// Constrain 
// by REAS <http://reas.com> 

float mx; 
float my; 
float delay = 40.0; 
float esize = 25.0; 
int box = 30; 
 
void setup() 
{ 
  size(200, 200); 
  noStroke(); 
  smooth(); 
  ellipseMode(CENTER_RADIUS);  
} 
 
void draw() 
{ 
  background(51); 
  
  if(abs(mouseX - mx) > 0.1) { 
    mx = mx + (mouseX - mx)/delay; 
  } 
  if(abs(mouseY - my) > 0.1) { 
    my = my + (mouseY- my)/delay; 
  } 
  
  float distance = esize * 2; 
  mx = constrain(mx, box+distance, width-box-distance); 
  my = constrain(my, box+distance, height-box-distance); 
  fill(76); 
  rect(box+esize, box+esize, box*3, box*3); 
  fill(255);  
  ellipse(mx, my, esize, esize); 
}