HelixToolkit.Wpf.MeshBuilder.AddRegularIcosahedron C# (CSharp) Method

        public void AddRegularIcosahedron(Point3D center, double radius, bool shareVertices)
        {
            double a = Math.Sqrt(2.0 / (5.0 + Math.Sqrt(5.0)));

            double b = Math.Sqrt(2.0 / (5.0 - Math.Sqrt(5.0)));

            var icosahedronIndices = new[]
                {
                    1, 4, 0, 4, 9, 0, 4, 5, 9, 8, 5, 4, 1, 8, 4, 1, 10, 8, 10, 3, 8, 8, 3, 5, 3, 2, 5, 3, 7, 2, 3, 10, 7,
                    10, 6, 7, 6, 11, 7, 6, 0, 11, 6, 1, 0, 10, 1, 6, 11, 0, 9, 2, 11, 9, 5, 2, 9, 11, 2, 7
                };

            var icosahedronVertices = new[]
                {
                    new Vector3D(-a, 0, b), new Vector3D(a, 0, b), new Vector3D(-a, 0, -b), new Vector3D(a, 0, -b),
                    new Vector3D(0, b, a), new Vector3D(0, b, -a), new Vector3D(0, -b, a), new Vector3D(0, -b, -a),
                    new Vector3D(b, a, 0), new Vector3D(-b, a, 0), new Vector3D(b, -a, 0), new Vector3D(-b, -a, 0)
                };

            if (shareVertices)
            {
                int index0 = this.positions.Count;
                foreach (var v in icosahedronVertices)
                {
                    this.positions.Add(center + (v * radius));
                }

                foreach (int i in icosahedronIndices)
                {
                    this.triangleIndices.Add(index0 + i);
                }
            }
            else
            {
                for (int i = 0; i + 2 < icosahedronIndices.Length; i += 3)
                {
                    this.AddTriangle(
                        center + (icosahedronVertices[icosahedronIndices[i]] * radius),
                        center + (icosahedronVertices[icosahedronIndices[i + 1]] * radius),
                        center + (icosahedronVertices[icosahedronIndices[i + 2]] * radius));
                }
            }
        }

        /// <summary>
        /// Gets a unit sphere from the cache.
        /// </summary>
        /// <param name="subdivisions">
        /// The number of subdivisions.
        /// </param>
        /// <returns>
        /// A unit sphere mesh.
        /// </returns>
        private static MeshGeometry3D GetUnitSphere(int subdivisions)
        {
            if (UnitSphereCache.Value.ContainsKey(subdivisions))
            {
                return UnitSphereCache.Value[subdivisions];
            }

            var mb = new MeshBuilder(false, false);
            mb.AddRegularIcosahedron(new Point3D(), 1, false);
            for (int i = 0; i < subdivisions; i++)
            {
                mb.SubdivideLinear();
            }

            for (int i = 0; i < mb.positions.Count; i++)
            {
                var v = mb.Positions[i].ToVector3D();
                v.Normalize();
                mb.Positions[i] = v.ToPoint3D();
            }

            var mesh = mb.ToMesh();
            UnitSphereCache.Value[subdivisions] = mesh;
            return mesh;
        }