sclass LineWithColor implements RenderableWithHints {
  Pt a, b;
  RGB color;
  int width = 14;
  
  *() {}
  *(Pt *a, Pt *b, RGB *color) {}

  public void renderOn(Graphics2D g, int w, int h) {
    drawRoundEdgeLine(g, a, b, toColor(color), width);
  }
  
  public void renderHints(Graphics2D g, int w, int h) {
    fillRect(g, a.x, a.y, 1, 1, hintColor());
    fillRect(g, b.x, b.y, 1, 1, hintColor());
  }
  
  // 0 to 360 (clockwise, 0 is north)
  double angle() {
    double angle = Math.toDegrees(Math.atan2(b.y-a.y, b.x-a.x));
    ret angle < 0 ? angle + 360 : angle;
  }
}