3d problem with a simple title game

Processing Libraries
14

here one piece moves

float factor1=80.0; // dist between boxes
float offsety=0;

void setup() {
  size( 800, 800, P3D );

  stroke(111);  // gray 
  fill(255, 2, 2); // red
} // setup

void draw() {
  background(0);
  lights();

  translate(width/2-factor1, height/2, 0); 

  int i=0; 

  for (int x=0; x<3; x++) {
    for (int y=0; y<3; y++) {

      if (i==3) {

        pushMatrix(); 
        translate(x*factor1, 
          y*factor1+offsety, 
          1*factor1);
        box(70);  // size of 40 (width, height and depth) 
        popMatrix();
      } else
      {
        pushMatrix(); 
        translate(x*factor1, 
          y*factor1, 
          1*factor1);
        box(70);  // size of 40 (width, height and depth) 
        popMatrix();
      }
      i++;
    }
  }
  offsety-=0.2;
} // draw