finger

int frms = 500;
float angle;

void setup() {
  size(500, 500);
  rectMode(CENTER);
}

void draw() {
  background(255);
  float sz = 300;
  translate(width/2, height/2);
  rect(0, 0, sz, sz);
  float x = cos(angle)*sz;
  println(x);
  float px = constrain(x, -sz/2, sz/2);
  float y = sin(angle)*sz;
  float py = constrain(y, -sz/2, sz/2);
  line(0, 0, px, py);
  angle += TWO_PI/frms;
}