// draw a red point every 1/8th of a circle, with function
void setup() {
  size(600, 600);
  noStroke();
  fill(255, 0, 0);
  
  drawCircle(width/2, height/2, 50);
}

void drawCircle(int centerx, int centery, int radius) {
  int steps = 8;

  float angle = 2*PI/steps;
  for (int i=0; i<steps; i++) {
    float x = cos(angle*i)*radius + centerx;
    float y = sin(angle*i)*radius + centery; 

    ellipse(x, y, 10, 10);
  }
}