public void render() {
      // Draw a triangle rotated in the direction of velocity
      float theta = vel.heading2D() + PApplet.radians(90);
      fill(100);
      stroke(0);
      pushMatrix();
      translate(loc.x, loc.y);
      rotate(theta);
      beginShape(PConstants.TRIANGLES);
      vertex(0, -r * 2);
      vertex(-r, r * 2);
      vertex(r, r * 2);
      endShape();

      if (debug) {
        stroke(50);
        line(0, 0, 0, -sight);
      }
      popMatrix();
    }