/// <summary>
        /// This is the method that actually does the work.
        /// </summary>
        /// <param name="DA">The DA object is used to retrieve from inputs and store in outputs.</param>
        protected override void SolveInstance(IGH_DataAccess DA)
        {
            MeshGhData hE_MeshData = new MeshGhData();

            if (!DA.GetData(0, ref hE_MeshData))
            {
                return;
            }

            Paramdigma.Core.HalfEdgeMesh.Mesh hE_Mesh = hE_MeshData.Value;

            if (!hE_Mesh.IsTriangularMesh())
            {
                AddRuntimeMessage(GH_RuntimeMessageLevel.Error, "Mesh is not triangular!");
                return;
            }

            List <Vector3d> normals       = new List <Vector3d>();
            List <Point3d>  centroids     = new List <Point3d>();
            List <Point3d>  circumcenters = new List <Point3d>();


            foreach (Paramdigma.Core.HalfEdgeMesh.MeshFace face in hE_Mesh.Faces)
            {
                Paramdigma.Core.Geometry.Vector3d v        = Paramdigma.Core.Geometry.MeshGeometry.FaceNormal(face);
                Paramdigma.Core.Geometry.Point3d  centroid = Paramdigma.Core.Geometry.MeshGeometry.Centroid(face);

                normals.Add(new Vector3d(v.X, v.Y, v.Z));
                centroids.Add(new Point3d(centroid.X, centroid.Y, centroid.Z));
            }

            DA.SetDataList(0, normals);
            DA.SetDataList(1, centroids);
        }
        /// <summary>
        /// This is the method that actually does the work.
        /// </summary>
        /// <param name="DA">The DA object can be used to retrieve data from input parameters and
        /// to store data in output parameters.</param>
        protected override void SolveInstance(IGH_DataAccess DA)
        {
            MeshGhData hE_MeshData = new MeshGhData();

            if (!DA.GetData(0, ref hE_MeshData))
            {
                return;
            }

            Paramdigma.Core.HalfEdgeMesh.Mesh hE_Mesh = hE_MeshData.Value;

            if (!hE_Mesh.IsTriangularMesh())
            {
                AddRuntimeMessage(GH_RuntimeMessageLevel.Error, "Mesh is not triangular!");
                return;
            }

            List <Vector3d> normals = new List <Vector3d>();

            foreach (MeshVertex v in hE_Mesh.Vertices)
            {
                Paramdigma.Core.Geometry.Vector3d vect = new Paramdigma.Core.Geometry.Vector3d();

                switch (Selection)
                {
                case NormalSelection.Equal:
                    vect = Paramdigma.Core.Geometry.MeshGeometry.VertexNormalEquallyWeighted(v);
                    break;

                case NormalSelection.Area:
                    vect = Paramdigma.Core.Geometry.MeshGeometry.VertexNormalAreaWeighted(v);
                    break;

                case NormalSelection.Angle:
                    vect = Paramdigma.Core.Geometry.MeshGeometry.VertexNormalAngleWeighted(v);
                    break;

                case NormalSelection.Gauss:
                    vect = Paramdigma.Core.Geometry.MeshGeometry.VertexNormalGaussCurvature(v);
                    break;

                case NormalSelection.Mean:
                    vect = Paramdigma.Core.Geometry.MeshGeometry.VertexNormalMeanCurvature(v);
                    break;

                case NormalSelection.Sphere:
                    vect = Paramdigma.Core.Geometry.MeshGeometry.VertexNormalSphereInscribed(v);
                    break;
                }

                normals.Add(new Vector3d(vect.X, vect.Y, vect.Z));
            }

            DA.SetDataList(0, normals);
        }