/*  call-seq:
 *    draw_line_a(point1, point2, color)
 *
 *  Like #draw_line, but the line will be anti-aliased.
 */
VALUE rbgm_draw_aaline(VALUE target, VALUE pt1, VALUE pt2, VALUE rgba)
{
  draw_line(target,pt1,pt2,rgba,1); /* anti-aliasing */
  return target;
}