Emanuele Feronato

var game;
var gridWidth = 40;
var gridHeight = 40;
var tileSize = 16;
var sightRadius = 10;
var wallRatio = 3;
var maze = [];

window.onload = function() {	
	game = new Phaser.Game(640, 640, Phaser.AUTO, "");
     game.state.add("PlayGame", playGame);
     game.state.start("PlayGame");
}

var playGame = function(game){};

playGame.prototype = {
     preload: function(){
           game.load.image("tile", "tile.png");
     },
     create: function(){
          for(var i = 0; i < gridHeight; i++){
               maze[i] = [];
               for(var j = 0; j < gridWidth; j++){
                    maze[i][j] = 0;
                    if(game.rnd.between(0, wallRatio) == 0){
                         maze[i][j] = 1;
                         var wall = game.add.sprite(i * tileSize, j * tileSize, "tile");   
                         wall.tint = 0xff0000;       
                    }
               }
          }
          var startCol = game.rnd.between(0, gridWidth - 1);
          var startRow = game.rnd.between(0, gridHeight - 1);
          this.lineGroup = game.add.group();
          this.playerPosition = game.add.sprite(startCol * tileSize, startRow * tileSize, "tile");
          this.playerPosition.tint = 0x00ff00;
          this.playerPosition.alpha = 0.5;
          this.playerPosition.inputEnabled = true;
          this.playerPosition.input.enableDrag();
          this.playerPosition.input.boundsRect = new Phaser.Rectangle(0, 0, game.width, game.height);
          this.playerPosition.input.enableSnap(tileSize, tileSize, true, true);
          
     },
     update: function(){
          this.lineGroup.removeAll(true);
          this.drawCircle(this.playerPosition.x / tileSize, this.playerPosition.y / tileSize, sightRadius);
     },
     drawBresenham: function(x0, y0, x1, y1){
          var dx = Math.abs(x1 - x0);
          var sx = -1;
          if(x0 < x1){
               var sx = 1
          }
          var dy = Math.abs(y1 - y0);
          var sy = -1;
          if(y0 < y1){
               var sy = 1;
          }
          var err = -dy / 2;
          if(dx > dy){
               err = dx / 2;
          }
          do{
               if(x0 < 0 || y0 < 0 || x0 >= gridWidth || y0 >= gridHeight || maze[x0][y0] == 1){
                    break;
               }
               var tile = game.add.sprite(x0 * tileSize, y0 * tileSize, "tile");
               this.lineGroup.add(tile);
               var e2 = err;
               if(e2 > -dx){
                    err -= dy;
                    x0 += sx;
               }
               if(e2 < dy){
                    err += dx;
                    y0 += sy;
               }
          } while(x0 != x1 || y0 != y1)        
     },
     drawCircle: function(x0, y0, radius){
          var x = -radius
          var y = 0;
          var err = 2 - 2 * radius; 
          do {
               this.drawBresenham(this.playerPosition.x / tileSize, this.playerPosition.y / tileSize, (x0 - x), (y0 + y));
               this.drawBresenham(this.playerPosition.x / tileSize, this.playerPosition.y / tileSize, (x0 - y), (y0 - x));
               this.drawBresenham(this.playerPosition.x / tileSize, this.playerPosition.y / tileSize, (x0 + x), (y0 - y));
               this.drawBresenham(this.playerPosition.x / tileSize, this.playerPosition.y / tileSize, (x0 + y), (y0 + x));
               radius = err;
               if (radius <= y){
                    y++;
                    err += y * 2 + 1;
               }          
               if (radius > x || err > y){
                    x++;
                    err += x * 2 + 1;
               } 
          } while (x < 0);    
     }
}