void tree(float x1, float y1, float x2, float y2, int depth) {

  if (depth <= 0) {
    return;
  }

  float dx = (x2 - x1);
  float dy = (y1 - y2);

  float x3 = (x2 - dy);
  float y3 = (y2 - dx);
  float x4 = (x1 - dy);
  float y4 = (y1 - dx);
  float x5 = (x4 + 0.5*(dx - dy));
  float y5 = (y4 - 0.5*(dx + dy));

  // square
  beginShape();
  fill(0.0, 255.0/depth, 0.0);
  vertex(x1, y1);
  vertex(x2, y2);
  vertex(x3, y3);
  vertex(x4, y4);
  vertex(x1, y1);
  endShape();

  // triangle
  beginShape();
  fill(0.0, 255.0/depth, 0.0);
  vertex(x3, y3);
  vertex(x4, y4);
  vertex(x5, y5);
  vertex(x3, y3);
  endShape();

  tree(x4, y4, x5, y5, depth-1);
  tree(x5, y5, x3, y3, depth-1);
}

void setup() {
  size(1920, 1080);
  background(255);
  stroke(0, 255, 0);
  tree(width/2.3, height, width/1.8, height, 10);
}