(The drawing method of character titles and blood bars is very simple, but the problem of our demand management is to find suitable coordinates in the 3D world. Since the character in the 3D world can move, it moves in the 3D world, not in the 2D plane, but we need to convert the 3D character coordinates into the coordinates in the 2D plane, and then find the 2D coordinates of the head of the character in the screen, and finally use the GUI to draw the title and blood bar.)