hohehohe2's OpenMaya tutorial
kotamuraa@yahoo.co.jp
9. Handling DG node(basic)
The example at Chapter 7,
There are two nurbs surface in the scene. How can I
change values of
one surface CV positions and not the other, using MFnNurbsSurface
class instance.
The first process was,
1) Get an MObject of the nurbs surface which you want to
change CV positions.
How it can be done wasn't described yet.
In this chapter I will describe the general way of
getting an MObject of a DG node by
its node name.
In this chapter I will also describe
- How to get an MObject of the selected
(active) DG nodes
- How to select (activate) a DG node.
Here selecting (activating) a node means just the
same way as you left click
a scene object or left click a node in the Hypergraph.
Selection list
Let's take a look at a sample program first. It is a
program to display every node which
name starts with "hohehohe2".
---------------------------------------------------------------------
#include <maya/MGlobal.h>
#include <maya/MSelectionList.h>
#include <maya/MFnDependencyNode.h>
MStatus displayHohe::doIt( const MArgList& ){
//Create a selection list, get an MObject
of the nodes which name
//starts from "hohehohe2" in it.
MSelectionList selList;
selList.add("hohehohe2*");
//How many DG nodes are there in the
list?
int numObjs = selList.length();
for (int i = 0; i < numObjs; ++i){
//Get the contents
of the selection list one by one,
//set it to "objHohe".
MObject objHohe;
selList.getDependNode(i
,objHohe);
//Create a function
set, connect to it,
MFnDependencyNode
fnDepHohe(objHohe);
//and display its
name.
MGlobal::displayInfo(fnDepHohe.name());
MGlobal::displayInfo(fnDepHohe.typeName());
MGlobal::displayInfo("");
//Line feed
}
return MS::kSuccess;
}
MStatus displayHohe::redoIt(){return MS::kSuccess;}
MStatus displayHohe::undoIt(){return MS::kSuccess;}
---------------------------------------------------------------------
Here, three classes
- MGlobal
- MSelectionList
- MFnDependencyNode
are used, so three header files are included.
#include <maya/MGlobal.h>
#include <maya/MSelectionList.h>
#include <maya/MFnDependencyNode.h>
Generally when you need to use ****, you need to include
maya/****.h
file.
A class MSelectionList has come out.
This class is a container class ( it's like an array ) to contain
MObjects.
(API manual says MSelectionList implement a list of MObjects)
When the first MSelectionList class instance is created,
MSelectionList selList;
nothing is in the list. But just after it has created,
selList.add("hohehohe2*");
every node which its name start with "hohehohe2" is added to
the list.
Next, get the number of MObjects in the list using MSelectionList::length()
method.
int numObjs = selList.length();
Then create a loop and display it one by one.
for (int i = 0; i < numObjs; ++i){
In the loop, get the i th MObject of the selection list.
MObject objHohe;
selList.getDependNode(i
,objHohe);
Attach a function set to access the node, and
display informations such as node name to the Script Editor.
MFnDependencyNode
fnDepHohe(objHohe);
MGlobal::displayInfo(fnDepHohe.name());
MGlobal::displayInfo(fnDepHohe.typeName());
MGlobal::displayInfo("");
//Line feed
Compile the sample program and execute it.
Name this command plug-in "displayHohe".
First make a nurbs sphere primitive in the scene, rename it to
"hohehohe2Sphere1", and then run "displayHode"
In the Script Editor the following informations will be displayed.
displayHohe;
// hohehohe2Sphere1
// transform
//
// hohehohe2SphereShape1
// nurbsSurface
//
Since the shape node is automatically renamed if you rename an
object (transform node), two node informations are displayed.
P.S.
Note that "selection"(left click and activate a scene object)
and "selection list"
are completely different thing.
"selection" can be done within a plug-in code using "selection list",
but do not
mix them up.
Global selection list
I haven't written this yet.
(-_-)
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2003, Koichi Tamura. All Rights Reserved.