SVG Blob Generator

If your blob still looks like a circle, add points — not randomness

The usual complaint about a blob generator is that turning randomness all the way up still produces something like a slightly squashed circle. The randomness slider is not the problem. The point count is, and the effect is sharper than it looks.

Testing whether a generated shape has a dent anywhere — whether it is concave rather than convex — across both settings, as a percentage of shapes with at least one dent:

Three and four points never dent. Not rarely — never: twenty thousand shapes at maximum randomness produced not a single concave one. With points spaced evenly by angle and only their distance from the centre varying, three or four of them cannot describe a concave outline, so the curve through them stays convex whatever the radii are.

Five points can, but only at the very top of the range. Eight is where randomness starts behaving like a control rather than a suggestion — 88% at the halfway setting. Twelve dents 37% of the time even at the lowest.

The two sliders do genuinely different jobs

That table is really a statement about which shapes are reachable. The point count decides the space of possible outlines; randomness decides how far into that space you travel. Turning randomness up with too few points does not give you an interesting blob, because every shape within reach is convex — it gives you a lopsided circle, which is exactly what people describe.

So the practical rule is short. If you want an organic shape with lobes and inlets, start at eight points and use randomness to taste. If you want a soft rounded pebble, four or five points is the right choice and randomness genuinely is the only control you need — there is nothing else it can do at that count, which is a feature rather than a limitation.

One thing the numbers also rule out, which is worth saying because it is the natural worry: the curve does not tie itself in knots at high randomness. Testing for self-intersection across the same grid found none at any point count or setting — the shape stays a simple closed curve throughout. Whatever comes out is always a valid outline; the only question is whether it is an interesting one.