialize the plugin and setup your variables and connect to the right event handlers to collect your data etc.. The you want to trigger the whole thing by adding a new maya menu item, meaning that you have to call the right function in your python script using the '-c' option in the MEL menuItem command, which is not possible as far as I understand.

This problem seems pretty much standard to me, but as far as I understand, there is no way to make it work, since you cannot call the right python function in your script and have access to your data structures that were already generated. The weird thing though is that Maya supports Python on purpose and since you can use both MEL and Python in the script editor, it apparently suggests to the programmer that you can use whatever you want... MEL or Python. Though, if you need menu funcionality like I do, you are limited using python.

So, from my point of view, the best solution would be to implement the whole thing in MEL.

best

D.

[joojaa]

QUOTE(dauzer @ 04/17/08, 08:38 PM) [snapback]284335[/snapback]
This problem seems pretty much standard to me, but as far as I understand, there is no way to make it work, since you cannot call the right python function in your script and have access to your data structures that were already generated.

Huh? Ofcourse you can! You just need to make sure things dont get cleaned away because theres no longer no apparent use. (after a script is run its cleaned away)

Easiest is to declare the data global. This has nothing to do with how maya works but rather how PYTHON works. in fact theres nothing maya specific about the python. Ist still not inside maya it just has a api so it runs on side of maya.

But just out of curiosity are you integrating python API calls trough the plugin mechanism or trough the on line interpreter? If not the plugin mechanism then you should be switched to a different sub forum.
QUOTE
it apparently suggests to the programmer that you can use whatever you want... MEL or Python. Though, if you need menu funcionality like I do, you are limited using python.

Well mel and python.cmds are equal things theyimplement same functionality.

But dont mix this with API development its a different thing altogether. API implements commands and nodes, cmds interface implements user scriptability.

And in maya programming if you start your first project with callbacks you have misunderstood mays purpose.

---

Now then a few questions:

• do you want to implement a node?
• do you want to implement a command?
• do you want to implement a exporter?
• do you want to implement a renderer connection?
• do you want to implement a renderer OpenGL?
• do you want to implement a context?
• or are you scripting? (all other gui stuff fall under this ambrella)

QUOTE
So, from my point of view, the best solution would be to implement the whole thing in MEL. smile.gif

Im not the person who insisted thet python made things easier to understand.

Python is NOT easy, its 20 times harder to undertsand than mel on bad day. Its just astonishingly good to hide the fact.

[dauzer]

Hi,

now I'm kind of lost. Ok, here is the deal. I'm trying to write a Maya plugin that keeps track of what a user does. Actually, I want to transmit the user actions to another user so that he can see with the first guy is doing in Maya. I also want to catch undo events... like when the user is hitting undo.
Later, I want to extend it to all different kinds of user actions, not only undo. this was just the button I started with.
This all is supposed to be set in python.

Here is a skeleton of my code:

CODE
import maya.cmds as cmds
import maya.mel as mel
import maya.OpenMaya as OpenMaya

globalDataStuff=None

def undoTriggered():
    print 'undo triggered'
    # do something with globalDataStuff
    globalDataStuff=2

def initializePlugin(mobject):
    # connect event handlers and do some init stuff
    # initialize globalDataStuff
    globalDataStuff=1
    # connect the undo button
    OpenMaya.MGlobal.executeCommand("menuItem -e -c \
          (\"python (\\"undoTriggered()\\");\"+menuItem -q -c undoItem) undoItem")

def uninitializePlugin(mobject):
    # do all the clean up stuff
    globalDataStuff=None

The globalDataStuff here stands for a whole bunch of data that has to be accessed and transmitted to the receiver.
Well, in this way it won't work, because the python command in MGlobal.executeCommand is triggering a completely new script without giving me the permission to access my data. In any case, he is not calling undoTriggered() at all, because he doesn't realize that this whole thinng is connected to a python plugin.

Do I miss something, or is it not possible to do such a thing in general?
The code above should be loadable as maya plugin by copying it as .py file in the pplugin-directory. It's properly loaded, but anytime I hit undo, he says like:
# Error: name 'undoTriggered' is not defined

best

D.

[joojaa]

QUOTE(dauzer @ 04/18/08, 11:03 PM) [snapback]284407[/snapback]
now I'm kind of lost. Ok, here is the deal. I'm trying to write a Maya plugin that keeps track of what a user does. Actually,

Then your not supposed to use maya.cmds as your base (also your supposed to avoid using maya.cmds inside plug in specific code). Your supposed to make class thet extends OpenMayaMPx.MPxCommand or a node etc if your making a plugin. Whet you have is a script. Different thing all together.
QUOTE
The code above should be loadable as maya plugin by copying it as .py file in the pplugin-directory. It's properly loaded, but anytime I hit undo, he says like:
# Error: name 'undoTriggered' is not defined

Its because you dont implement the minimum requirement for a plug. This IS not scripting the plugin mechanism does not project your functions to the scripting engine. They are separate things. This one is a independent code running on api interfaces as a dll would.

QUOTE
Do I miss something, or is it not possible to do such a thing in general?

Read above. But yest this is quite trivial to do as a naive implementation just open a command port on target machine and pipe the script editor output to the command port.

This can be accomplished with one line of mel on both ends and any deecent ssh application and a pipe for example.

[dauzer]

QUOTE(Joojaa @ 04/19/08, 10:24 AM) [snapback]284436[/snapback]
Then your not supposed to use maya.cmds as your base (also your supposed to avoid using maya.cmds inside plug in specific code). Your supposed to make class thet extends OpenMayaMPx.MPxCommand or a node etc if your making a plugin. Whet you have is a script. Different thing all together.
Its because you dont implement the minimum requirement for a plug. This IS not scripting the plugin mechanism does not project your functions to the scripting engine. They are separate things. This one is a independent code running on api interfaces as a dll would.
Read above. But yest this is quite trivial to do as a naive implementation just open a command port on target machine and pipe the script editor output to the command port.

This can be accomplished with one line of mel on both ends and any deecent ssh application and a pipe for example.

What I have here is no plugin? But I can load it using the plugin manager and it seems to run, since he is responding to the menu click.

Yea ok, so I guess the best thing to do for me is to open a command port to the same machine, since I need to do some pre- or postprocessing before I'm sending out the stuff.

Thanks

D.

[joojaa]

QUOTE(dauzer @ 04/21/08, 11:35 PM) [snapback]284502[/snapback]
What I have here is no plugin? But I can load it using the plugin manager and it seems to run, since he is responding to the menu click.

Yes its a start of a plugin but it does not implement a minimum plugin it just implements the start sequence of a plugin. It has no body to recall, once its strated it has nothing else (that is to say you could do plugin like this but as you say you couldn't do anything smart with it). You have no magical freedom to do whatever you want, you must use the maya interfaces for communication. That is usally called a api.

It also does not implement a script it implements a plugin different thing differet thinking. (, but you can expose it as a command and then you can call it equally trough mel and python)

Now the thing is you should be making a class that then can be evoked.

Take a look at the simplest of simple example in devkit/plug-ins/scripted for arguments sake lets take whatIs Cmd wich implements the minimum requirement for a plugin command.

class scriptedCommand(OpenMayaMPx.MPxCommand):

Contains the interface:

def initializePlugin(mobject) binds it to the code. It runs ONCE you cannot come back to anything other in the cde because you dont tell maya your going to do so.

DONT MIX THEESE 2 THINGS UP, script interface and pai interface. Different thing different use.

[dauzer]

Hi Joojaa,

thanks for the useful hint. I found the following pages related to scripted commands etc.
http://www.kxcad.net/autodesk/maya/Maya\_Do...Python\_API.html

So, I finally derived this solution, which works nicely and does exactly what I wanted... I'm posting the code, just in case someone might be interested in it too.

Thanks alot for your help, highly appreciated!

best

D.

CODE
import maya.OpenMaya as OpenMaya
import maya.OpenMayaMPx as OpenMayaMPx

myData = 0

class UndoCommand(OpenMayaMPx.MPxCommand):
    commandString='MyNewUndo'

    def __init__(self):
        OpenMayaMPx.MPxCommand.__init__(self)

    def doIt(self,argList):
        global myData
        myData=myData+1
        print myData, "YAY!"

def undoCommandCreator():
    return OpenMayaMPx.asMPxPtr(UndoCommand())

def initializePlugin(mobject):
    mplugin=OpenMayaMPx.MFnPlugin(mobject)
    try:
        mplugin.registerCommand(UndoCommand.commandString,undoCommandCreator)
    except:
        sys.stderr.write('Failed to register command')
        raise

    OpenMaya.MGlobal.executeCommand("menuItem -e -c (\"MyNewUndo;\"+menuItem -q -c undoItem) undoItem")

def uninitializePlugin(mobject):
    mplugin=OpenMayaMPx.MFnPlugin(mobject)
    try:
        mplugin.deregisterCommand(UndoCommand.commandString)
    except:
        sys.stderr.write('Failed to deregister command!')
        raise
    # todo for uninitialize: disconnect MyNewUndo from the undo menu item