class TrailPolygon extends TrailShape {

  int nSides;
  
  TrailPolygon(float x, float y, float dx, float dy,
  float size, float dSizePercent, color sColor, int nSides) {
    super(x, y, dx, dy, size, dSizePercent, sColor);
    this.nSides = nSides;
  }

  /**
   * Draws an equilateral polygon with sides of the
   * given size, centered at (x,y).
   *
   * It works by figuring out the length of a line from
   * the center of the polygon to the outer edge (called
   * interiorLength). A line from (0,0) to (interiorlength, 0)
   * is rotated in steps of 360/nSides to determine the
   * vertices of the polygon.
   *
   */
  void drawShape(float x, float y, float size)
  {
    float interiorLength = size / 2 * cos(radians(90.0 * (nSides - 2) / nSides));
    float dTheta = 360.0 / nSides;
    float vx = interiorLength;
    float vy = 0;
    beginShape();
    for (int i = 0; i <= nSides; i++)
    {
        vertex(x + vx, y + vy);
        vx = interiorLength * cos(radians(i * dTheta));
        vy = interiorLength * sin(radians(i * dTheta));
    }
    endShape(CLOSE);
  }
}