hash function providing unique uint from an integer coordinate pair

Question

The problem in general: I have a big 2d point space, sparsely populated with dots. Think of it as a big white canvas sprinkled with black dots. I have to it

Answer 1

the Fibonacci hash works very well for integer pairs

multiplier 0x9E3779B9

other word sizes 1/phi = (sqrt(5)-1)/2 * 2^w round to odd

a1 + a2*multiplier

this will give very different values for close together pairs

I do not know about the result with all pairs