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

        public void AddQuads(
            IList<Point3D> quadPositions, IList<Vector3D> quadNormals, IList<Point> quadTextureCoordinates)
        {
            if (quadPositions == null)
            {
                throw new ArgumentNullException("quadPositions");
            }

            if (this.normals != null && quadNormals == null)
            {
                throw new ArgumentNullException("quadNormals");
            }

            if (this.textureCoordinates != null && quadTextureCoordinates == null)
            {
                throw new ArgumentNullException("quadTextureCoordinates");
            }

            if (quadNormals != null && quadNormals.Count != quadPositions.Count)
            {
                throw new InvalidOperationException(WrongNumberOfNormals);
            }

            if (quadTextureCoordinates != null && quadTextureCoordinates.Count != quadPositions.Count)
            {
                throw new InvalidOperationException(WrongNumberOfTextureCoordinates);
            }

            Debug.Assert(quadPositions.Count > 0 && quadPositions.Count % 4 == 0, "Wrong number of positions.");

            int index0 = this.positions.Count;
            foreach (var p in quadPositions)
            {
                this.positions.Add(p);
            }

            if (this.textureCoordinates != null && quadTextureCoordinates != null)
            {
                foreach (var tc in quadTextureCoordinates)
                {
                    this.textureCoordinates.Add(tc);
                }
            }

            if (this.normals != null && quadNormals != null)
            {
                foreach (var n in quadNormals)
                {
                    this.normals.Add(n);
                }
            }

            int indexEnd = this.positions.Count;
            for (int i = index0; i + 3 < indexEnd; i++)
            {
                this.triangleIndices.Add(i);
                this.triangleIndices.Add(i + 1);
                this.triangleIndices.Add(i + 2);

                this.triangleIndices.Add(i + 2);
                this.triangleIndices.Add(i + 3);
                this.triangleIndices.Add(i);
            }
        }