Maya API: Getting dag path from MFnMessageAttribute?

Coding
1

In my node plugin, I would like to grab the start and end joints of a joint chain in order to find the offset matrices between each joint. To do that, I am trying to create message attributes for connecting the joints and figure out the dag path between the two. But I can’t seem to find a way to extract the dag path information from it.

Any ideas on how that can be done? Or should I use something else than MFnMessageAttribute?

Thanks!

2

The connections in the API are done through the MPlug class. MPlug class has a method called MPlug::node() returns the node it belongs to. If you want to find the other end of the connection just do MPlug::connectionByPhysicalIndex(0) which returns the target MPlug, then call MPlug::node() on that.

Once you have the MObject returned by MPlug::node() just call the static method of MDagPath::getAPathTo( MObject &) and it returns a MDagPath for you :slight_smile:

This was all written by checking the C++ API, I’ve used these before but that was probably 3-4 month ago, so just try it out, should work!

3

Oh I see, that really helps, thank you very much! :p:

4

Ah don’t mention it :slight_smile:

Incase someone else wonders the MPlug is received through the function set class MFnDependencyNode, also inherited by MFnDagNode, MFnMesh etc etc.
Every DAG node is a Dependency node :slight_smile:

5

Hello ,

nothing original here , just a snippet inspired by the MPxDeformer documentation


MObject thisNode = thisMObject();

//let say that we have on your node an inputColor attribute
// inputColor here is an MObject that reference it

MPlug imagePlug (thisNode,inputColor);

if ( imagePlug.isConnected() == true ) // is there something feeding this input attribute ?
{
    MPlugArray connectedPlugs;
    connectedPlugs.clear();
    imagePlug.connectedTo(connectedPlugs, true, false);

    if ( connectedPlugs.length() > 0 )
   {
        MObject textureNode = connectedPlugs[0].node(); // <-- you cant have in maya multiple attributes connected to the same destination attribute
    }
}
6

Just curious ,
you want to step outside your node to retrieve a dagPath in order to extract matrix informations?

Have you though of creating an input matrix attribute and connect your transform/joint matrix into it?

7

[QUOTE=cedricB;14784]Just curious ,
you want to step outside your node to retrieve a dagPath in order to extract matrix informations?

Have you though of creating an input matrix attribute and connect your transform/joint matrix into it?[/QUOTE]

Actually when I posted I was going in the wrong direction – I wanted to create a dependency node that takes in the first and last joints of a hierarchy (via message attributes) and modify their transformations (seems to be a really bad idea). I am now going to do that through a constraint instead so I am not using message attributes anymore.

It is still good to know how to find out the dagPath from a message nonetheless, so thanks! :slight_smile: