Definition: A System, Not an Image
A generative system is a set of rules that, when executed, produce output — image, sound, text, behaviour. The artist designs the rules; the system produces the instances.
Three Ingredients
Rules: conditional or repetitive instructions that apply locally but produce global behaviour.
Randomness: not chaos — a controlled variation space. random(20, 80) produces a number between 20 and 80. The artist defines the limits.
Emergence: the most fascinating phenomenon — complex global behaviours that nobody programmed, appearing from the interaction of local rules. Conway's Game of Life: 3 simple rules produce configurations that move, oscillate, generate information.
A Minimal Example
let x, y;
function setup() { createCanvas(400, 400); x = width/2; y = height/2; }
function draw() {
x += random(-3, 3); y += random(-3, 3);
x = constrain(x, 0, width); y = constrain(y, 0, height);
stroke(55, 227, 195, 80); point(x, y);
}
Three rules. Each run produces a different trace. The global structure (Brownian motion) emerges from local rules.
The Artist's Central Question
What do I control? What do I leave to the system?
Too much control: the system becomes an execution tool, not an exploration space. Too little control: no artistic signature. The right balance: the artist is sometimes surprised by what their own system produces.