\begin{figure}[hb] \vspace* \special{psfile=api/figures/edgeswap.ps hoffset=40} Application of LtFuncMeshingEdgeSwap callback \end{figure}

The edge which is swapped is denoted by the LtVref pair \newline next> of the polygon poly1, and \newline next> of the polygon poly2 (which must not be NULL).

This function is called from LiPrimitiveTriangulate, immediately after the core triangulation operation, in response to the LI_MESH_CRIT_EDGE_SWAPPING criterion, and also during further triangulation, when recently re-triangulated quadrilaterals might introduce edges which need swapping to meet the caller's edge swapping criterion.

If users find that the default callback, LiMeshingEdgeSwap, is not handling some aspect of edge swapping (possibly relating to user-specified properties) then they can write their own callback (perhaps utilising LiMeshingEdgeSwap).

/*
 * writing my own LtFuncMeshingEdgeSwap
 */
LtStatus
my_edge_swap_func (
      LtPrim   prim, 
      LtPoly   poly1, 
      LtVref   vref1, 
      LtPoly   poly2, 
      LtVref   vref2
)
{
   LtStatus   result;

   /* 1: sort the basics */
   result = LiMeshingEdgeSwap(...);

   /* 2: sort my specifics */
   ...

   return ( result );
}