Ok my head just exploded.DivotMaker wrote: To summarize:
One foot downhill putt of 25' according to your lie indicator on the HUD.
Putting marker at the cup indicates 25 feet away, 10 inches below the ball.
Assuming a straight putt, move the marker back until the sum total of distance and inches downhill add up to 15 feet (25 foot putt minus 10 inches downhill).
If the marker is at 15 feet and you still have 5" of downhill, you need to keep bringing the marker to you until the sum total of distance and amount downhill equals 15.
If the slope of the green PAST the cup continues to be steep, you may consider taking a couple feet more of distance off the marker or hitting your putt lighter to compensate. The end goal in a downhill putt is if you don't make it, you at least have a reasonable chance to make the come backer.
Uphill putts are simila

Lets see if I get this because I feel like I am missing something.
I have a 30 foot put and the hud says downhill 1 foot. I assume by hud you mean over the hole.
I move the aiming marker to the hole and it says downhill 10 inches,
I take 30 and subtract 10 and move the aiming marker to 20 feet from me, ie 10 feet les that the hole. Now it says downhill 5 inches.
I take 20-5 an move marker back to 15 feet.
I continue to do this until when? there is no break left?
When I get to that point what exactly is that telling me?
I'm totally missing something in your explanation.