AbcExport: How to export the bbox of hierarchical xform nodes?

[Anonymous]

How to export the bbox of hierarchical xform nodes?

Hi all,

I'm going to extend Maya2014 AbcExport plugin to export the bbox of hierarchical xform nodes. But I encountered some problems.

For example, here are the hierarchical xform nodes in maya:

group3                              (xform)
   |___group1                       (xform)
   |      |___pCube1                (xform)
   |      |      |____pCubeShape1   (polygon)
   |      |___pCube2                (xform)
   |             |____pCubeShape2   (polygon)
   |___group2                       (xform)
   |      |___pCube3                (xform)
   |      |      |____pCubeShape3   (polygon)
   |      |___pCube4                (xform)
   |             |____pCubeShape4   (polygon)

I'm going to export the bbox of every xform node, e.g. group1, group2, group3, pCube1, pCube2, pCube3, pCube4.

I modified MayaTransformWrite.cpp like this:

----------------------------------
class MayaTransformWriter
{
    ...
    Alembic::Abc::OBox3dProperty myTransBoxProp;    
    MDagPath myTransDag;
}
----------------------------------
MayaTransformWriter::MayaTransformWriter(Alembic::AbcGeom::OObject & iParent, ...)
{
    if (iDag.hasFn(MFn::kJoint))
    {
    ...
    }else{
            ...
            mAttrs = AttributesWriterPtr(new AttributesWriter(cp, up, obj, trans, iTimeIndex, iArgs));
            
            myTransDag = iDag;// save current dag to myTransDag
            MyTest(myTransDag);
            ...
    }
    ...
}
----------------------------------
MayaTransformWriter::MayaTransformWriter(MayaTransformWriter & iParent, ...)
{
    if (iDag.hasFn(MFn::kJoint))
    {
    ...
    }else{
            ...
            mAttrs = AttributesWriterPtr(new AttributesWriter(cp, up, obj, trans, iTimeIndex, iArgs));
            
            myTransDag = iDag;// save current dag to myTransDag
            MyTest(myTransDag);
            ...
    }
    ...
}
----------------------------------
void MayaTransformWriter::write()
{
    size_t numSamples = mAnimChanList.size();
    if (numSamples > 0)
    {
        ...
        mSchema.set(mSample);

        MyTest(myTransDag);// use myTransDag
    }
}
----------------------------------
void MayaTransformWriter::MyTest(MDagPath iDag)
{
    MStatus status;

    unsigned int childCount = iDag.childCount(&status);
    CHECK_MSTATUS(status);

    if(childCount > 0)
    {
        MObject child(iDag.child(0, &status));     CHECK_MSTATUS(status);

        MFnDagNode fnChildDagNode(child, &status);     CHECK_MSTATUS(status);

        MDagPath childDagPath; status = fnChildDagNode.getPath(childDagPath);  CHECK_MSTATUS(status);//
        printf("fnDagNode.getPath(&): %s\n", childDagPath.fullPathName().asChar());
        if(!childDagPath.isValid(&status))
        {
            CHECK_MSTATUS(status);
            childDagPath = fnChildDagNode.dagPath(&status);     CHECK_MSTATUS(status);//
            printf("fnDagNode.dagPath()=%s\n", childDagPath.fullPathName().asChar());
        }
        assert(!childDagPath.isNull() && "childDagPath is null");

        if(childDagPath.apiType() == MFn::kMesh) // child node is a mesh shape node
        {
            setAbcBBoxFromNode(fnChildDagNode);
        }else{
            if(isAnimated())
            {
                setAbcBBoxFromNode_animation(iDag); // <---- export the bbox for animation xform node
                //setAbcBBoxFromNode(iDag);
            }else{
                setAbcBBoxFromNode(iDag);
            }

        }

    }else{
        printf("it has no child\n");
    }
}

void MayaTransformWriter::setAbcBBoxFromNode(const MFnDagNode &fnDag)
{
    transBoxProp = mSchema.getChildBoundsProperty();
    MBoundingBox bbox;
    bbox = fnDag.boundingBox();
    Alembic::Abc::V3d min(bbox.min().x, bbox.min().y, bbox.min().z);
    Alembic::Abc::V3d max(bbox.max().x, bbox.max().y, bbox.max().z);
    Alembic::Abc::Box3d b(min, max);
    transBoxProp.set(b);
}
void MayaTransformWriter::setAbcBBoxFromNode_animation(const MDagPath &inDagPath)
{
   //  how to export the bbox for animation xform node?
}

setAbcBBoxFromNode() can't handle the animation xform correctly, so I have to implement another setAbcBBoxFromNode_animation() for the animation xform node. I tried several ways but failed.

So my questions are:
- I don't know how to implement function setAbcBBoxFromNode_animation(). Could you give me any clue or any suggestion?
- Is there any simpler method to export the bbox of the hierarchical xform node?

Cheers
yao