Forcing triangulation of mesh in MAYA Plugin

[Bernhard Glück]

Hi !

I am writing a MAYA Exporter plugin, that exports all mesh nodes (
polygonal shapes ) of a scene to a propreiatary mesh format, used by a
game graphics engine.

I get all the MFnMesh nodes and then want to write out the data.
However all
objects seem to consist out of quads and not triangles but i need
triangles so
that i can later calculate triangle strips out of them to speed up
rendering in realtime. I can't put my own algorithm , because i need
the EDGE data of a given mesh too ( to aid shadow volume calculation )

So HOW can i force the triangulation ( like Polygon->Triangulate )
from my C++ Plugin ? I don't want to have the artist to have to
triangulate manually ? Is there a way to do this with a given
MFnMesh..

Another problem I walk the DAG, and i seem to get TWO Mesh objects for
any Polygon mesh... here is my DAG walk code:

MStatus exportIrisBrush::doIt( const MArgList& args )
//
// Description:
// implements the MEL exportIrisBrush command.
//
// Arguments:
// args - the argument list that was passes to the command from MEL
//
// Return Value:
// MS::kSuccess - command succeeded
// MS::kFailure - command failed (returning this value will cause the
// MEL script that is being run to terminate
unless the
// error is caught using a "catch" statement.
//
{
MStatus status = MS::kSuccess;

// Create a Dag iterator
MItDag dagIterator;
cout << "Starting the Dag walk ...\n\n";

// Walk the Dag
for ( ; !dagIterator.isDone(); dagIterator.next() )
{
// Get the path to the node
MDagPath dagPath;
status = dagIterator.getPath( dagPath );

// Create Dag node
MFnDagNode dagNode( dagPath,&status );

// Output debug info
cout << "Node: " << dagNode.name().asChar() << "\n";
cout << "Path: " << dagPath.fullPathName().asChar() << "\n";

// Check if we have a mesh node
if (dagPath.hasFn(MFn::kMesh))
{
MFnMesh mesh ( dagPath );

exportMesh ( mesh );
}

cout << "\n\n";
}

// Since this class is derived off of MPxCommand, you can use the
// inherited methods to return values and set error messages
setResult( "exportIrisBrush command executed!\n" );

return status;
}

so when i create a Polygonal sphere i get a MESH node for it twice !!
PfnSpher and PfnSphereShape ??? How can i avoid this ?

Thanks in advance
Bernhard Glück

[Anim8life]

>
>I get all the MFnMesh nodes and then want to write out the data.
>However all
>objects seem to consist out of quads and not triangles but i need
>triangles

You can tessellate to either quads or triangles...I currently do this for an
rtg export that I'm doing for a game import.

>Another problem I walk the DAG, and i seem to get TWO Mesh objects for
>any Polygon mesh..

there is are 2 nodes/components per object...a "transforms" and a "shape" node
(me thinks I have the terminology right)...

[Bernhard Glück]

grif...@aol.com (Anim8life) wrote in message news:<20020111144817...@mb-mq.aol.com>...

> >
> >I get all the MFnMesh nodes and then want to write out the data.
> >However all
> >objects seem to consist out of quads and not triangles but i need
> >triangles
>
> You can tessellate to either quads or triangles...I currently do this for an
> rtg export that I'm doing for a game import.

I knew that, i just asked how i can tesselate to triangles from within
my PLUGIN ... I know how to do it in MAYA itself ( using MEL or the UI
)

>
>
> >Another problem I walk the DAG, and i seem to get TWO Mesh objects for
> >any Polygon mesh..
>
> there is are 2 nodes/components per object...a "transforms" and a "shape" node
> (me thinks I have the terminology right)...

Hm ok that i understood too, but why do both objects support the
MFnMesh Interface ? I mean When one is the transform .. ok but it
should not support the MFnMesh interfaces since it has no mesh .....
How should i distinguis between the two ?

[Bernhard Glück]

Addendum question:

Is there also a way to convert NON MESH nodes ( like NURBS surfaces or
Paint Effects ) to polygonal ones with the MAYA API ? (C++ not MEL
please )

And are all MESH nodes stored as quads ? Because if yes i can do the
triangulation myself ..... otherwise the same question as before
persists...