Mesh

Creating a mesh

Mesh creation in Triangle.NET is controlled by three interfaces:

• ITriangulator for triangulating point sets
• IConstraintMesher for triangulating polygons
• IQualityMesher for creating quality meshes of polygons

All three interfaces are implemented by the GenericMesher class (located in the TriangleNet.Meshing namespace).

The following example shows (from left to right) an input polygon, the triangulated point set, the mesh with segments inserted, and the mesh with quality settings applied:

Triangulation algorithms

The triangulation algorithms in the TriangleNet.Meshing.Algorithm namespace include

• Dwyer (Divide & Conquer) (the default algorithm)
• Sweepline (reasonably fast)
• Incremental (slow)

All classes implement the ITriangulator interface, so they can be used to create a mesh from a given point set.

Triangulating a polygon

The easiest way to triangulate a Polygon is to use one of the Triangulate extension methods, which are available through the TriangleNet.Geometry namespace.

These methods make use of the GenericMesher class. It is recommended that you use the extension methods, unless you want to change the default triangulation algorithm, which can be done using the constructor overloads of the GenericMesher class.

Here's a simple example, using the Lake Superior polygon file:

using TriangleNet.Geometry;
using TriangleNet.IO;
using TriangleNet.Meshing;

public static void Example()
{
   // Load polygon from file.
   var polygon = FileProcessor.Read("superior.poly");

   var options = new ConstraintOptions() { ConformingDelaunay = true };
   var quality = new QualityOptions() { MinimumAngle = 25 };

   // Triangulate the polygon
   var mesh = polygon.Triangulate(options, quality);
}

Generating a structured mesh

The GenericMesher provides a static utility function to create structured meshes of rectangular domains:

// Create unit square.
var bounds = new Rectangle(-1.0, -1.0, 2.0, 2.0);

// Generate mesh.
var mesh = GenericMesher.StructuredMesh(bounds, 20, 20);