0)";
      ctx.beginPath();
      for(var i=0,n=w.walls.length;i<n;i++) {
        var q = w.walls[i];
        ctx.moveTo(q.p1.x, q.p1.y);
        ctx.lineTo(q.p2.x, q.p2.y);
      }
      ctx.stroke();

      // draw agents
      // color agent based on reward it is experiencing at the moment
      var r = 0;
      ctx.fillStyle = "rgb(" + r + ", 150, 150)";
      ctx.strokeStyle = "rgb(0,0,0)";
      for(var i=0,n=agents.length;i<n;i++) {
        var a = agents[i];
        
        // draw agents body
    