This ellipse thing is really pissing me off. After lots of searching I thought I’d found the exact equation, except it does’ work. So went back to my original system, this uses ray casts, well line intersections. It’s pixel perfect in the major axis and I can also work out the midpoint, the thing I’m stuck with now is the minor axis radius. I think I’ve sort of worked it out. You need to calculate the new ‘height’ from the midpoint. So if you’ve moved five meters to the right and you were one hundred meters up, then just using pythagorus you can calc the new distance, then I think it’s just taking the tan of the alpha and multiplying by that. That should give the circle radius if it was going that distance. Hopefully that’s the last part of the puzzle.
Now to drink heavily.