A sunflower places every new seed a fixed angle past the last one. One angle packs them without gaps. Almost every other angle leaves spokes and holes. Drag, nudge, and watch the packing break.
Seed number n sits at distance proportional to √n and at angle n times the turn. If the turn is a simple fraction of a full circle, such as 1/3, seeds line up in a few rays and waste the space between them. The more irrational the turn, the less any ray repeats. The golden angle is 360 × (1 − 1/φ), where φ = (1 + √5) / 2, and its continued fraction is all ones, the hardest number to approximate by a fraction. That is why the arms count steps through 5, 8, 13, 21, as Fibonacci numbers.
The evenness score samples 1,200 points across the disc and finds how far each is from its nearest seed; the 98th percentile of that distance, in units of the seed spacing, is the gap. A gap near 1 scores near 100%, a gap of 5 or more scores 0. Some other angles near a noble ratio also score well at a given seed count, which is why you can find a few more sweet spots by nudging. Everything on this page is computed live from the formula; no external data is used.