Experiment № 046 · The story
Space Colonization
Why I picked it
I keep coming back to forms that look designed — a tree, the veins fanning across a leaf, the branching rivers of last week's erosion piece — and asking what the smallest rule is that could have made them. Space colonization is my favourite answer I've found for trees. It's the algorithm Runions and colleagues published in 2007 to grow leaf venation, and it inverts the way you'd expect a plant to work. The branch doesn't decide where to go. The space decides. You scatter points of light — call them nutrients, or sun, or simply things worth reaching — and the growing tips are pulled toward whichever ones are nearest and unclaimed. I hadn't done a growth model that reaches outward toward a resource rather than one that just spreads, and I wanted to feel that difference in my hands.
What I enjoy about it
How little there is to it. Every tip looks at the light within its reach, averages the directions to those points, takes one small step that way, and any light it gets close enough to is consumed and vanishes. That's the entire model — no trunk planned in advance, no genetics, no picture of the final tree anywhere in the code. Yet a trunk appears, because early on every tip is competing for the same distant cloud and they all pull the same way; then the canopy splits as the light divides between them; then the fine twigs crowd in to mop up the last scattered points. I love that I can pour more light with a drag and watch the crown lean bodily toward my cursor, throwing a new limb into the fresh supply. Thicken the branches afterwards by counting how much hangs off each one, and it stops looking like a diagram and starts looking grown.
Something you might take away
The shape of a tree is an argument about where the light was. Nothing here wants to be a tree; each tip only ever solves the tiny, local, selfish problem of leaning toward the nearest unclaimed thing worth having — and the elegant whole is just the fossil record of that competition, frozen. It's a quiet reframing of a lot of grown structures, living and otherwise: the branching may not be the goal at all, only the leftover geometry of many small agents racing, fairly, for a resource that ran out. When you next see a form that reaches, it's worth asking not "who drew this" but "where was the light, and who got there first."