Common helper methods used during tessellation of various patterns. These might be helpful when writing custom tessellation patterns. Takes a triangle defined by three vertices and a TessellationLevel value. For each corner of the outer triangle, an inner triangle corner is produced at the intersection of two lines extended perpendicular to the corner's two adjacent edges running through the vertex of the subdivided outer edge nearest to that corner. U O / \ O - triangle corner / \ x - closest vertex to the corner inserted along the edge during tessellation / \ + - inner vertex resulting from intersection of two lines extened perpendicular to the edges x x / . . \ / + \ / innerU \