/* 
 *  call-seq:
 *    draw_circle(center, radius, color)
 *
 *  Draw a non-solid circle on the Surface, given the coordinates of its
 *  center and its radius. See also #draw_circle_a and #draw_circle_s
 *
 *  This method takes these arguments:
 *  center::  the coordinates of circle's center, [x,y].
 *  radius::  the radius (pixels) of the circle.
 *  color::   the color of the shape, [r,g,b,a]. If alpha
 *            is omitted, it is drawn at full opacity.
 */
VALUE rbgm_draw_circle(VALUE target, VALUE center, VALUE radius, VALUE rgba)
{
  draw_circle(target,center,radius,rgba,0,0); /* no aa, no fill */
  return target;
}