Quick and Easy Sprite –Victorian Rush Hour - Cocos2d-x by Example Beginner's Guide - page 207

case kBlock3:
this->setColor(Color3B(100,100,100));
break;
case kBlock4:
this->setColor(Color3B(50,50,50));
break;
}
this->setVisible(true);
}
kBlockGap means there is no building, just a gap the _player object must
jump. We make the block invisible in that case and return from the function. So
again, gaps are actually types of blocks in our logic.
In this test version, the different types of buildings are represented with different colors.
Later we'll use different textures.