MItDag Reverse Traversal?

[shredder]

Hey guys, I am trying to figure out how to traverse UP the hierarchy from a specific node till I find another node. I cant figure out how to do that in API.

In Mel I would do something like this

 
string $testJoint = "joint5";
string $parentNode = "joint2";
 
string $parents[];
 
while ($parents[0] != $parentNode)
{
$parents = `listRelatives -p $testJoint`;
$testJoint = $parents[0];
print $parentNode;
print $parents;
$c++;
}

[whisperwing]

MStatus stat;
MObject yourJointObject;
MFnDag fnDag(yourJointObject, &stat);
if (stat == MS::kSuccess)
{
  MDagPath path;
  stat = fnDag.getPath(path);
  unsigned int pathCnt = path.pathCount();
  while (pathCnt > 0)
  {    // keep calling pop(), get the MObject from node() and check the name
    pathCnt --;
  }
}

[shredder]

MStatus stat;
MObject yourJointObject;
MFnDag fnDag(yourJointObject, &stat);
if (stat == MS::kSuccess)
{
  MDagPath path;
  stat = fnDag.getPath(path);
  unsigned int pathCnt = path.pathCount();
  while (pathCnt > 0)
  {    // keep calling pop(), get the MObject from node() and check the name
    pathCnt --;
  }
}

Are you sure this works?
first I am sure this is just a typo "MFnDag fnDag" , should be MFnDagNode, right?

but when I run this code exactly like you have it here..
unsigned int pathCnt = path.pathCount();
pathCnt = 1;
and its on the 5th joint in a chain..
if I do a cout on path.fullPathName();
I get this return.
|joint1|joint2|joint3|joint4|joint5

so the pathCount is 1 but there is clearly 5 items in the path

[joojaa]

I think its rather meant as pseudecode than actual strict code to use. This is a forum not a support service, you cant expect people to invest too much time in your problems so most stuff are swinged VERY quickly. Your actually supposed to bring the knowhow yourself, and use the manual to actually do thw heavy lifting.

Which usually beraks down on the api forum because so many users with clearly too little know how ask api questions. Which would be hanlded on any of the other forums adequately but as a api question they just take way too much time to answer.

[shredder]

Joojaa, I get it that he didnt spend a whole day writting it out. I did not expect him to write my whole plugin for me by any means. However, he did post code, that code does not seem to work. I tried other variations and couldnt get it to work either. I did not just copy and paste that in my plugin and say "hey this doesnt work". I posted what I found here to try and figure out WHY it wasnt working. Looking at the code, I would think it should work. But clearly, pathCount and fullPathName do not return what I would think are the correct data. Looking at the fullPathName, you would think that pathCount would return 5, not 1.

Where you are wrong is, this is a forum, correct. A forum where people go to ask questions when they cant get something working. I did not specifically ask him for support. I asked a community if they know how to do something. That community posted something that doesnt seem to be the answer, so am I just supposed to go "ok". No, to learn I am going to ask more questions as to why it doesnt work.

If this forum isnt for people to come in and ask questions, then what is it for?  If everyone brought the know how to do everything in the API, then what good is the API forum?

How did I not ask the question properly? Get off your high horse.. if you dont have something positive to add, then dont post

[nowayfra]

The method MDagPath::pathCount() doesnt return the depth of the current path, it only gives you the total number of paths represented by the current MDagPath instance. This is mostly only one path, two for example if the node resides in the underworld, a curve painted on a live made nurbs surface etc. The path with index 0 then is the 3D path, path 1 the path inside the shape at the end of path 0.
To get upstream try this: (slapped it together without error checking stuff)

    MSelectionList activeList;
    MGlobal::getActiveSelectionList(activeList);

    MItSelectionList selIter( activeList );

    for( ; ! selIter.isDone(); selIter.next())
    {
        MObject obj;
        MDagPath dagPath;
        selIter.getDagPath(dagPath);
        MFnDagNode dagNodeFn(dagPath);
        for(uint i=dagPath.length(); i>0; --i)
        {
            obj = dagNodeFn.parent(0);
            dagNodeFn.setObject(obj);
            cout << "path depth: " << (i - 1) << " " << MString(dagNodeFn.fullPathName()).asChar() << endl;
        };
    };

[shredder]

The method MDagPath::pathCount() doesnt return the depth of the current path, it only gives you the total number of paths represented by the current MDagPath instance. This is mostly only one path, two for example if the node resides in the underworld, a curve painted on a live made nurbs surface etc. The path with index 0 then is the 3D path, path 1 the path inside the shape at the end of path 0.
To get upstream try this: (slapped it together without error checking stuff)

    MSelectionList activeList;
    MGlobal::getActiveSelectionList(activeList);

    MItSelectionList selIter( activeList );

    for( ; ! selIter.isDone(); selIter.next())
    {
        MObject obj;
        MDagPath dagPath;
        selIter.getDagPath(dagPath);
        MFnDagNode dagNodeFn(dagPath);
        for(uint i=dagPath.length(); i>0; --i)
        {
            obj = dagNodeFn.parent(0);
            dagNodeFn.setObject(obj);
            cout << "path depth: " << (i - 1) << " " << MString(dagNodeFn.fullPathName()).asChar() << endl;
        };
    };

That worked perfect, exactly what I was looking for. Thanks for your help!!

[joojaa]

If this forum isnt for people to come in and ask questions, then what is it for?  I

No thats not what im saying, im saying you just should say that its not apparent in your post that you did any deep introspection on the subject. Its should allways show that you have actually done some reasearch before you ask. It just doesnt show, i was just pointing that out to you.

Besides it woula actually be much more productive to talk about strategies with you instead of port this please.

Looking at the fullPathName, you would think that pathCount would return 5, not 1.

Well no thast not what its meant to do. I grant you his code doesnt make sense but thats just pseudocde wirtten in c form which I agree is bad. But that might also be acorruption on his side. Pseudocode shows the idea its not even supposed to work.

But yes his code is sortof smarter than nowayfra's tough he too didnt read the manual.

Instad of using pathCount() he should have used length() and offcourse write out the path.pop() an it would have worked So he was actually one step away form the right answer provided that you knew how to input a name to the api functions in first place.

Api code in python to show your mel codes spirit (port yourself back to c should be trivial):

import maya.OpenMaya as om
list = om.MSelectionList()
list.add("joint5")
list.add("joint2")
 
child = om.MDagPath() 
list.getDagPath(0,child)
 
paren = om.MDagPath() 
list.getDagPath(1,paren)
 
pathCnt = child.length()
print pathCnt
# never compare while (paren != child) 
# or you might make a long loop that will fail by accident!
while (pathCnt > 0): 
    print child.fullPathName()
    child.pop()
    if paren==child:
      break;
    pathCnt -= 1
print child.fullPathName()

PS: its not entirely usefull to port mel to api because they dont overalp in function