// Add an object to look at. the_object = the_satellite(); LINK(the_scene, PLUS, rotate(Z, X, 720*worldtime, rotate(X, Y, 360*worldtime, bind(the_object))));
The satellite rotations demonstrate an animation technique called looping . Looping is when a number of frames can be played repeatedly without the animation breaking between the last frame and the first frame. To achieve this with n frames the nth frame must be the same as frame 0.
The satellite code is a 1 sec or 25 frame loop. A rotation of 360 degrees places the object back at the starting position. Both the satellite rotations are 0 degrees when worldtime = 0 and a multiple of 360 degrees when worldtime = 1.0. This makes frame 25 and frame 0 the same. (Only frames 0 to 24 should be included in the animation).
Figure 18 shows six frames from the one second animation.
Figure 18: Satellite Animation