additional animation variables
// additional animation variables
#declare X=clock_delta; // clock step between frames
#declare X=initial_clock; // clock value of first rendered frame (+KIn.n)
#declare X=final_clock; // clock value of last rendered frame (+KFn.n)
#declare X=initial_frame; // initial frame number (+KFIn).
#declare X=final_frame; // final frame number (+KFIn).
#declare X=clock_on; // true if scene is rendered as an animation