NAME
node-morton - Calculates morton numbers and Z-order codes for spatial indexing.
USAGE
Install with npm install morton.
var morton = require('morton');
morton(32, 436); // => 167456
morton.code(1, 0, 1); // => 140737488355328
morton.code(2, 0, 2); // => 140737488355328
morton.code(3, 0, 4); // => 140737488355328
morton.code(4, 0, 8); // => 140737488355328
morton.range(1, 0, 0); // => [ 0, 70368744177663 ]
morton.range(1, 1, 0); // => [ 70368744177664, 140737488355327 ]
morton.range(1, 0, 1); // => [ 140737488355328, 211106232532991 ]
morton.range(1, 1, 1); // => [ 211106232532992, 281474976710655 ]
Note: input numbers must be smaller than 2^24 (16777216). Since the resulting output has twice as many bits, you'll get back numbers that are up to 2^48 (281474976710656). JavaScript can still represent these numbers without losing precision, however, you can't use bitwise operators on these numbers if your input numbers are potentially bigger than 2^15 (32768) because JavaScript only supports bitwise operators on 32 bit signed integers.
morton.code(z, x, y) returns a 48-bit Z-order code.
morton.range(z, x, y) will return an array of the lower and upper bound of the Z-order rectangle. See also Z-order curves in Wikipedia.
[x, y] = morton.reverse(c) reverses c = morton(x, y).
[x, y] = morton.decode(z, c) reverses c = morton.code(z, x, y).
TESTS
expresso is required to run unit tests.
npm install expresso
expresso
CONTRIBUTORS
ACKNOWLEDGEMENTS
Thanks to Sean Eron Anderson for his Bit Twiddling Hacks page.
LICENSE
node-morton is BSD licensed.