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| function toRad(deg) { | |
| return deg * (Math.PI / 180); | |
| } | |
| function toDeg(rad) { | |
| return rad / (Math.PI / 180); | |
| } | |
| const EARTH_R = 6378.1; | |
| function getNewCoords(initLoc, distance, bearing) { | |
| const bearingR = toRad(bearing); | |
| const initCoords = {lat: toRad(initLoc.lat), lng: toRad(initLoc.lng)}; | |
| const newLat = Math.asin(Math.sin(initCoords.lat) * Math.cos(distance/EARTH_R) + | |
| Math.cos(initCoords.lat) * Math.sin(distance/EARTH_R) * Math.cos(bearingR)); | |
| const newLng = initCoords.lng + Math.atan2(Math.sin(bearingR) * Math.sin(distance/EARTH_R) * | |
| Math.cos(initCoords.lat), Math.cos(distance/EARTH_R) - Math.sin(initCoords.lat) * Math.sin(newLat)); | |
| return {lat: toDeg(newLat), lng: toDeg(newLng)}; | |
| } | |
| function generateLocationSteps(initialLocation, stepCount=12) { | |
| const NORTH = 0, | |
| EAST = 90, | |
| SOUTH = 180, | |
| WEST = 270; | |
| const pulseRadius = 0.07; // km - radius of players heartbeat is 70m | |
| const xdist = Math.sqrt(3)*pulseRadius; // dist between column centers | |
| const ydist = 3*(pulseRadius/2); // dist between row centers | |
| let locations = [initialLocation]; | |
| let ring = 1; | |
| let loc = initialLocation; | |
| while (ring < stepCount) { | |
| loc = getNewCoords(loc, ydist, NORTH); | |
| loc = getNewCoords(loc, xdist/2, WEST); | |
| for (let direction=0; direction < 6; direction++) { | |
| for (let i=0; i < ring ; i++) { | |
| if (direction === 0) { // RIGHT | |
| loc = getNewCoords(loc, xdist, EAST) | |
| } | |
| if (direction === 1) { // DOWN + RIGHT | |
| loc = getNewCoords(loc, ydist, SOUTH) | |
| loc = getNewCoords(loc, xdist/2, EAST) | |
| } | |
| if (direction === 2) { // DOWN + LEFT | |
| loc = getNewCoords(loc, ydist, SOUTH) | |
| loc = getNewCoords(loc, xdist/2, WEST) | |
| } | |
| if (direction === 3) { // LEFT | |
| loc = getNewCoords(loc, xdist, WEST) | |
| } | |
| if (direction === 4) { // UP + LEFT | |
| loc = getNewCoords(loc, ydist, NORTH) | |
| loc = getNewCoords(loc, xdist/2, WEST) | |
| } | |
| if (direction === 5) { // UP + RIGHT | |
| loc = getNewCoords(loc, ydist, NORTH) | |
| loc = getNewCoords(loc, xdist/2, EAST) | |
| } | |
| locations.push(loc); | |
| } | |
| } | |
| ring = ring + 1; | |
| } | |
| return locations; | |
| } |
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example usage: