void draw_slash()
{
	np_canvas c = get_active_canvas();
	np_image img = get_active_image();
	int w = get_width(img); //キャンバスの幅を取得
	int h = get_height(img); //キャンバスの高さを取得

// 横の幅決定
	read_mouse_input(c,"input mouse pos1");
	np_point p1 = get_mouse_point(c);

	read_mouse_input(c,"input mouse pos2");
	np_point p2 = get_mouse_point(c);

	read_mouse_input(c,"input mouse pos3");
	np_point p3 = get_mouse_point(c);

	// 斜線向き判断用
	double px = p2.x - p1.x ;
	double py = p2.y - p1.y ;

	// 幅決定
		double p4x = ((p2.x - p1.x) * (p3.y - p1.y) / (p2.y - p1.y) ) + p1.x ;
		double p5y = p2.y - ((p2.y - p1.y) * (p2.x - p3.x) / (p2.x - p1.x) )  ;
		double x = p3.x - p4x ;
		double y = p3.y - p5y ;

	if ( y < 0 ) {	y = y * (-1) ; }
	if ( x < 0 ) {	x = x * (-1) ; }


if ( px < 0 && 0 < py || py < 0 && 0 < px) {

		double a = (p2.y - p1.y) * ( -30 - x / 3);
		double p6y = a / (p2.x - p1.x) ;

		double b = (p2.x - p1.x) * ( -30 - y / 3);
		double p7x = b / (p2.y - p1.y) ;


	for (int i = 0; i <= h / y + w / x ; ++i) {
		draw_line(c, p7x + (i * x), -30, -30, p6y + (i * y));
	}

}else {
		double a = (p2.y - p1.y) * ( x / 3 - ( -30 ));
		double p6y = h - (a / (p2.x - p1.x)) ;

		double b = (p2.x - p1.x) * ( ( h + 30 ) - ( h - y / 3));
		double p7x = b / (p2.y - p1.y) ;

	for (int i = 0; i <= h / y + w / x ; ++i) {
		draw_line(c , (-30)  , p6y - (i * y) , p7x + (i * x) , (h + 30) );
	}
}

}

/////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////

// 右上がり斜線

void draw_slash45a()
{
	np_canvas c = get_active_canvas();
	np_image img = get_active_image();
	int w = get_width(img); //キャンバスの幅を取得
	int h = get_height(img); //キャンバスの高さを取得

// 横の幅決定
	read_mouse_input(c,"input mouse pos1");
	np_point p1 = get_mouse_point(c);

	read_mouse_input(c,"input mouse pos2");
	np_point p2 = get_mouse_point(c);

	// 幅決定

		double x = p1.y - p2.y + p1.x - p2.x ;

	if ( x < 0 ) {	x = x * (-1) ; }

		double a = (p1.x - p1.y) * ( -30 - x / 3);
		double p3y = a / (p1.y - p1.x) ;

	for (int i = 0; i <= h / x + w / x ; ++i) {
		draw_line(c, p3y + (i * x), -30, -30, p3y + (i * x));
	}

}


/////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////

// 右下がり斜線

void draw_slash45b()
{
	np_canvas c = get_active_canvas();
	np_image img = get_active_image();
	int w = get_width(img); //キャンバスの幅を取得
	int h = get_height(img); //キャンバスの高さを取得

// 横の幅決定
	read_mouse_input(c,"input mouse pos1");
	np_point p1 = get_mouse_point(c);

	read_mouse_input(c,"input mouse pos2");
	np_point p2 = get_mouse_point(c);

	// 幅決定

		double x = p2.x - (p1.x - (p1.y - p2.y));

	if ( x < 0 ) {	x = x * (-1) ; }

		double p3y = h - ( x / 3 + 30) ;
		double p4x = x / 3 + 30 ;

	for (int i = 0; i <= h / x + w / x ; ++i) {
		draw_line(c , (-30)  , p3y - (i * x) , p4x + (i * x) , (h + 30) );
	}

}