fractal

float theta;

void setup() {
  size(750, 750);
  //strokeWeight(1);
  //noStroke();
  //fill(0,45);
}

void draw() {
  background(255);
  drawPattern(0, 0, width/2, 2);
  drawCircle(0, 0, width, 2);// change last argument to 1 for more detail
  theta = map(mouseX,0,width,0,PI/2);
  translate(width/2, height);
  //stroke(0);
  branch(75);
}

void drawPattern(float x, float y, float squareSize, float minSize) {
  stroke(0,0,0);
  strokeWeight(1);
  fill(random(1, 255), random(1, 255), random(1, 255));
  rect(x, y, squareSize, squareSize);
  rect(x+squareSize, y, squareSize, squareSize);
  rect(x, y+squareSize, squareSize, squareSize);
  if (squareSize > minSize) {
    drawPattern(x, y, squareSize/2, minSize);
    drawPattern(x+squareSize, y, squareSize/2, minSize);
    drawPattern(x, y+squareSize, squareSize/2, minSize);
  }
}

void drawCircle(float x, float y, float squareSize, float minSize) {
  stroke(0,0,0);
  strokeWeight(1);
  fill(random(1, 255), random(1, 255), random(1, 255));
  ellipse(x, y, squareSize, squareSize);
  ellipse(x+squareSize, y, squareSize, squareSize);
  ellipse(x, y+squareSize, squareSize, squareSize);
  if (squareSize > minSize) {
    drawCircle(x, y, squareSize/2, minSize);
    drawCircle(x+squareSize, y, squareSize/2, minSize);
    drawCircle(x, y+squareSize, squareSize/2, minSize);
  }
}

void branch(float len) {

  float theta = random(0,PI/3);
  stroke(random(0,255), random(0,255), random(0,255));
  strokeWeight(10);
 
  line(0, 0, 0, -len);
  translate(0, -len);
  len *= 0.75;
  if (len > 2) {
    pushMatrix();
    rotate(theta);
    branch(len);
    popMatrix();
    pushMatrix();
    rotate(-theta);
    branch(len);
    popMatrix();
  }
}