snake.js

function Snake(){
	this.x = 0;
	this.y = 0;
	this.xspeed = 100;
	this.yspeed = 100;
	this.total = 0;
	this.tail = [];

	this.eat = function(food){
		var d = dist(this.x, this.y, 20*food.x, 20*food.y);
		if(d < 1){
			this.total ++;
			return true;
		}
		else 
			return false;
	}

    this.dir = function(x, y){
        this.xspeed = x;
        this.yspeed = y;
	}
	
	this.update = function(){
		if(this.total === this.tail.length){
			for(var 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(){
		fill(255);
		for(var i = 0; i < this.tail.length; i++){
			rect(this.tail[i].x, this.tail[i].y, scl, scl);
		}
		fill(255);
		rect(this.x, this.y, scl, scl);
		
	}
}