The number of triangles in the sub-mesh
The offset of the vertices in the NavMeshTile detailVertices array.
If the base index is between 0 and NavMeshTile.vertices.length, this is used to index into the NavMeshTile vertices array.
If the base index is greater than NavMeshTile.vertices.length, it is used to index into the NavMeshTile detailVertices array.
This allows for detail meshes to either re-use the polygon vertices or to define their own vertices without duplicating data.
The number of vertices in thde sub-mesh
The offset of the triangles in the NavMeshTile detailTriangles array