About To Delete Callback And Undo Problem

[psychoswim]

I have a callback setup to watch for the deleting of an input node to my node. When the connection is broken, my custom node is then deleted correctly. If I try to undo, it works fine also and the connections are back to where they were. The problem is that if I then try to delete the node again (after the undo), then it looks like the MDGModifier used in the callback is already doing calls from the previous undo??
Just deleting one node runs the callback once the 1st time, but twice after the undo...

delete curve -> delete custom node : OK
delete curve -> delete custom node -> undo -> curve and custom node are OK
delete curve -> delete custom node -> undo -> delete curve -> ERROR (several messages saying that shape x does not exist)

any suggestions??

[joojaa]

stop using the callback use the setExistWithoutInConnections( false ) definiton instead.

[daniel-faust]

Yes, but a problem with the setExistWithoutInConnections is that you need to break absolutely all connections to the node, and sometimes this is not desirable.

Sometimes the disconnection of one specific connection should be what triggers the deletion.

The problem psychoswim sounds familiar to me, it has something to do with the undo queue and I'll review my code to see into what problems i run back at the time when I was doing this.

[daniel-faust]

What callback are you using and what methods are you calling to delete the node?

[psychoswim]

Here's one example:

My custom node is called clothWrinkle. This node takes input from a nurbs curve and a triangular mesh. If the connection is broken between the curve and the node, then I need to delete this node.

Right now, I'm using an aboutToDelete callback to watch the curve node for deletion (I set it up in connectionMade). In the callback, I use the modifier to disconnect the curve from the node (as it seems the connection is still there on the node's side) and disconnect the mesh from the curve (mod.disconnect). I set setExistWithoutInConnections(false) so the node is then set to be deleted.

I have a second custom node that takes as input the triangular mesh, as well as multiple clothWrinkle nodes and produces a resulting mesh. When all the clothWrinkle nodes are deleted then this node needs to be deleted. I do the same thing in the callback (disconnect connections), and I also add the triangular mesh to its original shading group. In this callback, I also delete the parent transform node.

So, all the operations I use are mod.disconnect except for 1 mod.deleteNode and 1 of each of "sets -rm" and "sets -add".

Node 1 (clothWrinkle):
input -> curve, mesh
output -> mesh

Node 2
input -> mesh, multiple clothWrinkle nodes
output -> mesh

It looks like maybe the modifier queue holds multiples for the set operations since when the callback is called after an undo, I get errors saying the polySurfaceShape (output of node 2 that is connected to the shading group) does not exist.

thanks for any help

CODE

void ClothWrinkleNode::aboutToDeleteCB( MObject &node, MDGModifier &mod, void* clientData )
{
  MStatus stat;
  MFnDependencyNode nodeFn;
  MPlug plug;
  MPlugArray plugs;

  nodeFn.setObject( node );
  MString plugName = nodeFn.findPlug( "worldSpace" ).name();

  if( node.apiType() == MFn::kNurbsCurve )  
  {
    MObject obj;

    // Find clothWrinkle node without input curve connection

    MSelectionList selection;
    MGlobal::executeCommand( "select -r ls -type \"clothWrinkle\"" );
    MGlobal::getActiveSelectionList( selection );

    for( int i = 0; i < (int) selection.length(); i++ )
    {
      selection.getDependNode( i, obj );
      nodeFn.setObject( obj );
      plug = nodeFn.findPlug( "inCurve" );
      plug.connectedTo( plugs, true, false );
        break;
    }
  }

  // inCurve connection (if not already disconnected)

  plug = nodeFn.findPlug( "inCurve" );
  plug.connectedTo( plugs, true, false );
  if( plugs.length() > 0 )
    mod.disconnect( plugs[0], plug );

  // inMesh connection

  plug = nodeFn.findPlug( "inMesh" );
  plug.connectedTo( plugs, true, false );
  if( plugs.length() > 0 )
    mod.disconnect( plugs[0], plug );

}

[daniel-faust]

Keep in mind that you are changing Maya's state with the MGlobal::executeCommand( "select -r ls -type \"clothWrinkle\"" ); call

use MDGModifier::commandToExecute so that the selection get's undone / redone correctly. This may be the only cause, but maybe there are more things to keep in mind. This is just to get you started because I don't have much time now.

[psychoswim]

Okay

I replaced the executeCommand by selection.add( "clothWrinkle*" ) so not to change the graph and it doesn't change anything. If I use MDGModifier::commandToExecute to do my selection, then I would need the result immediately but the mod.doIt() is only called when the function returns. Can I call it myself inside the callback?

Looks like the other problem is when I want to delete the parent transform node (the output mesh was created with this node as parentOrOwner) and it complains about the child shape missing...

CODE
  ... Node 2 aboutToDeleteCallback

  // outMesh

  plug = nodeFn.findPlug( "outMesh" );
  plug.connectedTo( plugs, false, true );
  MObject polySurface = plugs[0].node();
  if( plugs.length() == 0 )
  {
    MGlobal::displayError( "wrinkledCloth is not connected to a mesh shape" );
    return;
  }
  mod.disconnect( plug, plugs[0] );

  // disconnect and reconnect shading group

  MObjectArray shaders;
  MIntArray shaderIndices;

  dagFn.setObject( polySurface );
  MDagPath dagPath;
  dagFn.getPath( dagPath );
  int instNum = dagPath.instanceNumber();

  MFnMesh meshFn( polySurface );
  meshFn.getConnectedShaders( instNum, shaders, shaderIndices );

  MFnSet sgFn( shaders[0] );
  MString setName = sgFn.name();
  nodeFn.setObject( baseClothMesh );
  MString baseClothName = nodeFn.name();
  nodeFn.setObject( polySurface );
  MString polySurfaceName = nodeFn.name();
  MObject parent = dagFn.parent( 0 );

  // Add base cloth to shading group (don't need to explicitely remove polySurface though)

  mod.commandToExecute( MString( "sets -add " ) + setName + " " + baseClothName );
  mod.commandToExecute( MString( "sets -rm " ) + setName + " " + polySurfaceName );

  // Delete parent wrinkledCloth transform

  nodeFn.setObject( parent );
  mod.commandToExecute( MString( "delete " ) + nodeFn.name() );
//   mod.deleteNode( parent );

}

If I comment out the line mod.commandToExecute( MString( "delete " ) + nodeFn.name() then undo/redo/delete works fine except that the polySurfaceShape and its parent transform are not deleted.

ETA: If I create 2 curves and delete both, then undo, then try deleting again in the opposite order, then the selection is apparently messed up.

I'll try to fix the selection problem some other way.

[joojaa]

QUOTE(Daniel_Faust @ 11/22/06, 06:07 PM) [snapback]253057[/snapback]
Sometimes the disconnection of one specific connection should be what triggers the deletion.

Ok so what your saying is that its desireable to have nodes that work unlike all other maya nodes, in respect to functions taht arent related to the nodes design but gui thats should eb same to all? And in this case if i want to trasfeer a node with same values to another shape i cant jut disconnect and reconnect.

I mena it sounds reasonable for keeping a tidy scene but thing is its not necceserily so. Because it works unlike other maya nodes yu coud bet the td who deletes the connection manuly to trasfeer the node is going to curse you guys down to the lowest pits of hell.

In fact the maya internal tidying mechanism works a bit differently, it deletes the node that has no sane connections comming out of itt IF and only if the node that connected into it was deleted (it gets deletted fully if theres no connection inbound unless you have switched the global tidy off), its not just the act of deleting the connection as you ca cut the connection off without the deletion occouring. This mekas working with the grah much easier as i can controll when i suppose the thing si going to dissapear. However with your approach its actualy not working like one would expect. And thats allways a very good indicator of a job well done

[daniel-faust]

Good point, joojaa, it had never come to my mind. Thanks for bringing this up and make me doubt of the beauty of the solution I implemented (damn, I thought that chapter was over).

[psychoswim]

Thanks to both of you for your answers.

I set setExistWithoutInConnections( false ) for both my custom nodes. Now, when the input curve is deleted, I disconnect the input mesh at the same time so my node is removed automatically (this node cannot exist with only one of the 2 inputs). I do the same for the 2nd custom node and everything works ok (so I don't delete anything explicitely anymore).

I have a question though. The mesh created by my 2nd node is fed into a polySurfaceShape node that is added to the shader group. This node has a transform node that was used as parentOrOwner in meshFn.create(). When my node gets deleted, the shape has no remaining input or output connections (and I removed it from the shader set). Why does it not get deleted? The resulting hypergraph has the polySurfaceShape without any inbound or outbound connections, and the parent transform as well.

thanks again
michelle