マウスの近くの球が近づく

/**
* Pop Up Surface
*
* @author aa_debdeb
* @date 2015/11/26
*/

void setup(){
  size(500, 500, P3D);
  smooth();
  sphereDetail(10);
}

void draw(){
  background(0);
  noStroke();
  fill(255);
  lights();
  for(int x = -100; x < width + 100; x += 20){
    for(int y = -100; y < height + 100; y += 20){
      pushMatrix();
      float d = sqrt(sq(x - mouseX) +  sq(y - mouseY));
      float z = -100;
      if(d < 200){
        z += 0.5 * sqrt(sq(200) - sq(d));
      }
      translate(x, y, z);
      sphere(5);
      popMatrix();
    }
  }
}