Constructing Streak Surfaces for 3D Unsteady Vector Fields: Supplementary Material
Tony McLoughlin, Robert S. Laramee, Eugene Zhang · 2003
In order to simplify the implementation of splitting due to divergence, we test one quad edge at a time and update the topology of the mesh accordingly. For example, Algorithm 1 shows how we update the mesh topology if a quad’s west edge length |EW |> dsep. First we test for an existing T-junction on the west edge. If there is one we use it, otherwise we interpolate a new vertex. Likewise for the east edge. Then we construct a new quad for the north half, as in of Figure 12. Another procedure is called to update the resulting topology (Quad::UpdateNeighborsWest()) shown in Algorithm 2. The methods that handle divergence associated with the other quad edges are similar to Quad::DivideWest(). Figure 12 shows a possible subtle configuration for the Quad::DivideWest() operation. We have to test whether the northwest vertex, VNW, is a T-junction. If it is we change the T-junction’s extra neighbor pointer to point to the newly inserted quad. The