Area :: Discussions

Feedback

Tell us what you think of the site.

Send Feedback

AREA
Digital Entertainment
& Visualization Community

Autodesk Media & Entertainment User Community

Latest Blogs

My Oh Maya!
Maya Bonus Tools Resource Page (New Updates)

maxTD
maxTD lives on Vimeo

3D SDK and Scripting Mayhem
The 3ds Max 2013 .NET SDK and MaxSharp Source Code

More Blogs

Software Trials

Autodesk® 3ds Max®

Download Trial

Autodesk® Maya®

Download Trial

Autodesk® Softimage®

Download Trial

Autodesk® MotionBuilder®

Download Trial

Autodesk® Mudbox™

Download Trial

Autodesk® Sketchbook® Pro

Download Trial

Autodesk® Smoke on Mac®

Download Trial

RSS 2.0

ATOM

not all control points (vertices) in a mesh are assigned to a cluster (bone) ?

Rate this thread

Permlink of this thread

johnhp

johnhp
Posted: 08 November 2011 05:42 AM

Total Posts: 1
Joined: 08 November 2011 04:36 AM

I’m trying to load FBX models into Ogre, and so far I have no problem with static meshes, however I haven’t been able to handle skeletal animation yet.

Ogre requires that every vertex in a skinned mesh must be assigned to a bone, however the information that I’m getting from the FBX file doesn’t work out that way.

My question is this: is it OK (in terms of FBX loading) for a skinned mesh to have vertices which are not assigned to any cluster?

The code below shows how I’m accessing vertex bone assignments, and the output when I run the program.

int numVertAssignments = 0;

    int numClusters = 0;

    int numDeformers = 0;

    assert( gMesh );

    numDeformers = gMesh->GetDeformerCount();

    for( int i = 0; i < gMesh->GetDeformerCount(); ++i )

    {

        KFbxSkin *skin = (KFbxSkin*)mesh->GetDeformer( i, KFbxDeformer::eSKIN );

        assert( skin );

        numClusters = skin->GetClusterCount();

        for( int j = 0; j < skin->GetClusterCount(); ++j )

        {

            KFbxCluster *cluster = (KFbxCluster*)skin->GetCluster( j );

            assert( cluster );

            int numIndices = cluster->GetControlPointIndicesCount();

            numVertAssignments += numIndices;

        }

    }

    AV_LOG_INFOL("number of deformers: " << numDeformers);

    AV_LOG_INFOL("number of clusters: " << numClusters);

    AV_LOG_INFOL("number of vertex assignments: " << numVertAssignments);

    AV_LOG_INFOL("number of vertices in mesh: " << gMesh->GetPolygonVertexCount());

info: number of vertices in mesh: 400980

info: number of deformers: 1

info: number of clusters: 64

info: number of vertex assignments: 98673

Replies: 1

I see a couple of issues here. One is that GetPolygonVertexCount is not guaranteed to be (and usually won’t be) the same result as GetControlPointsCount. Cluster weights correspond to control points and not polygon vertices directly. The second issue is that you’re not getting an accurate count of how many vertices are actually weighted, because clusters are likely to reference a single vert more than once in the event that the vert has multiple joint influences.

The appropriate way to handle skinning with deform clusters can be seen in examples\ViewScene\DrawScene.cxx. ComputeLinearDeformation is a good function to start with.

Author: RichWhitehouse

Replied: 10 November 2011 02:07 AM

General

Autodesk 3ds Max

Autodesk Softimage

Autodesk Maya

Autodesk Mudbox

Creative Finishing

Product Communities