snake.js

var s;
var scl=20;
var food;
function setup() {
 createCanvas(600,600);
 frameRate(10);
 s=new Snake();
 pickLocation();
}

function keyPressed(){
 if(keyCode===UP_ARROW){
  s.dir(0,-1); 
 } else if(keyCode===DOWN_ARROW){
  s.dir(0,1); 
 } else if(keyCode===LEFT_ARROW){
  s.dir(-1,0); 
 } else if(keyCode===RIGHT_ARROW){
  s.dir(1,0); 
 } 
}

function pickLocation(){
  cols=floor(width/scl);
  rows=floor(height/scl);
  food=createVector(floor(random(cols)),floor(random(rows)));
  food.mult(scl);
}


function draw() {
 background(51);
 s.death();
 s.update();
 s.show();
 if (s.eat(food)){
   s.total++;
   pickLocation();
 }
 fill(255,0,100);
 rect(food.x,food.y,scl,scl);
}

function Snake(){
  this.x=0;
  this.y=0;
  this.xspeed=1;
  this.yspeed=0;
  this.total=0;
  this.tail=[];
  this.dir =function(x,y){
   this.xspeed=x;
   this.yspeed=y;
  }
  this.death= function(){
    for(i=0;i<this.tail.length;i++){
      var pos=this.tail[i];
      var d=dist(pos.x,pos.y,this.x,this.y);
      if (d<5){
       this.total=0;
       this.tail=[];
      }
    }
  }
  
  this.update = function(){
    if(this.total===this.tail.length){
    
    for(i=0;i<this.tail.length-1;i++){
      this.tail[i]=this.tail[i+1];
    }
    }
    this.tail[this.total-1]=createVector(this.x,this.y);
    
    this.x=this.x+this.xspeed*scl;
    this.y=this.y+this.yspeed*scl;
    this.x=constrain(this.x,0,width-scl);
    this.y=constrain(this.y,0,height-scl);
  }
  
  this.show = function(){
    for(i=0;i<this.total;i++){
      fill(255);
      rect(this.tail[i].x,this.tail[i].y,scl,scl);
    }
    fill(255);
    rect(this.x,this.y,scl,scl);
  }
  this.eat = function(pos){
    var d=dist(this.x,this.y,pos.x,pos.y);
    if (d<5){
     return true; 
    } else{
    return false;
    }
    
  }
}