static VertexPositionTexture()
        {
            VertexElement[] elements = new VertexElement[] { new VertexElement(0, VertexElementFormat.Vector3, VertexElementUsage.Position, 0),
                                                             new VertexElement(12, VertexElementFormat.Vector2, VertexElementUsage.TextureCoordinate, 0),
                                                           };
            VertexDeclaration d = new VertexDeclaration(20, elements);

            VertexDeclaration = d;
        }
 public VertexDeclaration(int vertexStride, VertexElement[] elements)
 {
     this.elements = elements;
     this.vertexStride = vertexStride;
 }
        public VertexDeclaration(VertexElement[] elements)
        {
            this.elements = elements;

            throw new NotImplementedException("calculation of VertexStride not implemented");
        }