/*  call-seq:
 *    draw_line(point1, point2, color)
 *
 *  Draw a line segment between two points on the Surface.
 *  See also #draw_line_a
 *
 *  This method takes these arguments:
 *  point1::  the coordinates of one end of the line, [x1,y1].
 *  point2::  the coordinates of the other end of the line, [x2,y2].
 *  color::   the color of the shape, [r,g,b,a]. If alpha
 *            is omitted, it is drawn at full opacity.
 */
VALUE rbgm_draw_line(VALUE target, VALUE pt1, VALUE pt2, VALUE rgba)
{
  draw_line(target,pt1,pt2,rgba,0); /* no anti-aliasing */
  return target;
}