function Glyph() {
  /**
   * Object containing dimensions of the character as rendered to a canvas.
   * @see {writeTextToCanvas}
   * @type {object}
   * @private
   */
  this.dimensions = undefined;

  /**
   * Reference to loaded image data for a single character, drawn in a particular style, shared and referenced across all labels.
   * @type {BillboardTexture}
   * @private
   */
  this.billboardTexture = undefined;

  /**
   * The individual billboard used to render the glyph. This may be <code>undefined</code> if the associated character is whitespace.
   * @type {Billboard|undefined}
   * @private
   */
  this.billboard = undefined;
}
A glyph represents a single character in label.
@private