public void keyPressed() {
   if (key == '-') {
     sceneZoom -= sceneStep;
   }
   if (key == '+') {
     sceneZoom += sceneStep;
   }
   if (key == ' ' || key == 'q') {
     System.out.println("SAFE!!!");
     controlGroup.safeDrone();
     markerControlled.setInAir(false);
   }
   if (key == 's') {
     controlGroup.stop();
   }
   if (key == 't') {
     controlGroup.takeOff();
     markerControlled.setInAir(true);
   }
 }
 public void draw() {
   background(0);
   lights();
   if (commandsRight != null) commandsRight.display();
   if (videoRight != null) videoRight.display();
   if (commandsLeft != null) commandsLeft.display();
   if (videoLeft != null) videoLeft.display();
   if (markerControlled != null) markerControlled.display();
   translate(width / 2, height / 2, sceneZoom);
   rotateX(sceneRotX);
   rotateY(sceneRotY);
   rotateZ(sceneRotZ);
   if (controller != null) controller.display();
 }