In Spirou example you chop time at 33.333 ms, but your update goes not exactly at this time , intervals can be
28 36 33 34 29 38 ... but average will be = 33.333 ms and usualy there is no need to pass parameter to update function Update( 33333ULL ) if its your own engine;
To render smoothly you need calc interpolation variable alpha=0.0..1.0 to know how far you are to next update.
So engine gives alpha, renderer draws according to this alpha.

In Spirou example you chop time at 33.333 ms, but your update goes not exactly at this time , intervals can be
28 36 33 34 29 38 ... but average will be = 33.333 ms
To render smoothly you need calc interpolation variable alpha=0.0..1.0 to know how far you are to next update.
So engine gives alpha, renderer draws according to this alpha.

In Spirou example you chop time at 33.333 ms, but your update goes not exactly at this time , intervals can be
28 36 33 34 29 38 ... but average will be = 33.333 ms
To render smoothly you need calc interpolation variable alpha=0.0..1.0 to know how far you are to next update.
So engine gives alpha, renderer draws according this alpha.