function cactus(x, y, r, i) {
if (r > minR) {
let list = [];
list.push(circle(x, y, r, scheme[i]));
for (let theta = 0; theta < 2 * pi; theta += pi / 2) {
list.push(
cactus(
x - xSpacing * sin(theta),
y - ySpacing * cos(theta),
rScaling * r,
i + 1
)
);
}
return list.flat();
}
}