Thursday, 25 January 2018

Node JS Football / Soccer Simulation Engine Module

Football Simulation Engine - Node Module

As previously mentioned in my blog HERE, I had been looking to design and build a football manager game, with the main purpose being to improve my JavaScript (JS) and node (Node JS) skills. I soon found there were no existing node package modules (npm) that could provide a simulated match result.

I posted on a few sites to try and see if anyone had done this before - there’s no point repeating work is there? After finding nothing specific that matched my purpose I went on ahead and built my prototypes which consisted of two random numbers and a little use of player skill to create results (see previous blog), but it didn’t really fit the bill for a football manager games back end as it didn’t take other factors into consideration.

So, I went ahead and built my own, and as of today it is now available on the npm website HERE or run 
          npm install footballsimulationengine

How does it work?
Great question, glad you asked. Basically, you provide it with two JSON strings, each its own team and requiring a specific set of JSON objects. This includes team name, players, player positions, skills and each players starting position.
Example:
{
  "name": "Team1",
  "players": [{
      "name": "Player",
      "position": "GK",
      "rating": "99",
      "skill": {
        "passing": "99",
        "shooting": "99",
        "tackling": "99",
        "saving": "99",
        "agility": "99",
        "strength": "99",
        "penalty_taking": "99",
        "jumping": "300"
      },
      "startPOS": [60,0],
      "injured": false
    }...],
  "manager": "Aiden"
}

Key things to remember:
·      Each team MUST have 11 players
·      The code currently does not check these parameters, so the skills SHOULD be between 1 and 100.
·      Except for “jumping” which is intended to be the maximum jump height of the player in centimetres.
·      Start Position should between you pitch Sizes Width and half of the pitch length. The code deals with switching their start position side. E.g if my pitch size is [120, 600], “startPOS” SHOULD BE [0-120, 0 - 300].

The other thing we will need to start a game/match is pitch size, which is shown in [width, height] where the pitch is intended to be taller than it is wide, like below.

PIC

Example Pitch JSON:
{
            "pitchWidth": 120,
            "pitchHeight": 600
}

We feed these three JSONs into the initiate function like so:

Example:
initiateGame(team1, team2, pitch).then(function(matchDetails){
  console.log(matchDetails);
}).catch(function(error){
  console.error("Error: ", error);
})

what we get back is a super larger JSON with both teams, their originPOS (so we can get them back to their original position), relativePOS (so we know where they’re heading towards), and a whole bunch of match details such as the score, number of shots and importantly, where the ball is, ball direction.

The main idea is that the game runs in iterations this allows the client using the simulation engine to change players throughout the game, set up the game in certain positions.

Playing iterations is then as simple as running that big old outputted JSON back into a play iteration function which in turn, gives an updated big old output JSON.

Example:
playIteration(matchDetails).then(function (matchDetails) {
  console.log(matchDetails);
}).catch(function(error){
  console.error("Error: ", error);
}

Example Output:
{ kickOffTeam:
   { name: 'Team1',
     players:
      [ [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object] ],
     manager: 'Aiden'
     intent: 'defend' },
  secondTeam:
   { name: 'Team2',
     players:
      [ [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object] ],
     manager: 'Joe',
     intent: 'attack' },
  pitchSize: [ 120, 600 ],
  ball:
   { position: [ 76, 314 ],
     withPlayer: true,
     Player: 'Joe Bloggs',
     withTeam: 'Team2',
     direction: 'south' },
  half: 1,
  kickOffTeamStatistics:
   { goals: 0,
     shots: 0,
     corners: 0,
     freekicks: 0,
     penalties: 0,
     fouls: 0 },
  secondTeamStatistics:
   { goals: 0,
     shots: 0,
     corners: 0,
     freekicks: 0,
     penalties: 0,
     fouls: 0 },
  iterationLog:
   [ 'Closest Player to ball: Aiden Gallagher',
     'Closest Player to ball: Joe Bloggs' ] }

An important feature here is the “iterationLog” which gives an overview of what has happened during that iteration. i.e. someone has passed the ball, someone has taken a shot, scored, freekick awarded, penalty taken, a throwin given and taken.

Finally, the last function that can be played is switch sides of the teams that are playing, i.e. after half time or if running into extra time.

Example:
startSecondHalf(matchDetails).then(function (matchDetails) {
  console.log(matchDetails);
}).catch(function(error){
  console.error("Error: ", error);
}

TL;DR / Overview:
·      Three function; initiateGame - needs two team JSONs and a Pitch Details JSON, playIteration - takes the output from initiate game and updates one movement of each player, startSecondHalf - switches the sides the players are on.
·      All three functions are return promises
·      JSON isn’t checked so make sure you’ve got it right
·      Recommended match length is 10,000 iterations.

If you’d like help setting up, have some general questions please feel free to comment below and I’ll get back to you ASAP.

Improvements:
This code is setup on a public Github which you can find HERE and I’m hoping people who use the module (if anyone) will help me improve it! You can raise issues HERE but otherwise please get in touch by email: aiden.g@live.co.uk

Visual Example:
For those who want to see, here is a youtube video of the game being used in an example I have set up. Feel free to get in touch and I can send you the "manager" setup and some instructions. 


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