void setup() {
  size(200,200);
  background(255);
  person(50, 150, 30);
  person(100, 180, 20);
  person(150, 150, 30);
}

/*
  Draw a person centered above (x,y) having width w.
  The rest of the size is proportional to the width,
  but with visual stroke weight 1 at any scale.
*/
void person(int x, int y, int w) {
  pushMatrix();
  pushStyle();
  translate(x,y);
  scale(w/10.0);
  strokeWeight(10.0/w);
  line(-5, 0, 0, -10);         // left leg
  line(5, 0, 0, -10);          // right leg
  line(0, -10, 0, -20);        // trunk
  line(0, -15, -5, -20);       // left arm
  line(0, -15, 5, -20);        // right arm
  ellipse(0, -25, 10, 10);     // head
  popMatrix();
  popStyle();
}