grid-fns v0.0.1

grid-fns

Functions for working with Grids

install

npm install grid-fns

functions

• calc_cell_size
• prepare_snap
• prepare_unsnap

usage

calc_cell_size

import calc_cell_size from "grid-fns/calc_cell_size.js"

calc_cell_size([-180, -90, 180, 90], [1024, 768])
[0.3515625, 0.234375] // [cell width, cell height]

prepare_snap

Snap a grid point to a cell and return the cell's id.

import prepare_snap from "grid-fns/prepare_snap.js"

const snap = prepare_snap({ bbox: [-180, -90, 180, 90], size: [1024, 768] })

snap(-180, 90) // top-left corner
0

snap(180, 90) // top-right corner
1024

snap(179.999999999, -89.9999999999) // bottom-right cell
786431

prepare_unsnap

Creates a function that returns a coordinate for a given cell id

const unsnap = prepare_unsnap({ bbox: [-180, -90, 180, 90], size: [1024, 768] })
unsnap(0);
[-179.82421875, 89.8828125] // center of top-left cell

unsnap(1024)
[-179.82421875, 89.6484375] // center of top-right cell