Merge pull request #403 from Mygod/cyrb53-offset

Use pseudorandom offsets

Author: TurtIeSocks

src/components/tiles/Pokemon.jsx

@@ -1,3 +1,4 @@
+/* eslint-disable no-bitwise */
 import React, { memo, useRef, useState } from 'react'
 import { Marker, Popup, Circle } from 'react-leaflet'
 
@@ -16,12 +17,28 @@ const operator = {
   '>=': (a, b) => a >= b,
 }
 
-const getOffset = (coords, type) => coords.map(coord => {
-  let offset = Math.random() * 0.0002 - 0.0001
+const cyrb53 = (str, seed = 0) => {
+  let h1 = 0xdeadbeef ^ seed
+  let h2 = 0x41c6ce57 ^ seed
+  for (let i = 0, ch; i < str.length; i += 1) {
+    ch = str.charCodeAt(i)
+    h1 = Math.imul(h1 ^ ch, 2654435761)
+    h2 = Math.imul(h2 ^ ch, 1597334677)
+  }
+  h1 = Math.imul(h1 ^ (h1 >>> 16), 2246822507) ^ Math.imul(h2 ^ (h2 >>> 13), 3266489909)
+  h2 = Math.imul(h2 ^ (h2 >>> 16), 2246822507) ^ Math.imul(h1 ^ (h1 >>> 13), 3266489909)
+  return [h1, h2]
+}
+
+const getOffset = (coords, type, seed) => {
   const offOffset = type === 'nearby_cell' ? 0.0002 : 0.00015
-  offset += offset >= 0 ? -offOffset : offOffset
-  return (coord + offset)
-})
+  const rand = cyrb53(seed)
+  return [0, 1].map(i => {
+    let offset = rand[i] * (0.0002 / 4294967296) - 0.0001
+    offset += offset >= 0 ? -offOffset : offOffset
+    return (coords[i] + offset)
+  })
+}
 
 const getGlowStatus = (item, userSettings, staticUserSettings) => {
   let glowCount = 0
@@ -58,7 +75,7 @@ const PokemonTile = ({
   const weatherCheck = item.weather && userSettings.weatherIndicator
 
   const finalLocation = item.seen_type?.startsWith('nearby')
-    ? getOffset([item.lat, item.lon], item.seen_type)
+    ? getOffset([item.lat, item.lon], item.seen_type, item.id)
     : [item.lat, item.lon]
 
   useForcePopup(item.id, markerRef, params, setParams, done)