int n = 5;
float[] px = new float[n];
float[] py = new float[n];
void setup(){
  float angle = 2 * PI / n; //divide the circle in n sect
  for(int i =0; i< n; i++){
    px[i] = 50. + 30. * sin(angle*i);
    py[i] = 50. + 30. * cos(angle*i);
  }
  rectMode(CENTER);
}
void draw (){
  background(200);
  beginShape(POLYGON);
  for(int i = 0; i < n; i++)
    vertex(px[i],py[i]);
  endShape(CLOSE);
  for(int i=0; i<n; i++){
    if(dist(mouseX,mouseY,px[i],py[i])<20)
      stroke(255,0,0);
    else
      stroke(0,0,0);
    rect(px[i],py[i],5,5);
  }
}
void mouseDragged(){
  for(int i=0; i<n; i++)
    if(dist(mouseX,mouseY,px[i],py[i])<20){
    px[i] += (mouseX-pmouseX); //push only
    py[i] += (mouseY-pmouseY);
    px[i] = constrain(px[i],5,width-5);
    py[i] = constrain(py[i],5,height-5);
  }
}