Maya Crashes When I Reload Plugin?

[daviddoria]

I have a MEL GUI that I use to set some parameters and then call my plugin. Everything works smoothly - I can run the command, change parameters, run it again, etc indefinitely.

However, if I unload the plugin so I can change something in the plugin (recompile and put into the user defined plugins directory), then reload the plugin, then try to run the command from the GUI, Maya crashes! Seems very weird to me - any reason why it would do this?

Thanks,

Dave

[rob-bateman]

normally because you've forgotten to un-register something....

[daviddoria]

what do you mean "unregister"? In the MEL or in the c++?

in the c++ i have:

MStatus uninitializePlugin(MObject obj)
{
MStatus status;
MFnPlugin plugin(obj);
plugin.deregisterCommand("MyPlugin");
return status;
}

but I think that is working fine because i can check and uncheck the plugin as much as I want and nothing complains. I guess it's in the MEL then, but I never "registered" anything, so I dont know what to unregister!

-Dave

[rob-bateman]

hmm. not sure then. 99.999% of the time, it is the uninitialisePlugin() not unregistering as much as it should be. It might be undo information for your command (shouldn't be really), or simply because the mel script was interpretted against the old plug-in and has not been re-run (and is then hitting a now invalid mel command memory location). In theory it shouldn't be that either. You can always try the MFnPlugin::registerGui() method to see if re-running the script everytime it loads the plug-in does the trick.

[daviddoria]

that would actually be very helpful to have the GUI open/close when the plugin is loaded/unloaded. did you mean
MFnPlugin::registerUI() (as opposed to registerGUI)? I have a .mel file that starts with:

window -title "MyGUI";
rowLayout -numberOfColumns 2 -width 100 MainRow;
blah blah

So how do I set "c:/stuff/mygui.mel" to be the registered gui?

-Dave

[korchkidu]

Hi,

check that your mel script doesn't source another script. If this is the case, force the script to be "resourced" by enclosing the source statement into an eval command.

Hope this helps.
K.

[rob-bateman]

CODE
// myGuiCreate.mel
global proc myGuiCreate()
{
}

// myGuiDelete.mel
global proc myGuiDelete()
{
}

// in initialisePlugin
MFnPlugin::registerUI("myGuiCreate","myGuiDelete");

manually sourcing mel scripts for GUI (or using eval) is not recommended since there are occasions when you run maya without the GUI (i.e. rendering). In order to allow renders to work, don't call GUI funcs that will cause maya to error out .

[daviddoria]

so where do i have to put the .mel file so it knows which file to register with those commands? or equivalently, how do you run a mel script from the maya command prompt? I tried simply typing the file name (ie "c:/stuff/script.mel" but that didn't work, so I assumed something like

CODE
// myGuiCreate.mel
global proc myGuiCreate()
{
}

// in initialisePlugin
MFnPlugin::registerUI("c:/sutff/myGuiCreatemel","myGuiDelete");

wont work either. Also I dont have a script that deletes the gui... what does it need to do? simply close the window?

Thanks - you guys always save the day (/week haha)

Dave

[korchkidu]

Hi,

you have to put both scripts (myGuiCreate and MyGuiDelete) in a directory accessible by maya. It will automatically search for scripts named myGuiCreate and MyGuiDelete in those directories and execute them.

@Rob: what if, when building the GUI, you need to source additional mel files first? How do you do this without using the source statement ?

For example, you need, when you load the plugin, to first source mel files and then create the GUI. If you do this, without using the eval command, unloading then reloading the plugin will crash Maya as soon as you call a plugin command.

K.

[daviddoria]

haha ok i'll put them in the right directory!

is there not a way to call them if they are in a non-standard location?

Can someone show me an example MyGuiDelete script?

-Dave

[korchkidu]

Hi,

You can put your scripts in whatever directory you want. But if it is not in one of the defaut directories accessible from Maya, you have to explicitly add it to your MAYA_SCRIPT_PATH env variable.

basically, your delete script must do something like:

if (menu -exists $mainMenuName)
deleteUI $mainMenuName;

$mainMenuName is a variable containing the name of the menu you created:

$mainMenuName = menu -p $gMainWindow ...;

Hope this helps.
K.

[daviddoria]

about the directories: got it!

now the thing is, I never made a "menu", I just made a "window"

CODE
window -title "MyGUI";

unless I just forgot that i made a menu (if possilby i copied/pasted from somwhere?) I dont think so though, i'll check it out in a couple hours when i get to the lab.

Thanks!

[korchkidu]

Hi,

when you create your window:

$myWin = window -title "Hello World";
showWindow $myWin;

And then, when you delete it:

if (window -exists $myWin)
deleteUI $myWin;

Hope this helps,
K.

[joojaa]

Its porbably smarter to save the names to option vars especially if you intend to call them $myWin which gets corrupted really easily by users.

[korchkidu]

hi,

of course, this is only an example... You have to deal with name conflicts by yourself... But in those cases, it is really easy to deal with this. Simply add predefined prefix for your plugin (your name or whatever you want) and it's done. I prefer keep optionvars for parameters entered in the GUI.

K.

[daviddoria]

getting closer...

I got scripts to run from a directory, had to set some environment variables.

So now I can run MyGUICreate
and it goes in MyGUICreate.mel and runs
global proc MyGUICreate()

in side this proc I do

$MyGUI = window -title "MyGUI";

Then in MyGUIDelete.mel

global proc MyGUIDelete()
{
if (window -exists $MyGUI)
deleteUI $MyGUI;
}

but when I run MyGUIDelete (clearly after running MyGUICreate), maya says
// Error: "$MyGUI" is an undeclared variable.

This seems like a scoping thing, since $MyGUI was created inside { } , but I thought window -exists would take care of that?

Am I still doing something wrong?

Thanks,

Dave

[korchkidu]

Hi,

$myWin is a global variable so you must add the following at the beginning of your script:

global string $myWin;

Hope this helps.
K.

[daviddoria]

ahhh, the key is in MEL you have to redefine the global variable to make it available to another script!!

//create.mel

CODE
global proc MyGUICreate()
{
global string $MyGUI;

$MyGUI = window -height 500 -title "MyGUI";
}

//delete.mel
CODE
global proc MyGUIDelete()
{
global string $MyGUI;
if (window -exists $MyGUI)
deleteUI $MyGUI;
}

Thanks for all the help!!

Dave

[daviddoria]

haha that was a nice aside guys, we got the gui to open/close when the plugin is loaded/unloaded! HOWEVER, the same problem is still occurring, if i unload the plugin and then load it again, when i click the "go!" button on my gui, Maya crashes!

I don't have any undo info:

CODE
// MAKE THIS COMMAND NOT UNDOABLE:
bool SyntheticLiDAR::isUndoable() const
{
   return false;
}

here are some other relevant functions:
CODE
MStatus initializePlugin(MObject obj)
{
    MStatus status;
    MFnPlugin plugin(obj, "David Doria", "2008", "Any");
    status = plugin.registerCommand("SyntheticLiDAR", SyntheticLiDAR::creator);

    plugin.registerUI("SyntheticLiDARGUICreate","SyntheticLiDARGUIDelete");
    return status;
}

MStatus uninitializePlugin(MObject obj)
{
    MStatus status;
    MFnPlugin plugin(obj);
    plugin.deregisterCommand("SyntheticLiDAR");
    return status;
}

class SyntheticLiDAR : public MPxCommand
{
    public:
        SyntheticLiDAR();
        virtual ~SyntheticLiDAR();
        static void* creator();
        bool isUndoable() const;
        MStatus doIt(const MArgList&);
        MStatus undoIt();
};

// CONSTRUCTOR
SyntheticLiDAR::SyntheticLiDAR()
{
}

// DESTRUCTOR
SyntheticLiDAR::~SyntheticLiDAR()
{
}

// FOR CREATING AN INSTANCE OF THIS COMMAND:
void* SyntheticLiDAR::creator()
{
   return new SyntheticLiDAR;
}

Any other clues?
Thanks,

Dave

[korchkidu]

Hi,

do you have any source statement in your MEL scripts ?

K.