Drag to draw one continuous line. Its ends will join.
try a little experiment
Pick the square. Move the harmonic order slowly from 1 to 20. Which parts become sharp last?
Each circle adds a rotating vector. Order H includes frequencies −H to +H, including 0, the center. At order 64, the highest sampled frequency (the Nyquist term) appears once, giving 128 terms. With every term included, the sampled points are reconstructed.
The dashed path uses 128 equally spaced samples of your closed drawing. Error is RMS distance to those samples, in drawing units.