MEL: How to select a shading network by selecting one member of that network?

Coding
1

Hello everyone,

I’ve made a script that exports materials from a shading scene then imports and assigns the materials to alembics in a lighting scene. The only problem was it didn’t bring in the V-Ray displacement groups! So, instead of writing a script that exports and connects those displacement groups to their proper materials, I’d like to export a shading network by selecting it’s highest node in the network (the place2dTexture node), then select the rest of the network from there, and finally export that selection .

My big problem with solving this issue is I’m not quite sure what commands to use to select the rest of the network once I have the place2dTexture node selected. I usually use pickWalk when I want to move around a selection, but that doesn’t work in this case (as far as I know). I’ve attached an image to help clarify my question. Thank you!


And here’s my code so far:


// select all "place2dTexture" utilities
global proc SelectPlace2dUtilities()
    {
        string $nodesList[];
        
        $nodesList = `ls -type "place2dTexture"`;
        select -add $nodesList;
    }
2

you’ll want to take a look at the listHistory and listConnections commands.

http://help.autodesk.com/cloudhelp/2015/ENU/Maya-Tech-Docs/CommandsPython/listConnections.html

starting with the place2dtexture node you could just recursively list destinations until you run out of nodes.

3 

def get_shader(node):
     return cmds.ls(*cmds.listHistory(node, f=True) or [], type='lambert)  or []

It has to return a list since it’s possible for one node to terminate in multiple shades. If you want the shadingGroup node, instead you could swap in ‘shadingEngine’ for ‘lambert’

4

Great! Thanks guys, I’ll take a look at these options and report back.

5

doh, I should have done that in mel

ls -type lambert listHistory -f 1 $node;