IMesh::VertexWeld

Removes duplicated vertices from the mesh.

   HRESULT VertexWeld(
   float epsilon,  
   BOOL bAll  

);

epsilon

[in] Specifies the smallest distance that can be between 2 vertices and still be considered separate.

bAll

[in] A non-zero value will perform the operation on the entire mesh, otherwise the operation applies to only the selection.