One of the methods for mesh generation provided in GMS is triangulation. New elements are constructed by triangulating a set of nodes. The nodes are connected with a series of edges to form a triangulated mesh as shown in the figure below. A set of nodes can be triangulated by first selecting either the Create Linear Triangle Element tool and then selecting the Mesh|Triangulate command. If some of the nodes have been selected, only the selected nodes are triangulated. If no nodes have been selected, all of the nodes are triangulated. The algorithm that is used to triangulate nodes ensures that the triangulated mesh satisfies the Delauney criterion.
When new nodes are inserted into the interior of a triangular element and the Insert nodes into triangulated mesh option is set in the Node Options dialog, the new node is incorporated into the triangulation and the edges of triangles in the region adjacent to the new node are swapped if necessary in order to satisfy the Delauney criterion.
Related Links:
Creating 2D Meshes