constructor(x_,y_,type_,borderT_,borderR_,borderB_,borderL_) {

    this.x = x_;

    this.y = y_;

    this.size = tileSize;

    this.type = type_; // start, goal, arenaA, arenaB

    this.borderT = borderT_;

    this.borderR = borderR_;

    this.borderB = borderB_;

    this.borderL = borderL_;

    // make objects out of borders

    if(this.borderT) {

      rubicons.push(new LineSeg(createVector(this.x,this.y),createVector(this.x + this.size,this.y)));

    }

    if(this.borderR) {

      rubicons.push(new LineSeg(createVector(this.x + this.size,this.y),createVector(this.x + this.size,this.y + this.size)));

    }

    if(this.borderB) {

      rubicons.push(new LineSeg(createVector(this.x,this.y + this.size),createVector(this.x + this.size,this.y + this.size)));

    }

    if(this.borderL) {

      rubicons.push(new LineSeg(createVector(this.x,this.y),createVector(this.x,this.y + this.size)));

    }

  } // constructor

  show() {

    fill(0,0,255,50);

    noStroke();

    rect(this.x,this.y,this.size,this.size);

    stroke(0);

    strokeCap(SQUARE);

    strokeWeight(4);

    if(this.borderT) {

      line(this.x,this.y,this.x + this.size,this.y);

    }

    if(this.borderR) {

      line(this.x + this.size,this.y,this.x + this.size,this.y + this.size);

    }

    if(this.borderB) {

      line(this.x,this.y + this.size,this.x + this.size,this.y + this.size);

    }

    if(this.borderL) {

      line(this.x,this.y,this.x,this.y + this.size);

    }

  }

} // Tile