# [Tutorial] Simple WebMap

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Posted (edited)

Hello everyone! In this tutorial I will try to show you how to create a Web map of your server.

Stage 0 - Some usefull stuff

We need to walk around GTA map, so lets create a resource to make it easier:

```
mp.vehicles.new(veh, player.position)
}) // Create a vehicle
mp.events.addCommand('tp', (player, _, x, y, z)=> {
player.giveWeapon(0xFBAB5776, 2) // Parachute, you need this, trust me
player.position = new mp.Vector3(parseInt(x), parseInt(y), parseInt(z))
}) // Teleport a player
console.log(player.position.x + ' ' + player.position.y + ' ' + player.position.z)
}) // Get player coords at write it to console```

Stage 1 - Frontend

Step 1:  Get a map image, you can find some good images here:

I will use 4096*4096 satellite map.

Step 2: Create a html file for our map:

```<img src='http://blog.damonpollard.com/wp-content/uploads/2013/09/GTAV_SATELLITE_4096x4096.png' style="position: absolute">
<canvas id='map' style='height: 4096px; width: 4096px; position: absolute; z-index: 9999'>```

This code adds a picture and then puts a canvas over it, so we can draw above our map.

Step 3: Lets make some calculations

0) First of all, install commands from Stage 0 to your gamemode and then connect to your server.

1) Open your map picture with Paint

2) Determine zero point

Teleport to (0, 0, 72) position and determine this location at your map inside paint (put pointer on it), write down coordinates

3) Determine map scale

Choose two points at map. I will use the most northen island and LS Aiport

Write down 'paint' coordinates for both.

It is (1889, 232) (1570, 3939) for me (if you use map with another size, you will get different numbers).

Calculate range between this coords, it is 3720.7002 for me.

Then go to GTA and walk to both points

Write /pos to output your position to console

34.01333999633789 7689.458984375 2.8789443969726562 - northen island

-933.9918823242188 -3570.4599609375 14.037487030029297 - airport corner

Then calculate distance between this points only with x and y axis.

Result: 11301.451622046046 (meters)

Now lets finally get map scale: for me it is 11301.451622046046 (meters) / 3720.7 (pixels) = 3.037861303705727 (meters per pixel)

4) Determine axises

Red is world coords, green - picture/html coords

First of all, we need a function that converts world coordinates to picture coordinates.

```const ZeroX = 1903
const ZeroY = 2690
const Scale = 3.037861303705727
function getPictureCoords(x, y) {
x = x/Scale
y = y/Scale
return {x: ZeroX + x , y: ZeroY - y} // Invert Y-axis
}```

You can test it by teleporting to random coords and then finding that place in paint

Now it's time to start drawing.

`const ctx = document.getElementById('map').getContext('2d')`

Lets make a function that draws a player marker (red circle and a name above it)

```function drawPlayerMarker(x, y, name) {
newCoords = getPictureCoords(x, y)
x = newCoords.x
y = newCoords.y
ctx.fillStyle = 'red'
ctx.beginPath()
ctx.arc(x, y, 5, 0, 2 * Math.PI)
ctx.fill()
ctx.font = "25px Arial";
ctx.fillText(name, x - 15, y - 15)
}```

Lets test it!

It works!

Stage 2 - Backend

We will use socket.io to communicate between browser and server.

Step 0: Install express and socket.io packages.

Run windows command line -> change directory to your /server-files directory -> run npm install express npm install socket.io

Step 1: Create express app

```//load map.html and socket.io
var fs = require('fs')
const port = 3000
//create app
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
//listen 3000 port
http.listen(3000, function(){
console.log('webMap is active at 3000 port!');
});
//send map.html and socket.io to every client
app.get('/', function (req, res) {
res.send(mapHTML);
});
app.get('/socket.io.js', function (req, res) {
res.send(socketIO);
})```

Put your map.html file to /server-files/webmap folder

Then go to \server-files\node_modules\socket.io-client\dist, find socket.io.js file and put it to server-files/webmap folder

Step 2: Prepare and send data to client

```function prepareAndSendPlayersData() {
var toSend = []
mp.players.forEach((player)=> {
toSend.push({
x: player.position.x,
y: player.position.y,
name: player.name
})
})
sendPlayersData(toSend)
}

function sendPlayersData(data) {
io.sockets.emit('playersData', data) // Send our data to every client
}```

Step 3: Create interval

`setInterval(prepareAndSendPlayersData, 200) // Update every 200 ms`

Stage 3 - Receiving data on client

`<script src="/socket.io.js"></script>`

Step 2: Add variable and event to handle data

```var playersData = []

var socket = io('localhost:3000') // Your server ip here

socket.on('playersData', (data) => {
playersData = data
redraw()
})```

Step 3: Redraw map with new data

```function redraw() {
ctx.clearRect(0, 0, 4096, 4096);
playersData.forEach((player)=> {
drawPlayerMarker(player.x, player.y, player.name)
})```

Thats all! You can run your server, then open browser and go to youserverip:3000 and test it.

map.js (server package)

Скрытый текст
```//load map.html
var fs = require('fs')

//create app
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
//send map.html to every client
app.get('/', function (req, res) {
res.send(mapHTML);
});
app.get('/socket.io.js', function (req, res) {
res.send(socketIO);
})

http.listen(3000, function(){
console.log('listening on *:3000');
});

function prepareAndSendPlayersData() {
var toSend = []
mp.players.forEach((player)=> {
toSend.push({
x: player.position.x,
y: player.position.y,
name: player.name
})
})
sendPlayersData(toSend)
}

function sendPlayersData(data) {
io.sockets.emit('playersData', data) // Send our data to every client
}

setInterval(prepareAndSendPlayersData, 200)```

map.html (put it to server-files/webmap folder)

Скрытый текст
```<img src='http://blog.damonpollard.com/wp-content/uploads/2013/09/GTAV_SATELLITE_4096x4096.png' style="position: absolute">
<canvas height='4096', width='4096', id='map' style='height: 4096px; width: 4096px; position: absolute; z-index: 9999'>
<script src="/socket.io.js"></script>
<script>
const ZeroX = 1903
const ZeroY = 2690
const Scale = 3.037861303705727
function getPictureCoords(x, y) {
x = x/Scale
y = y/Scale
return {x: ZeroX + x , y: ZeroY - y} // Invert Y-axis
}

const ctx = document.getElementById('map').getContext('2d')
ctx.fillStyle = 'red'

function drawPlayerMarker(x, y, name) {
newCoords = getPictureCoords(x, y)
x = newCoords.x
y = newCoords.y
ctx.beginPath()
ctx.arc(x, y, 5, 0, 2 * Math.PI)
ctx.fill()
ctx.font = "25px Arial";
ctx.fillText(name, x - 15, y - 15)
}

var playersData = []

var socket = io('localhost:3000')

socket.on('playersData', (data) => {
playersData = data
redraw()
})

function redraw() {
ctx.clearRect(0, 0, 4096, 4096);
playersData.forEach((player)=> {
drawPlayerMarker(player.x, player.y, player.name)
})
}
</script>```

This tutorial will be continued

Have a good day!

Edited by Hanvod
• 4