public boolean checkhit(Coord c) {
	c = c.add(ul().inv());
	if((c.x < 0) || (c.y < 0) || (c.x >= img.sz.x) || (c.y >= img.sz.y))
	    return(false);
	int cl = img.img.getRGB(c.x, c.y);
	return(Utils.rgbm.getAlpha(cl) >= 128);
    }