The multiplayer Game Jam
@OpherV
Fullstack2gether 2017
Can we make this experience
easier? faster?
realtime multiplayer game running in the browser
@opherv
Hi! I'm Opher
I'm a creative developer at Eko
http://lance.gg
Lance is:
@opherv
Multiplayer server + client library
Written entirely in JavaScript
Open source and free to use
Makes multiplayer games on the web easy(ish) and fun!
anatomy of a game
@opherv
while (true)
{
processInput();
updateGameState();
render();
}
Input
0
1
2
3
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5
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7
render
game step
8
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@opherv
peer-to-peer
Why do you even need a server?
Because your players suck
@opherv
if cheating can happen,
it will happen
authoritative server
@opherv
authoritative server
Run game world
Receive input request
Validate input
Broadcast game state
13,759 km
299,792,458 m / s
Speed of Light
45 milliseconds
Tel Aviv -> Melbourne
Round Trip Time (RTT) > 90ms
@opherv
Tel Aviv
Melbourne
Request - 45ms
Reply - 45ms
LAG
Syncing the game world
Game Loop
Render Loop
@opherv
Broadcast Loop
Input
0
1
2
3
4
5
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7
Broadcast
game step
8
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15
Server view
Option 1
client step N
X: 200
client step M
X: 50
Interpolation
30
31
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34
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39
26
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The client is in the past
Real Time Strategy *
Role Playing Games
"client side prediction"
Player presses "up"
Running the same game code,
both on the server and the client
@opherv
The client is in the past
but also... kinda in the future
"bending"
Physics based games
First person shooters
But what about...
Option 2: Extrapolation
30
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39
30
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Input
game state
extrapolated
steps
Interpolation
Faster, less precise
Smoother movement at the cost of delay
Extrapolation
Requires heavier simulation
Essential for physics-based games
@opherv
All must implement:
Client side prediction
Bending
@opherv
@opherv
@opherv
@opherv
more info: http://lance.gg
@opherv
Free Stickers!
follow me @OpherV
Lets start!
@OpherV
opherv.com