For a rectangular selection, you can use sort_by! to sort the array in-place by y first (top to bottom) and x second (left to right):
ary = [[60, 60], [10, 10], [10, 60], [60, 10]]
ary.sort_by! { |x, y| [y, x] }
#=> [[10, 10], [60, 10], [10, 60], [60, 60]]
or: (because [y, x] is the reverse of [x, y])
ary.sort_by!(&:reverse)
#=> [[10, 10], [60, 10], [10, 60], [60, 60]]
This works, because arrays are sorted in an element-wise manner, i.e. it will sort all elements by y and elements with identical y value by x. (see Array#<=>)
For a non-rectangular selection like in your example, it's more tricky because the y coordinates are not pairwise equal and the above approach won't work. Let's switch the x-values for the bottom coordinates to make that problem more obvious:
ary = [[810, 266], [236, 236], [814, 800], [230, 820]]
ary.sort_by!(&:reverse)
#=> [[236, 236], [810, 266], [814, 800], [230, 820]]
# ^^^ ^^^
In the above result, the bottom left coordinate comes after the bottom right coordinate.
Assuming that your coordinates are roughly rectangular, you could first sort by y only (which is the last value) to get the top 2 coordinates first and the bottom 2 coordinates last:
ary.sort_by!(&:last)
#=> [[236, 236], [810, 266], [814, 800], [230, 820]]
You could then sort each of the top-two and bottom-two separately by x (which is the first value):
ary[0..1] = ary[0..1].sort_by(&:first)
ary[2..3] = ary[2..3].sort_by(&:first)
ary
#=> [[236, 236], [810, 266], [230, 820], [814, 800]]
Note that [230, 820] goes before [814, 800] now despite having a larger y-value.
Special cases like kite or dart shaped selections might require different sorting order.
