Unfortunately, I cannot see any way to get the display of the print in the same place each time.
Due to the assumptions made by the interpreter, a move of 100mm say, will always result in the next print being displayed at a point 100mm from the first one.
The concept that the X axis has essentially not moved, rather the workpiece has moved across the X plane, is not one that is catered for.
If it was displayed, it would display in exactly the same place that there was already a trace from the last print, so the usefulness might be lessened anyway.
The only software solution would be to automatically centre the origin point within the screen whenever it is reset.
OpenGL programming is not my forte and such an implementation would be wrong for every other conventional machine, where the origin point is displayed within the context of a finite work envelope.
If your film was on a powered reel, moving across an essentially static table, I could envisage setups that moved it without using the X axis and thus would produce the plot you desire.
( advancing it outside the knowledge of the plot interpreter through an M code activated motor movement say)
The main thing is the code will produce the repetition you require hopefully, you may just have to live with the plot.
regards
