drawDebugPoint(x, y, debugText = '', color = '#f00') {
    let point = document.createElementNS('http://www.w3.org/2000/svg', 'circle');
    point.setAttributeNS(null, 'cx', x);
    point.setAttributeNS(null, 'cy', y);
    point.setAttributeNS(null, 'r', '2');
    point.setAttributeNS(null, 'fill', '#f00');
    this.vertices.push(point);
    this.drawDebugText(x, y, debugText);
  }
Draws a debug dot at a given coordinate and adds text.

@param {Number} x The x coordinate.
@param {Number} y The y coordindate.
@param {String} [debugText=''] A string.
@param {String} [color='#f00'] A color in hex form.